Initial commit

env/lib/python3.10/site-packages/wagtail/search/backends/database/__init__.py

@@ -0,0 +1,50 @@
+import warnings
+
+from django.db import connection
+
+USE_SQLITE_FTS = None  # True if sqlite FTS is available, False if not, None if untested
+
+
+def SearchBackend(params):
+    """
+    Returns the appropriate search backend for the current 'default' database system
+    """
+    if connection.vendor == "postgresql":
+        from .postgres.postgres import PostgresSearchBackend
+
+        return PostgresSearchBackend(params)
+    elif connection.vendor == "mysql":
+        from .mysql.mysql import MySQLSearchBackend
+
+        return MySQLSearchBackend(params)
+    elif connection.vendor == "sqlite":
+        global USE_SQLITE_FTS
+
+        if USE_SQLITE_FTS is None:
+            from .sqlite.utils import fts5_available, fts_table_exists
+
+            if not fts5_available():
+                USE_SQLITE_FTS = False
+            elif not fts_table_exists():
+                USE_SQLITE_FTS = False
+                warnings.warn(
+                    "The installed SQLite library supports full-text search, but the table for storing "
+                    "searchable content is missing. This probably means SQLite was upgraded after the "
+                    "migration was applied. To enable full-text search, reapply wagtailsearch migration 0006 "
+                    "or create the table manually."
+                )
+            else:
+                USE_SQLITE_FTS = True
+
+        if USE_SQLITE_FTS:
+            from .sqlite.sqlite import SQLiteSearchBackend
+
+            return SQLiteSearchBackend(params)
+        else:
+            from .fallback import DatabaseSearchBackend
+
+            return DatabaseSearchBackend(params)
+    else:
+        from .fallback import DatabaseSearchBackend
+
+        return DatabaseSearchBackend(params)

env/lib/python3.10/site-packages/wagtail/search/backends/database/fallback.py

@@ -0,0 +1,249 @@
+from collections import OrderedDict
+from warnings import warn
+
+from django.core.exceptions import FieldDoesNotExist
+from django.db import models
+from django.db.models import Count
+from django.db.models.expressions import Value
+
+from wagtail.search.backends.base import (
+    BaseSearchBackend,
+    BaseSearchQueryCompiler,
+    BaseSearchResults,
+    FilterFieldError,
+)
+from wagtail.search.query import And, Boost, MatchAll, Not, Or, Phrase, PlainText
+from wagtail.search.utils import AND, OR
+
+# This file implements a database search backend using basic substring matching, and no
+# database-specific full-text search capabilities. It will be used in the following cases:
+# * The current default database is SQLite <3.19, or SQLite built without fulltext
+#   extensions, or something other than PostgreSQL, MySQL or SQLite
+# * 'wagtail.search.backends.database.fallback' is specified directly as the search backend
+
+
+MATCH_ALL = "_ALL_"
+MATCH_NONE = "_NONE_"
+
+
+class DatabaseSearchQueryCompiler(BaseSearchQueryCompiler):
+    DEFAULT_OPERATOR = "and"
+    OPERATORS = {
+        "and": AND,
+        "or": OR,
+    }
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+        self.fields_names = list(self.get_fields_names())
+
+    def get_fields_names(self):
+        model = self.queryset.model
+        fields_names = self.fields or [
+            field.field_name for field in model.get_searchable_search_fields()
+        ]
+        # Check if the field exists (this will filter out indexed callables)
+        for field_name in fields_names:
+            try:
+                model._meta.get_field(field_name)
+            except FieldDoesNotExist:
+                continue
+            else:
+                yield field_name
+
+    def _process_lookup(self, field, lookup, value):
+        return models.Q(
+            **{field.get_attname(self.queryset.model) + "__" + lookup: value}
+        )
+
+    def _connect_filters(self, filters, connector, negated):
+        if connector == "AND":
+            q = models.Q(*filters)
+        elif connector == "OR":
+            q = OR([models.Q(fil) for fil in filters])
+        else:
+            return
+
+        if negated:
+            q = ~q
+
+        return q
+
+    def build_single_term_filter(self, term):
+        term_query = models.Q()
+        for field_name in self.fields_names:
+            term_query |= models.Q(**{field_name + "__icontains": term})
+        return term_query
+
+    def check_boost(self, query, boost=1.0):
+        if query.boost * boost != 1.0:
+            warn("Database search backend does not support term boosting.")
+
+    def build_database_filter(self, query, boost=1.0):
+        if isinstance(query, PlainText):
+            self.check_boost(query, boost=boost)
+
+            operator = self.OPERATORS[query.operator]
+
+            return operator(
+                [
+                    self.build_single_term_filter(term)
+                    for term in query.query_string.split()
+                ]
+            )
+
+        if isinstance(query, Phrase):
+            q = models.Q()
+            for field_name in self.fields_names:
+                q |= models.Q(**{field_name + "__icontains": query.query_string})
+            return q
+
+        if isinstance(query, Boost):
+            boost *= query.boost
+            return self.build_database_filter(query.subquery, boost=boost)
+
+        if isinstance(query, MatchAll):
+            return MATCH_ALL
+
+        if isinstance(query, Not):
+            q = self.build_database_filter(query.subquery, boost=boost)
+
+            if q == MATCH_ALL:
+                return MATCH_NONE
+
+            elif q == MATCH_NONE:
+                return MATCH_ALL
+
+            else:
+                return ~q
+
+        if isinstance(query, And):
+            subqueries = [
+                self.build_database_filter(subquery, boost=boost)
+                for subquery in query.subqueries
+            ]
+
+            # If there's a MATCH_NONE, return MATCH_NONE
+            if MATCH_NONE in subqueries:
+                return MATCH_NONE
+
+            # Ignore MATCH_ALL
+            subqueries = [q for q in subqueries if q != MATCH_ALL]
+
+            return AND(subqueries)
+
+        if isinstance(query, Or):
+            subqueries = [
+                self.build_database_filter(subquery, boost=boost)
+                for subquery in query.subqueries
+            ]
+
+            # If there's a MATCH_ALL, return MATCH_ALL
+            if MATCH_ALL in subqueries:
+                return MATCH_ALL
+
+            # Ignore MATCH_NONE
+            subqueries = [q for q in subqueries if q != MATCH_NONE]
+
+            return OR(subqueries)
+
+        raise NotImplementedError(
+            "`%s` is not supported by the database search backend."
+            % query.__class__.__name__
+        )
+
+
+class DatabaseAutocompleteQueryCompiler(DatabaseSearchQueryCompiler):
+    # The fallback backend doesn't handle word boundaries, so standard searches are
+    # essentially equivalent to autocomplete queries anyhow. However, to provide a
+    # consistent API with other backends, we provide both endpoints.
+    pass
+
+
+class DatabaseSearchResults(BaseSearchResults):
+    iterator_chunk_size = 2000
+
+    def get_queryset(self):
+        queryset = self.query_compiler.queryset
+
+        # Run _get_filters_from_queryset to test that no fields that are not
+        # a FilterField have been used in the query.
+        self.query_compiler._get_filters_from_queryset()
+
+        q = self.query_compiler.build_database_filter(self.query_compiler.query)
+
+        if q == MATCH_ALL:
+            pass
+        elif q == MATCH_NONE:
+            queryset = queryset.none()
+        else:
+            queryset = queryset.filter(q)
+
+        return queryset.distinct()[self.start : self.stop]
+
+    def _do_search(self):
+        queryset = self.get_queryset()
+
+        if self._score_field:
+            queryset = queryset.annotate(
+                **{self._score_field: Value(None, output_field=models.FloatField())}
+            )
+
+        return queryset.iterator(self.iterator_chunk_size)
+
+    def _do_count(self):
+        return self.get_queryset().count()
+
+    supports_facet = True
+
+    def facet(self, field_name):
+        # Get field
+        field = self.query_compiler._get_filterable_field(field_name)
+        if field is None:
+            raise FilterFieldError(
+                'Cannot facet search results with field "'
+                + field_name
+                + "\". Please add index.FilterField('"
+                + field_name
+                + "') to "
+                + self.query_compiler.queryset.model.__name__
+                + ".search_fields.",
+                field_name=field_name,
+            )
+
+        query = self.get_queryset()
+        results = (
+            query.values(field_name).annotate(count=Count("pk")).order_by("-count")
+        )
+
+        return OrderedDict(
+            [(result[field_name], result["count"]) for result in results]
+        )
+
+
+class DatabaseSearchBackend(BaseSearchBackend):
+    query_compiler_class = DatabaseSearchQueryCompiler
+    autocomplete_query_compiler_class = DatabaseSearchQueryCompiler
+    results_class = DatabaseSearchResults
+
+    def reset_index(self):
+        pass  # Not needed
+
+    def add_type(self, model):
+        pass  # Not needed
+
+    def refresh_index(self):
+        pass  # Not needed
+
+    def add(self, obj):
+        pass  # Not needed
+
+    def add_bulk(self, model, obj_list):
+        return  # Not needed
+
+    def delete(self, obj):
+        pass  # Not needed
+
+
+# This line allows using 'wagtail.search.backends.database.fallback' as the backend, bypassing the automatic selection of the backend that would get run if the user chose 'wagtail.search.backends.database'
+SearchBackend = DatabaseSearchBackend

env/lib/python3.10/site-packages/wagtail/search/backends/database/mysql/mysql.py

@@ -0,0 +1,684 @@
+import warnings
+from collections import OrderedDict
+
+from django.db import DEFAULT_DB_ALIAS, NotSupportedError, connections, transaction
+from django.db.models import Case, When
+from django.db.models.aggregates import Avg, Count
+from django.db.models.constants import LOOKUP_SEP
+from django.db.models.expressions import F
+from django.db.models.fields import BooleanField, FloatField, TextField
+from django.db.models.functions.comparison import Cast
+from django.db.models.functions.text import Length
+from django.db.models.manager import Manager
+from django.db.models.query_utils import Q
+from django.utils.encoding import force_str
+from django.utils.functional import cached_property
+
+from wagtail.search.backends.base import (
+    BaseSearchBackend,
+    BaseSearchQueryCompiler,
+    BaseSearchResults,
+    FilterFieldError,
+)
+from wagtail.search.backends.database.mysql.query import (
+    Lexeme,
+    MatchExpression,
+    SearchQuery,
+)
+from wagtail.search.index import (
+    AutocompleteField,
+    RelatedFields,
+    SearchField,
+    get_indexed_models,
+)
+from wagtail.search.models import IndexEntry
+from wagtail.search.query import And, Boost, MatchAll, Not, Or, Phrase, PlainText
+from wagtail.search.utils import (
+    OR,
+    balanced_reduce,
+    get_content_type_pk,
+    get_descendants_content_types_pks,
+)
+
+
+class ObjectIndexer:
+    """
+    Responsible for extracting data from an object to be inserted into the index.
+    """
+
+    def __init__(self, obj, backend):
+        self.obj = obj
+        self.search_fields = obj.get_search_fields()
+        self.config = backend.config
+
+    def prepare_value(self, value):
+        if isinstance(value, str):
+            return value
+
+        elif isinstance(value, list):
+            return ", ".join(self.prepare_value(item) for item in value)
+
+        elif isinstance(value, dict):
+            return ", ".join(self.prepare_value(item) for item in value.values())
+
+        return force_str(value)
+
+    def prepare_field(self, obj, field):
+        if isinstance(field, SearchField):
+            yield (field, self.prepare_value(field.get_value(obj)))
+
+        elif isinstance(field, AutocompleteField):
+            yield (field, self.prepare_value(field.get_value(obj)))
+
+        elif isinstance(field, RelatedFields):
+            sub_obj = field.get_value(obj)
+            if sub_obj is None:
+                return
+
+            if isinstance(sub_obj, Manager):
+                sub_objs = sub_obj.all()
+
+            else:
+                if callable(sub_obj):
+                    sub_obj = sub_obj()
+
+                sub_objs = [sub_obj]
+
+            for sub_obj in sub_objs:
+                for sub_field in field.fields:
+                    yield from self.prepare_field(sub_obj, sub_field)
+
+    @cached_property
+    def id(self):
+        """
+        Returns the value to use as the ID of the record in the index
+        """
+        return force_str(self.obj.pk)
+
+    @cached_property
+    def title(self):
+        """
+        Returns all values to index as "title". This is the value of all SearchFields that have the field_name 'title'
+        """
+        texts = []
+        for field in self.search_fields:
+            for current_field, value in self.prepare_field(self.obj, field):
+                if (
+                    isinstance(current_field, SearchField)
+                    and current_field.field_name == "title"
+                ):
+                    texts.append(value)
+
+        return " ".join(texts)
+
+    @cached_property
+    def body(self):
+        """
+        Returns all values to index as "body". This is the value of all SearchFields excluding the title
+        """
+        texts = []
+        for field in self.search_fields:
+            for current_field, value in self.prepare_field(self.obj, field):
+                if (
+                    isinstance(current_field, SearchField)
+                    and not current_field.field_name == "title"
+                ):
+                    texts.append(value)
+
+        return " ".join(texts)
+
+    @cached_property
+    def autocomplete(self):
+        """
+        Returns all values to index as "autocomplete". This is the value of all AutocompleteFields
+        """
+        texts = []
+        for field in self.search_fields:
+            for current_field, value in self.prepare_field(self.obj, field):
+                if isinstance(current_field, AutocompleteField):
+                    texts.append(value)
+
+        return " ".join(texts)
+
+    def as_vector(self, texts, for_autocomplete=False):
+        """
+        Converts an array of strings into a SearchVector that can be indexed.
+        """
+        texts = [(text.strip(), weight) for text, weight in texts]
+        texts = [(text, weight) for text, weight in texts if text]
+
+        return " ".join(texts)
+
+
+class Index:
+    def __init__(self, backend, db_alias=None):
+        self.backend = backend
+        self.name = self.backend.index_name
+        self.db_alias = DEFAULT_DB_ALIAS if db_alias is None else db_alias
+        self.connection = connections[self.db_alias]
+        if self.connection.vendor != "mysql":
+            raise NotSupportedError(
+                "You must select a MySQL database " "to use MySQL search."
+            )
+
+        self.entries = IndexEntry._default_manager.using(self.db_alias)
+
+    def add_model(self, model):
+        pass
+
+    def refresh(self):
+        pass
+
+    def _refresh_title_norms(self, full=False):
+        """
+        Refreshes the value of the title_norm field.
+
+        This needs to be set to 'lavg/ld' where:
+         - lavg is the average length of titles in all documents (also in terms)
+         - ld is the length of the title field in this document (in terms)
+        """
+
+        lavg = (
+            self.entries.annotate(title_length=Length("title"))
+            .filter(title_length__gt=0)
+            .aggregate(Avg("title_length"))["title_length__avg"]
+        )
+
+        if full:
+            # Update the whole table
+            # This is the most accurate option but requires a full table rewrite
+            # so we can't do it too often as it could lead to locking issues.
+            entries = self.entries
+
+        else:
+            # Only update entries where title_norm is 1.0
+            # This is the default value set on new entries.
+            # It's possible that other entries could have this exact value but there shouldn't be too many of those
+            entries = self.entries.filter(title_norm=1.0)
+
+        entries.annotate(title_length=Length("title")).filter(
+            title_length__gt=0
+        ).update(title_norm=lavg / F("title_length"))
+
+    def delete_stale_model_entries(self, model):
+        existing_pks = (
+            model._default_manager.using(self.db_alias)
+            .annotate(object_id=Cast("pk", TextField()))
+            .values("object_id")
+        )
+        content_types_pks = get_descendants_content_types_pks(model)
+        stale_entries = self.entries.filter(
+            content_type_id__in=content_types_pks
+        ).exclude(object_id__in=existing_pks)
+        stale_entries.delete()
+
+    def delete_stale_entries(self):
+        for model in get_indexed_models():
+            # We don’t need to delete stale entries for non-root models,
+            # since we already delete them by deleting roots.
+            if not model._meta.parents:
+                self.delete_stale_model_entries(model)
+
+    def add_item(self, obj):
+        self.add_items(obj._meta.model, [obj])
+
+    def add_items_update_then_create(self, content_type_pk, indexers):
+        ids_and_data = {}
+        for indexer in indexers:
+            ids_and_data[indexer.id] = (
+                indexer.title,
+                indexer.autocomplete,
+                indexer.body,
+            )
+
+        index_entries_for_ct = self.entries.filter(content_type_id=content_type_pk)
+        indexed_ids = frozenset(
+            index_entries_for_ct.filter(object_id__in=ids_and_data.keys()).values_list(
+                "object_id", flat=True
+            )
+        )
+        for indexed_id in indexed_ids:
+            title, autocomplete, body = ids_and_data[indexed_id]
+            index_entries_for_ct.filter(object_id=indexed_id).update(
+                title=title, autocomplete=autocomplete, body=body
+            )
+
+        to_be_created = []
+        for object_id in ids_and_data.keys():
+            if object_id not in indexed_ids:
+                title, autocomplete, body = ids_and_data[object_id]
+                to_be_created.append(
+                    IndexEntry(
+                        content_type_id=content_type_pk,
+                        object_id=object_id,
+                        title=title,
+                        autocomplete=autocomplete,
+                        body=body,
+                    )
+                )
+
+        self.entries.bulk_create(to_be_created)
+
+        self._refresh_title_norms()
+
+    def add_items(self, model, objs):
+        search_fields = model.get_search_fields()
+        if not search_fields:
+            return
+
+        indexers = [ObjectIndexer(obj, self.backend) for obj in objs]
+
+        # TODO: Delete unindexed objects while dealing with proxy models.
+        if indexers:
+            content_type_pk = get_content_type_pk(model)
+
+            update_method = self.add_items_update_then_create
+            update_method(content_type_pk, indexers)
+
+    def delete_item(self, item):
+        item.index_entries.all()._raw_delete(using=self.db_alias)
+
+    def __str__(self):
+        return self.name
+
+
+class MySQLSearchQueryCompiler(BaseSearchQueryCompiler):
+    DEFAULT_OPERATOR = "and"
+    LAST_TERM_IS_PREFIX = False
+    TARGET_SEARCH_FIELD_TYPE = SearchField
+    FTS_TABLE_FIELDS = ["title", "body"]
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        local_search_fields = self.get_search_fields_for_model()
+
+        if self.fields is None:
+            # search over the fields defined on the current model
+            self.search_fields = local_search_fields
+        else:
+            # build a search_fields set from the passed definition,
+            # which may involve traversing relations
+            self.search_fields = {
+                field_lookup: self.get_search_field(
+                    field_lookup, fields=local_search_fields
+                )
+                for field_lookup in self.fields
+            }
+
+    def get_config(self, backend):
+        return backend.config
+
+    def get_search_fields_for_model(self):
+        return self.queryset.model.get_searchable_search_fields()
+
+    def get_search_field(self, field_lookup, fields=None):
+        if fields is None:
+            fields = self.search_fields
+
+        if LOOKUP_SEP in field_lookup:
+            field_lookup, sub_field_name = field_lookup.split(LOOKUP_SEP, 1)
+        else:
+            sub_field_name = None
+
+        for field in fields:
+            if (
+                isinstance(field, self.TARGET_SEARCH_FIELD_TYPE)
+                and field.field_name == field_lookup
+            ):
+                return field
+
+            # Note: Searching on a specific related field using
+            # `.search(fields=…)` is not yet supported by Wagtail.
+            # This method anticipates by already implementing it.
+            if isinstance(field, RelatedFields) and field.field_name == field_lookup:
+                return self.get_search_field(sub_field_name, field.fields)
+
+    def build_search_query_content(self, query, invert=False):
+        if isinstance(query, PlainText):
+            terms = query.query_string.split()
+            if not terms:
+                return None
+
+            last_term = terms.pop()
+
+            lexemes = Lexeme(last_term, invert=invert, prefix=self.LAST_TERM_IS_PREFIX)
+            for term in terms:
+                new_lexeme = Lexeme(term, invert=invert)
+
+                if query.operator == "and":
+                    lexemes &= new_lexeme
+                else:
+                    lexemes |= new_lexeme
+
+            return SearchQuery(lexemes)
+
+        elif isinstance(query, Phrase):
+            return SearchQuery(query.query_string, search_type="phrase")
+
+        elif isinstance(query, Boost):
+            # Not supported
+            msg = "The Boost query is not supported by the MySQL search backend."
+            warnings.warn(msg, RuntimeWarning)
+
+            return self.build_search_query_content(query.subquery, invert=invert)
+
+        elif isinstance(query, Not):
+            return self.build_search_query_content(query.subquery, invert=not invert)
+
+        elif isinstance(query, (And, Or)):
+            # If this part of the query is inverted, we swap the operator and
+            # pass down the inversion state to the child queries.
+            # This works thanks to De Morgan's law.
+            #
+            # For example, the following query:
+            #
+            #   Not(And(Term("A"), Term("B")))
+            #
+            # Is equivalent to:
+            #
+            #   Or(Not(Term("A")), Not(Term("B")))
+            #
+            # It's simpler to code it this way as we only need to store the
+            # invert status of the terms rather than all the operators.
+
+            subquery_lexemes = [
+                self.build_search_query_content(subquery, invert=invert)
+                for subquery in query.subqueries
+            ]
+
+            is_and = isinstance(query, And)
+
+            if invert:
+                is_and = not is_and
+
+            if is_and:
+                return balanced_reduce(lambda a, b: a & b, subquery_lexemes)
+            else:
+                return balanced_reduce(lambda a, b: a | b, subquery_lexemes)
+
+        raise NotImplementedError(
+            "`%s` is not supported by the MySQL search backend."
+            % query.__class__.__name__
+        )
+
+    def build_search_query(self, query):
+        return self.build_search_query_content(query)
+
+    def get_index_vectors(self, search_query):
+        return [
+            (F("index_entries__title"), F("index_entries__title_norm")),
+            (F("index_entries__body"), 1.0),
+        ]
+
+    def get_fields_vectors(self, search_query):
+        raise NotImplementedError()
+
+    def get_search_vectors(self, search_query):
+        if self.fields is None:
+            return self.get_index_vectors(search_query)
+
+        else:
+            return self.get_fields_vectors(search_query)
+
+    def _build_rank_expression(self, vectors, config):
+        rank_expressions = [
+            self.build_tsrank(vector, self.query, config=config) * boost
+            for vector, boost in vectors
+        ]
+
+        rank_expression = rank_expressions[0]
+        for other_rank_expression in rank_expressions[1:]:
+            rank_expression += other_rank_expression
+
+        return rank_expression
+
+    def search(self, config, start, stop, score_field=None):
+        # TODO: Handle MatchAll nested inside other search query classes.
+        if isinstance(self.query, MatchAll):
+            return self.queryset[start:stop]
+
+        elif isinstance(self.query, Not) and isinstance(self.query.subquery, MatchAll):
+            return self.queryset.none()
+
+        if isinstance(
+            self.query, Not
+        ):  # If the outermost operator is a Not, we invert the query. This is done because, if every search term is negated, the Not() will return no results, an we want to match all results instead.
+            query = self.query.subquery
+            negated = True
+        else:
+            query = self.query
+            negated = False
+
+        search_query = self.build_search_query(query)
+        match_expression = MatchExpression(
+            search_query, columns=self.FTS_TABLE_FIELDS, output_field=BooleanField()
+        )  # For example: MATCH (`title`, `body`) AGAINST ('+query' IN BOOLEAN MODE)
+
+        # In Django 4.0 the above match expression would produce this SQL WHERE clause:
+        #
+        # WHERE ... MATCH (`title`, `body`) AGAINST (query IN BOOLEAN MODE)
+        #
+        # In Django 4.1, this behavior was changed:
+        #
+        # https://code.djangoproject.com/ticket/32691
+        # https://github.com/django/django/commit/407fe95cb116599adeb4b9ed01df5673aa5cb1db
+        #
+        # so that instead this SQL WHERE clause is generated, explicitly filtering
+        # against "= True":
+        #
+        # WHERE ... MATCH (`title`, `body`) AGAINST (query IN BOOLEAN MODE) = True
+        #
+        # This no longer works properly because MATCH returns a floating point score
+        # as a measurement of the match quality, not a boolean value:
+        #
+        # https://dev.mysql.com/doc/refman/8.0/en/fulltext-boolean.html
+        #
+        # In order for filtering on "= True" to work, we change the match expression
+        # SQL to be:
+        #
+        # WHERE ... CASE WHEN MATCH (`title`, `body`) AGAINST (query IN BOOLEAN MODE) THEN True ELSE False END = True
+        match_expression = Case(When(match_expression, then=True), default=False)
+
+        score_expression = MatchExpression(
+            search_query, columns=["title"], output_field=FloatField()
+        ) * F("title_norm") + MatchExpression(
+            search_query, columns=["body"], output_field=FloatField()
+        )
+
+        index_entries = IndexEntry.objects.annotate(score=score_expression).filter(
+            content_type_id__in=get_descendants_content_types_pks(self.queryset.model)
+        )
+        if not negated:
+            index_entries = index_entries.filter(match_expression)
+            if self.order_by_relevance:  # Only applies to the case where the outermost query is not a Not(), because if it is, the relevance score is always 0 (anything that matches is excluded from the results).
+                index_entries = index_entries.order_by(score_expression.desc())
+        else:
+            index_entries = index_entries.exclude(match_expression)
+
+        index_entries = index_entries[start:stop]  # Trim the results
+
+        object_ids = {
+            index_entry.object_id for index_entry in index_entries
+        }  # Get the set of IDs from the indexed objects, removes duplicates too
+
+        results = self.queryset.filter(id__in=object_ids)
+
+        return results
+
+    def _process_lookup(self, field, lookup, value):
+        lhs = field.get_attname(self.queryset.model) + "__" + lookup
+        return Q(**{lhs: value})
+
+    def _connect_filters(self, filters, connector, negated):
+        if connector == "AND":
+            q = Q(*filters)
+
+        elif connector == "OR":
+            q = OR([Q(fil) for fil in filters])
+
+        else:
+            return
+
+        if negated:
+            q = ~q
+
+        return q
+
+
+class MySQLAutocompleteQueryCompiler(MySQLSearchQueryCompiler):
+    LAST_TERM_IS_PREFIX = True
+    TARGET_SEARCH_FIELD_TYPE = AutocompleteField
+    FTS_TABLE_FIELDS = ["autocomplete"]
+
+    def get_config(self, backend):
+        return backend.autocomplete_config
+
+    def get_search_fields_for_model(self):
+        return self.queryset.model.get_autocomplete_search_fields()
+
+    def get_index_vectors(self, search_query):
+        return [(F("index_entries__autocomplete"), 1.0)]
+
+    def get_fields_vectors(self, search_query):
+        raise NotImplementedError()
+
+
+class MySQLSearchResults(BaseSearchResults):
+    def get_queryset(self, for_count=False):
+        if for_count:
+            start = None
+            stop = None
+        else:
+            start = self.start
+            stop = self.stop
+
+        return self.query_compiler.search(
+            self.query_compiler.get_config(self.backend),
+            start,
+            stop,
+            score_field=self._score_field,
+        )
+
+    def _do_search(self):
+        return list(self.get_queryset())
+
+    def _do_count(self):
+        return self.get_queryset(for_count=True).count()
+
+    supports_facet = True
+
+    def facet(self, field_name):
+        # Get field
+        field = self.query_compiler._get_filterable_field(field_name)
+        if field is None:
+            raise FilterFieldError(
+                'Cannot facet search results with field "'
+                + field_name
+                + "\". Please add index.FilterField('"
+                + field_name
+                + "') to "
+                + self.query_compiler.queryset.model.__name__
+                + ".search_fields.",
+                field_name=field_name,
+            )
+
+        query = self.query_compiler.search(
+            self.query_compiler.get_config(self.backend), None, None
+        )
+        results = (
+            query.values(field_name).annotate(count=Count("pk")).order_by("-count")
+        )
+
+        return OrderedDict(
+            [(result[field_name], result["count"]) for result in results]
+        )
+
+
+class MySQLSearchRebuilder:
+    def __init__(self, index):
+        self.index = index
+
+    def start(self):
+        self.index.delete_stale_entries()
+        return self.index
+
+    def finish(self):
+        self.index._refresh_title_norms(full=True)
+
+
+class MySQLSearchAtomicRebuilder(MySQLSearchRebuilder):
+    def __init__(self, index):
+        super().__init__(index)
+        self.transaction = transaction.atomic(using=index.db_alias)
+        self.transaction_opened = False
+
+    def start(self):
+        self.transaction.__enter__()
+        self.transaction_opened = True
+        return super().start()
+
+    def finish(self):
+        self.index._refresh_title_norms(full=True)
+
+        self.transaction.__exit__(None, None, None)
+        self.transaction_opened = False
+
+    def __del__(self):
+        # TODO: Implement a cleaner way to close the connection on failure.
+        if self.transaction_opened:
+            self.transaction.needs_rollback = True
+            self.finish()
+
+
+class MySQLSearchBackend(BaseSearchBackend):
+    query_compiler_class = MySQLSearchQueryCompiler
+    autocomplete_query_compiler_class = MySQLAutocompleteQueryCompiler
+
+    results_class = MySQLSearchResults
+    rebuilder_class = MySQLSearchRebuilder
+    atomic_rebuilder_class = MySQLSearchAtomicRebuilder
+
+    def __init__(self, params):
+        super().__init__(params)
+        self.index_name = params.get("INDEX", "default")
+
+        # MySQL backend currently has no config options
+        self.config = None
+        self.autocomplete_config = None
+
+        if params.get("ATOMIC_REBUILD", False):
+            self.rebuilder_class = self.atomic_rebuilder_class
+
+    def get_index_for_model(self, model, db_alias=None):
+        return Index(self, db_alias)
+
+    def get_index_for_object(self, obj):
+        return self.get_index_for_model(obj._meta.model, obj._state.db)
+
+    def reset_index(self):
+        for connection in [
+            connection
+            for connection in connections.all()
+            if connection.vendor == "mysql"
+        ]:
+            IndexEntry._default_manager.all()._raw_delete(using=connection.alias)
+
+    def add_type(self, model):
+        pass  # Not needed.
+
+    def refresh_index(self):
+        pass  # Not needed.
+
+    def add(self, obj):
+        self.get_index_for_object(obj).add_item(obj)
+
+    def add_bulk(self, model, obj_list):
+        if obj_list:
+            self.get_index_for_object(obj_list[0]).add_items(model, obj_list)
+
+    def delete(self, obj):
+        self.get_index_for_object(obj).delete_item(obj)
+
+
+SearchBackend = MySQLSearchBackend

env/lib/python3.10/site-packages/wagtail/search/backends/database/mysql/query.py

@@ -0,0 +1,254 @@
+import re
+from typing import Any, List, Tuple, Union
+
+from django.db.backends.base.base import BaseDatabaseWrapper
+from django.db.models.expressions import CombinedExpression, Expression, Value
+from django.db.models.fields import BooleanField, Field
+from django.db.models.sql.compiler import SQLCompiler
+
+
+class LexemeCombinable(Expression):
+    BITAND = "+"
+    BITOR = ""
+    invert = False  # By default, it is not inverted
+
+    def _combine(self, other, connector, reversed, node=None):
+        if not isinstance(other, LexemeCombinable):
+            raise TypeError(
+                f"Lexeme can only be combined with other Lexemes, got {type(other)}."
+            )
+        if reversed:
+            return CombinedLexeme(other, connector, self)
+        return CombinedLexeme(self, connector, other)
+
+    # On Combinable, these are not implemented to reduce confusion with Q. In
+    # this case we are actually (ab)using them to do logical combination so
+    # it's consistent with other usage in Django.
+    def bitand(self, other):
+        return self._combine(other, self.BITAND, False)
+
+    def bitor(self, other):
+        return self._combine(other, self.BITOR, False)
+
+    def __or__(self, other):
+        return self._combine(other, self.BITOR, False)
+
+    def __and__(self, other):
+        return self._combine(other, self.BITAND, False)
+
+
+class SearchQueryField(Field):
+    def db_type(self, connection):
+        return None
+
+
+class Lexeme(LexemeCombinable, Value):
+    _output_field = SearchQueryField()
+
+    def __init__(
+        self, value, output_field=None, invert=False, prefix=False, weight=None
+    ):
+        self.prefix = prefix
+        self.invert = invert
+        self.weight = weight
+        super().__init__(value, output_field=output_field)
+
+    def as_sql(self, compiler, connection):
+        param = re.sub(
+            r"\W+", " ", self.value
+        )  # Remove non-word characters. This is done to disallow the usage of full text search operators in the MATCH clause, because MySQL doesn't include these kinds of characters in FULLTEXT indexes.
+
+        template = "%s"
+
+        if self.prefix:
+            param = f"{param}*"
+        if self.invert:
+            param = f"(-{param})"
+        else:
+            param = f"{param}"
+
+        return template, [param]
+
+
+class CombinedLexeme(LexemeCombinable):
+    _output_field = SearchQueryField()
+
+    def __init__(self, lhs, connector, rhs, output_field=None):
+        super().__init__(output_field=output_field)
+        self.connector = connector
+        self.lhs = lhs
+        self.rhs = rhs
+
+    def as_sql(self, compiler, connection):
+        value_params = []
+
+        lhs_connector = self.connector
+        rhs_connector = self.connector
+
+        if (
+            self.lhs.invert and self.connector == "+"
+        ):  # NOTE: This is a special case for MySQL. If either side's operator is AND (+), and it is inverted, the operator should become NOT (-). If we did nothing, the result could would be '+X +(-Y)' for And(X, Not(Y)), which seems correct, but produces a wrong result. The solution is to turn the query into '+X -Y', which does work, and therefore this is done here.
+            # TODO: There may be a better solution than this.
+            modified_value = self.lhs.value.copy()
+            modified_value.invert = not modified_value.invert
+            lhs_connector = "-"
+            lsql, params = compiler.compile(modified_value)
+        else:
+            lsql, params = compiler.compile(self.lhs)
+        value_params.extend(params)
+
+        if self.rhs.invert and self.connector == "+":  # Same explanation as above.
+            modified_value = self.rhs.value.copy()
+            modified_value.invert = not modified_value.invert
+            rhs_connector = "-"
+            rsql, params = compiler.compile(modified_value)
+        else:
+            rsql, params = compiler.compile(self.rhs)
+        value_params.extend(params)
+
+        combined_sql = "({}{} {}{})".format(
+            lhs_connector, lsql, rhs_connector, rsql
+        )  # if self.connector is '+' (AND), then both terms will be ANDed together. We need to repeat the connector to make that work.
+        combined_value = combined_sql % tuple(value_params)
+        return "%s", [combined_value]
+
+
+class SearchQueryCombinable:
+    BITAND = "+"
+    BITOR = ""
+
+    def _combine(self, other, connector: str, reversed: bool = False):
+        if not isinstance(other, SearchQueryCombinable):
+            raise TypeError(
+                "SearchQuery can only be combined with other SearchQuery "
+                "instances, got %s." % type(other).__name__
+            )
+        if reversed:
+            return CombinedSearchQuery(other, connector, self)
+        return CombinedSearchQuery(self, connector, other)
+
+    # On Combinable, these are not implemented to reduce confusion with Q. In
+    # this case we are actually (ab)using them to do logical combination so
+    # it's consistent with other usage in Django.
+    def __or__(self, other):
+        return self._combine(other, self.BITOR, False)
+
+    def __ror__(self, other):
+        return self._combine(other, self.BITOR, True)
+
+    def __and__(self, other):
+        return self._combine(other, self.BITAND, False)
+
+    def __rand__(self, other):
+        return self._combine(other, self.BITAND, True)
+
+
+class SearchQuery(SearchQueryCombinable, Expression):
+    def __init__(
+        self, value: Union[LexemeCombinable, str], search_type: str = "lexeme", **extra
+    ):
+        super().__init__(output_field=SearchQueryField())
+        self.extra = extra
+        if (
+            isinstance(value, str) or search_type == "phrase"
+        ):  # If the value is a string, we assume it's a phrase
+            safe_string = re.sub(
+                r"\W+", " ", value
+            )  # Remove non-word characters. This is done to disallow the usage of full text search operators in the MATCH clause, because MySQL doesn't include these kinds of characters in FULLTEXT indexes.
+            self.value = Value(
+                '"%s"' % safe_string
+            )  # We wrap it in quotes to make sure it's parsed as a phrase
+        else:  # Otherwise, we assume it's a lexeme
+            self.value = value
+
+    def as_sql(
+        self,
+        compiler: SQLCompiler,
+        connection: BaseDatabaseWrapper,
+        **extra_context: Any,
+    ) -> Tuple[str, List[Any]]:
+        sql, params = compiler.compile(self.value)
+        return (sql, params)
+
+    def __repr__(self) -> str:
+        return self.value.__repr__()
+
+
+class CombinedSearchQuery(SearchQueryCombinable, CombinedExpression):
+    def __init__(self, lhs, connector, rhs, output_field=None):
+        super().__init__(lhs, connector, rhs, output_field)
+
+    def __str__(self):
+        return "%s" % super().__str__()
+
+    def as_sql(self, compiler, connection):
+        value_params = []
+
+        lhs_connector = self.connector
+        rhs_connector = self.connector
+
+        if (
+            isinstance(self.lhs, SearchQuery)
+            and isinstance(self.lhs.value, Lexeme)
+            and self.lhs.value.invert
+            and self.connector == "+"
+        ):  # NOTE: The explanation for this special case is the same as above, in the CombinedLexeme class.
+            modified_value = self.lhs.value.copy()
+            modified_value.invert = not modified_value.invert
+            lhs_connector = "-"
+            lsql, params = compiler.compile(modified_value)
+        else:
+            lsql, params = compiler.compile(self.lhs)
+        value_params.extend(params)
+
+        if (
+            isinstance(self.rhs, SearchQuery)
+            and isinstance(self.rhs.value, Lexeme)
+            and self.rhs.value.invert
+            and self.connector == "+"
+        ):  # NOTE: The explanation for this special case is the same as above, in the CombinedLexeme class.
+            modified_value = self.rhs.value.copy()
+            modified_value.invert = not modified_value.invert
+            rhs_connector = "-"
+            rsql, params = compiler.compile(modified_value)
+        else:
+            rsql, params = compiler.compile(self.rhs)
+        value_params.extend(params)
+
+        combined_sql = "({}{} {}{})".format(
+            lhs_connector, lsql, rhs_connector, rsql
+        )  # if self.connector is '+' (AND), then both terms will be ANDed together. We need to repeat the connector to make that work.
+        combined_value = combined_sql % tuple(value_params)
+        return "%s", [combined_value]
+
+
+class MatchExpression(Expression):
+    filterable = True
+    template = "MATCH (%s) AGAINST (%s IN BOOLEAN MODE)"
+
+    def __init__(
+        self,
+        query: SearchQueryCombinable,
+        columns: List[str] = None,
+        output_field: Field = BooleanField(),
+    ) -> None:
+        super().__init__(output_field=output_field)
+        self.query = query
+        self.columns = (
+            columns
+            or [
+                "title",
+                "body",
+            ]
+        )  # We need to provide a default list of columns if the user doesn't specify one. We have a joint index for for 'title' and 'body' (see wagtail.search.migrations.0006_customise_indexentry), so we'll pick that one.
+
+    def as_sql(self, compiler, connection):
+        compiled_query = compiler.compile(self.query)  # Compile the query to a string
+        formatted_query = compiled_query[0] % tuple(
+            compiled_query[1]
+        )  # Substitute the params in the query
+        column_list = ", ".join(
+            [f"`{column}`" for column in self.columns]
+        )  # ['title', 'body'] becomes '`title`, `body`'
+        params = [formatted_query]
+        return (self.template % (column_list, "%s"), params)

env/lib/python3.10/site-packages/wagtail/search/backends/database/postgres/postgres.py

@@ -0,0 +1,784 @@
+import warnings
+from collections import OrderedDict
+from functools import reduce
+
+from django.contrib.postgres.search import SearchQuery, SearchRank, SearchVector
+from django.db import DEFAULT_DB_ALIAS, NotSupportedError, connections, transaction
+from django.db.models import Avg, Count, F, Manager, Q, TextField, Value
+from django.db.models.constants import LOOKUP_SEP
+from django.db.models.functions import Cast, Length
+from django.db.models.sql.subqueries import InsertQuery
+from django.utils.encoding import force_str
+from django.utils.functional import cached_property
+
+from ....index import AutocompleteField, RelatedFields, SearchField, get_indexed_models
+from ....models import IndexEntry
+from ....query import And, Boost, MatchAll, Not, Or, Phrase, PlainText
+from ....utils import (
+    ADD,
+    MUL,
+    OR,
+    get_content_type_pk,
+    get_descendants_content_types_pks,
+)
+from ...base import (
+    BaseSearchBackend,
+    BaseSearchQueryCompiler,
+    BaseSearchResults,
+    FilterFieldError,
+)
+from .query import Lexeme
+from .weights import get_sql_weights, get_weight
+
+EMPTY_VECTOR = SearchVector(Value("", output_field=TextField()))
+
+
+class ObjectIndexer:
+    """
+    Responsible for extracting data from an object to be inserted into the index.
+    """
+
+    def __init__(self, obj, backend):
+        self.obj = obj
+        self.search_fields = obj.get_search_fields()
+        self.config = backend.config
+        self.autocomplete_config = backend.autocomplete_config
+
+    def prepare_value(self, value):
+        if isinstance(value, str):
+            return value
+
+        elif isinstance(value, list):
+            return ", ".join(self.prepare_value(item) for item in value)
+
+        elif isinstance(value, dict):
+            return ", ".join(self.prepare_value(item) for item in value.values())
+
+        return force_str(value)
+
+    def prepare_field(self, obj, field):
+        if isinstance(field, SearchField):
+            yield (
+                field,
+                get_weight(field.boost),
+                self.prepare_value(field.get_value(obj)),
+            )
+
+        elif isinstance(field, AutocompleteField):
+            # AutocompleteField does not define a boost parameter, so use a base weight of 'D'
+            yield (field, "D", self.prepare_value(field.get_value(obj)))
+
+        elif isinstance(field, RelatedFields):
+            sub_obj = field.get_value(obj)
+            if sub_obj is None:
+                return
+
+            if isinstance(sub_obj, Manager):
+                sub_objs = sub_obj.all()
+
+            else:
+                if callable(sub_obj):
+                    sub_obj = sub_obj()
+
+                sub_objs = [sub_obj]
+
+            for sub_obj in sub_objs:
+                for sub_field in field.fields:
+                    yield from self.prepare_field(sub_obj, sub_field)
+
+    def as_vector(self, texts, for_autocomplete=False):
+        """
+        Converts an array of strings into a SearchVector that can be indexed.
+        """
+        texts = [(text.strip(), weight) for text, weight in texts]
+        texts = [(text, weight) for text, weight in texts if text]
+
+        if not texts:
+            return EMPTY_VECTOR
+
+        search_config = self.autocomplete_config if for_autocomplete else self.config
+
+        return ADD(
+            [
+                SearchVector(
+                    Value(text, output_field=TextField()),
+                    weight=weight,
+                    config=search_config,
+                )
+                for text, weight in texts
+            ]
+        )
+
+    @cached_property
+    def id(self):
+        """
+        Returns the value to use as the ID of the record in the index
+        """
+        return force_str(self.obj.pk)
+
+    @cached_property
+    def title(self):
+        """
+        Returns all values to index as "title". This is the value of all SearchFields that have the field_name 'title'
+        """
+        texts = []
+        for field in self.search_fields:
+            for current_field, boost, value in self.prepare_field(self.obj, field):
+                if (
+                    isinstance(current_field, SearchField)
+                    and current_field.field_name == "title"
+                ):
+                    texts.append((value, boost))
+
+        return self.as_vector(texts)
+
+    @cached_property
+    def body(self):
+        """
+        Returns all values to index as "body". This is the value of all SearchFields excluding the title
+        """
+        texts = []
+        for field in self.search_fields:
+            for current_field, boost, value in self.prepare_field(self.obj, field):
+                if (
+                    isinstance(current_field, SearchField)
+                    and not current_field.field_name == "title"
+                ):
+                    texts.append((value, boost))
+
+        return self.as_vector(texts)
+
+    @cached_property
+    def autocomplete(self):
+        """
+        Returns all values to index as "autocomplete". This is the value of all AutocompleteFields
+        """
+        texts = []
+        for field in self.search_fields:
+            for current_field, boost, value in self.prepare_field(self.obj, field):
+                if isinstance(current_field, AutocompleteField):
+                    texts.append((value, boost))
+
+        return self.as_vector(texts, for_autocomplete=True)
+
+
+class Index:
+    def __init__(self, backend, db_alias=None):
+        self.backend = backend
+        self.name = self.backend.index_name
+        self.db_alias = DEFAULT_DB_ALIAS if db_alias is None else db_alias
+        self.connection = connections[self.db_alias]
+        if self.connection.vendor != "postgresql":
+            raise NotSupportedError(
+                "You must select a PostgreSQL database " "to use PostgreSQL search."
+            )
+
+        # Whether to allow adding items via the faster upsert method available in Postgres >=9.5
+        self._enable_upsert = self.connection.pg_version >= 90500
+
+        self.entries = IndexEntry._default_manager.using(self.db_alias)
+
+    def add_model(self, model):
+        pass
+
+    def refresh(self):
+        pass
+
+    def _refresh_title_norms(self, full=False):
+        """
+        Refreshes the value of the title_norm field.
+
+        This needs to be set to 'lavg/ld' where:
+         - lavg is the average length of titles in all documents (also in terms)
+         - ld is the length of the title field in this document (in terms)
+        """
+
+        lavg = (
+            self.entries.annotate(title_length=Length("title"))
+            .filter(title_length__gt=0)
+            .aggregate(Avg("title_length"))["title_length__avg"]
+        )
+
+        if full:
+            # Update the whole table
+            # This is the most accurate option but requires a full table rewrite
+            # so we can't do it too often as it could lead to locking issues.
+            entries = self.entries
+
+        else:
+            # Only update entries where title_norm is 1.0
+            # This is the default value set on new entries.
+            # It's possible that other entries could have this exact value but there shouldn't be too many of those
+            entries = self.entries.filter(title_norm=1.0)
+
+        entries.annotate(title_length=Length("title")).filter(
+            title_length__gt=0
+        ).update(title_norm=lavg / F("title_length"))
+
+    def delete_stale_model_entries(self, model):
+        existing_pks = (
+            model._default_manager.using(self.db_alias)
+            .annotate(object_id=Cast("pk", TextField()))
+            .values("object_id")
+        )
+        content_types_pks = get_descendants_content_types_pks(model)
+        stale_entries = self.entries.filter(
+            content_type_id__in=content_types_pks
+        ).exclude(object_id__in=existing_pks)
+        stale_entries.delete()
+
+    def delete_stale_entries(self):
+        for model in get_indexed_models():
+            # We don’t need to delete stale entries for non-root models,
+            # since we already delete them by deleting roots.
+            if not model._meta.parents:
+                self.delete_stale_model_entries(model)
+
+    def add_item(self, obj):
+        self.add_items(obj._meta.model, [obj])
+
+    def add_items_upsert(self, content_type_pk, indexers):
+        compiler = InsertQuery(IndexEntry).get_compiler(connection=self.connection)
+        title_sql = []
+        autocomplete_sql = []
+        body_sql = []
+        data_params = []
+
+        for indexer in indexers:
+            data_params.extend((content_type_pk, indexer.id))
+
+            # Compile title value
+            value = compiler.prepare_value(
+                IndexEntry._meta.get_field("title"), indexer.title
+            )
+            sql, params = value.as_sql(compiler, self.connection)
+            title_sql.append(sql)
+            data_params.extend(params)
+
+            # Compile autocomplete value
+            value = compiler.prepare_value(
+                IndexEntry._meta.get_field("autocomplete"), indexer.autocomplete
+            )
+            sql, params = value.as_sql(compiler, self.connection)
+            autocomplete_sql.append(sql)
+            data_params.extend(params)
+
+            # Compile body value
+            value = compiler.prepare_value(
+                IndexEntry._meta.get_field("body"), indexer.body
+            )
+            sql, params = value.as_sql(compiler, self.connection)
+            body_sql.append(sql)
+            data_params.extend(params)
+
+        data_sql = ", ".join(
+            [
+                f"(%s, %s, {a}, {b}, {c}, 1.0)"
+                for a, b, c in zip(title_sql, autocomplete_sql, body_sql)
+            ]
+        )
+
+        with self.connection.cursor() as cursor:
+            cursor.execute(
+                """
+                INSERT INTO %s (content_type_id, object_id, title, autocomplete, body, title_norm)
+                (VALUES %s)
+                ON CONFLICT (content_type_id, object_id)
+                DO UPDATE SET title = EXCLUDED.title,
+                              title_norm = 1.0,
+                              autocomplete = EXCLUDED.autocomplete,
+                              body = EXCLUDED.body
+                """
+                % (IndexEntry._meta.db_table, data_sql),
+                data_params,
+            )
+
+        self._refresh_title_norms()
+
+    def add_items_update_then_create(self, content_type_pk, indexers):
+        ids_and_data = {}
+        for indexer in indexers:
+            ids_and_data[indexer.id] = (
+                indexer.title,
+                indexer.autocomplete,
+                indexer.body,
+            )
+
+        index_entries_for_ct = self.entries.filter(content_type_id=content_type_pk)
+        indexed_ids = frozenset(
+            index_entries_for_ct.filter(object_id__in=ids_and_data.keys()).values_list(
+                "object_id", flat=True
+            )
+        )
+        for indexed_id in indexed_ids:
+            title, autocomplete, body = ids_and_data[indexed_id]
+            index_entries_for_ct.filter(object_id=indexed_id).update(
+                title=title, autocomplete=autocomplete, body=body
+            )
+
+        to_be_created = []
+        for object_id in ids_and_data.keys():
+            if object_id not in indexed_ids:
+                title, autocomplete, body = ids_and_data[object_id]
+                to_be_created.append(
+                    IndexEntry(
+                        content_type_id=content_type_pk,
+                        object_id=object_id,
+                        title=title,
+                        autocomplete=autocomplete,
+                        body=body,
+                    )
+                )
+
+        self.entries.bulk_create(to_be_created)
+
+        self._refresh_title_norms()
+
+    def add_items(self, model, objs):
+        search_fields = model.get_search_fields()
+        if not search_fields:
+            return
+
+        indexers = [ObjectIndexer(obj, self.backend) for obj in objs]
+
+        # TODO: Delete unindexed objects while dealing with proxy models.
+        if indexers:
+            content_type_pk = get_content_type_pk(model)
+
+            update_method = (
+                self.add_items_upsert
+                if self._enable_upsert
+                else self.add_items_update_then_create
+            )
+            update_method(content_type_pk, indexers)
+
+    def delete_item(self, item):
+        item.index_entries.all()._raw_delete(using=self.db_alias)
+
+    def __str__(self):
+        return self.name
+
+
+class PostgresSearchQueryCompiler(BaseSearchQueryCompiler):
+    DEFAULT_OPERATOR = "and"
+    LAST_TERM_IS_PREFIX = False
+    TARGET_SEARCH_FIELD_TYPE = SearchField
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        local_search_fields = self.get_search_fields_for_model()
+
+        # Due to a Django bug, arrays are not automatically converted
+        # when we use WEIGHTS_VALUES.
+        self.sql_weights = get_sql_weights()
+
+        if self.fields is None:
+            # search over the fields defined on the current model
+            self.search_fields = local_search_fields
+        else:
+            # build a search_fields set from the passed definition,
+            # which may involve traversing relations
+            self.search_fields = {
+                field_lookup: self.get_search_field(
+                    field_lookup, fields=local_search_fields
+                )
+                for field_lookup in self.fields
+            }
+
+    def get_config(self, backend):
+        return backend.config
+
+    def get_search_fields_for_model(self):
+        return self.queryset.model.get_searchable_search_fields()
+
+    def get_search_field(self, field_lookup, fields=None):
+        if fields is None:
+            fields = self.search_fields
+
+        if LOOKUP_SEP in field_lookup:
+            field_lookup, sub_field_name = field_lookup.split(LOOKUP_SEP, 1)
+        else:
+            sub_field_name = None
+
+        for field in fields:
+            if (
+                isinstance(field, self.TARGET_SEARCH_FIELD_TYPE)
+                and field.field_name == field_lookup
+            ):
+                return field
+
+            # Note: Searching on a specific related field using
+            # `.search(fields=…)` is not yet supported by Wagtail.
+            # This method anticipates by already implementing it.
+            if isinstance(field, RelatedFields) and field.field_name == field_lookup:
+                return self.get_search_field(sub_field_name, field.fields)
+
+    def build_tsquery_content(self, query, config=None, invert=False):
+        if isinstance(query, PlainText):
+            terms = query.query_string.split()
+            if not terms:
+                return None
+
+            last_term = terms.pop()
+
+            lexemes = Lexeme(last_term, invert=invert, prefix=self.LAST_TERM_IS_PREFIX)
+            for term in terms:
+                new_lexeme = Lexeme(term, invert=invert)
+
+                if query.operator == "and":
+                    lexemes &= new_lexeme
+                else:
+                    lexemes |= new_lexeme
+
+            return SearchQuery(lexemes, search_type="raw", config=config)
+
+        elif isinstance(query, Phrase):
+            return SearchQuery(query.query_string, search_type="phrase", config=config)
+
+        elif isinstance(query, Boost):
+            # Not supported
+            msg = "The Boost query is not supported by the PostgreSQL search backend."
+            warnings.warn(msg, RuntimeWarning)
+
+            return self.build_tsquery_content(
+                query.subquery, config=config, invert=invert
+            )
+
+        elif isinstance(query, Not):
+            return self.build_tsquery_content(
+                query.subquery, config=config, invert=not invert
+            )
+
+        elif isinstance(query, (And, Or)):
+            # If this part of the query is inverted, we swap the operator and
+            # pass down the inversion state to the child queries.
+            # This works thanks to De Morgan's law.
+            #
+            # For example, the following query:
+            #
+            #   Not(And(Term("A"), Term("B")))
+            #
+            # Is equivalent to:
+            #
+            #   Or(Not(Term("A")), Not(Term("B")))
+            #
+            # It's simpler to code it this way as we only need to store the
+            # invert status of the terms rather than all the operators.
+
+            subquery_lexemes = [
+                self.build_tsquery_content(subquery, config=config, invert=invert)
+                for subquery in query.subqueries
+            ]
+
+            is_and = isinstance(query, And)
+
+            if invert:
+                is_and = not is_and
+
+            if is_and:
+                return reduce(lambda a, b: a & b, subquery_lexemes)
+            else:
+                return reduce(lambda a, b: a | b, subquery_lexemes)
+
+        raise NotImplementedError(
+            "`%s` is not supported by the PostgreSQL search backend."
+            % query.__class__.__name__
+        )
+
+    def build_tsquery(self, query, config=None):
+        return self.build_tsquery_content(query, config=config)
+
+    def build_tsrank(self, vector, query, config=None, boost=1.0):
+        if isinstance(query, (Phrase, PlainText, Not)):
+            rank_expression = SearchRank(
+                vector,
+                self.build_tsquery(query, config=config),
+                weights=self.sql_weights,
+            )
+
+            if boost != 1.0:
+                rank_expression *= boost
+
+            return rank_expression
+
+        elif isinstance(query, Boost):
+            boost *= query.boost
+            return self.build_tsrank(vector, query.subquery, config=config, boost=boost)
+
+        elif isinstance(query, And):
+            return (
+                MUL(
+                    1 + self.build_tsrank(vector, subquery, config=config, boost=boost)
+                    for subquery in query.subqueries
+                )
+                - 1
+            )
+
+        elif isinstance(query, Or):
+            return ADD(
+                self.build_tsrank(vector, subquery, config=config, boost=boost)
+                for subquery in query.subqueries
+            ) / (len(query.subqueries) or 1)
+
+        raise NotImplementedError(
+            "`%s` is not supported by the PostgreSQL search backend."
+            % query.__class__.__name__
+        )
+
+    def get_index_vectors(self, search_query):
+        return [
+            (F("index_entries__title"), F("index_entries__title_norm")),
+            (F("index_entries__body"), 1.0),
+        ]
+
+    def get_fields_vectors(self, search_query):
+        return [
+            (
+                SearchVector(
+                    field_lookup,
+                    config=search_query.config,
+                ),
+                search_field.boost,
+            )
+            for field_lookup, search_field in self.search_fields.items()
+        ]
+
+    def get_search_vectors(self, search_query):
+        if self.fields is None:
+            return self.get_index_vectors(search_query)
+
+        else:
+            return self.get_fields_vectors(search_query)
+
+    def _build_rank_expression(self, vectors, config):
+        rank_expressions = [
+            self.build_tsrank(vector, self.query, config=config) * boost
+            for vector, boost in vectors
+        ]
+
+        rank_expression = rank_expressions[0]
+        for other_rank_expression in rank_expressions[1:]:
+            rank_expression += other_rank_expression
+
+        return rank_expression
+
+    def search(self, config, start, stop, score_field=None):
+        # TODO: Handle MatchAll nested inside other search query classes.
+        if isinstance(self.query, MatchAll):
+            return self.queryset[start:stop]
+
+        elif isinstance(self.query, Not) and isinstance(self.query.subquery, MatchAll):
+            return self.queryset.none()
+
+        search_query = self.build_tsquery(self.query, config=config)
+        vectors = self.get_search_vectors(search_query)
+        rank_expression = self._build_rank_expression(vectors, config)
+
+        combined_vector = vectors[0][0]
+        for vector, boost in vectors[1:]:
+            combined_vector = combined_vector._combine(vector, "||", False)
+
+        queryset = self.queryset.annotate(_vector_=combined_vector).filter(
+            _vector_=search_query
+        )
+
+        if self.order_by_relevance:
+            queryset = queryset.order_by(rank_expression.desc(), "-pk")
+
+        elif not queryset.query.order_by:
+            # Adds a default ordering to avoid issue #3729.
+            queryset = queryset.order_by("-pk")
+            rank_expression = F("pk")
+
+        if score_field is not None:
+            queryset = queryset.annotate(**{score_field: rank_expression})
+
+        return queryset[start:stop]
+
+    def _process_lookup(self, field, lookup, value):
+        lhs = field.get_attname(self.queryset.model) + "__" + lookup
+        return Q(**{lhs: value})
+
+    def _connect_filters(self, filters, connector, negated):
+        if connector == "AND":
+            q = Q(*filters)
+
+        elif connector == "OR":
+            q = OR([Q(fil) for fil in filters])
+
+        else:
+            return
+
+        if negated:
+            q = ~q
+
+        return q
+
+
+class PostgresAutocompleteQueryCompiler(PostgresSearchQueryCompiler):
+    LAST_TERM_IS_PREFIX = True
+    TARGET_SEARCH_FIELD_TYPE = AutocompleteField
+
+    def get_config(self, backend):
+        return backend.autocomplete_config
+
+    def get_search_fields_for_model(self):
+        return self.queryset.model.get_autocomplete_search_fields()
+
+    def get_index_vectors(self, search_query):
+        return [(F("index_entries__autocomplete"), 1.0)]
+
+    def get_fields_vectors(self, search_query):
+        return [
+            (
+                SearchVector(
+                    field_lookup,
+                    config=search_query.config,
+                    weight="D",
+                ),
+                1.0,
+            )
+            for field_lookup, search_field in self.search_fields.items()
+        ]
+
+
+class PostgresSearchResults(BaseSearchResults):
+    def get_queryset(self, for_count=False):
+        if for_count:
+            start = None
+            stop = None
+        else:
+            start = self.start
+            stop = self.stop
+
+        return self.query_compiler.search(
+            self.query_compiler.get_config(self.backend),
+            start,
+            stop,
+            score_field=self._score_field,
+        )
+
+    def _do_search(self):
+        return list(self.get_queryset())
+
+    def _do_count(self):
+        return self.get_queryset(for_count=True).count()
+
+    supports_facet = True
+
+    def facet(self, field_name):
+        # Get field
+        field = self.query_compiler._get_filterable_field(field_name)
+        if field is None:
+            raise FilterFieldError(
+                'Cannot facet search results with field "'
+                + field_name
+                + "\". Please add index.FilterField('"
+                + field_name
+                + "') to "
+                + self.query_compiler.queryset.model.__name__
+                + ".search_fields.",
+                field_name=field_name,
+            )
+
+        query = self.query_compiler.search(
+            self.query_compiler.get_config(self.backend), None, None
+        )
+        results = (
+            query.values(field_name).annotate(count=Count("pk")).order_by("-count")
+        )
+
+        return OrderedDict(
+            [(result[field_name], result["count"]) for result in results]
+        )
+
+
+class PostgresSearchRebuilder:
+    def __init__(self, index):
+        self.index = index
+
+    def start(self):
+        self.index.delete_stale_entries()
+        return self.index
+
+    def finish(self):
+        self.index._refresh_title_norms(full=True)
+
+
+class PostgresSearchAtomicRebuilder(PostgresSearchRebuilder):
+    def __init__(self, index):
+        super().__init__(index)
+        self.transaction = transaction.atomic(using=index.db_alias)
+        self.transaction_opened = False
+
+    def start(self):
+        self.transaction.__enter__()
+        self.transaction_opened = True
+        return super().start()
+
+    def finish(self):
+        self.index._refresh_title_norms(full=True)
+
+        self.transaction.__exit__(None, None, None)
+        self.transaction_opened = False
+
+    def __del__(self):
+        # TODO: Implement a cleaner way to close the connection on failure.
+        if self.transaction_opened:
+            self.transaction.needs_rollback = True
+            self.finish()
+
+
+class PostgresSearchBackend(BaseSearchBackend):
+    query_compiler_class = PostgresSearchQueryCompiler
+    autocomplete_query_compiler_class = PostgresAutocompleteQueryCompiler
+    results_class = PostgresSearchResults
+    rebuilder_class = PostgresSearchRebuilder
+    atomic_rebuilder_class = PostgresSearchAtomicRebuilder
+
+    def __init__(self, params):
+        super().__init__(params)
+        self.index_name = params.get("INDEX", "default")
+        self.config = params.get("SEARCH_CONFIG")
+
+        # Use 'simple' config for autocomplete to disable stemming
+        # A good description for why this is important can be found at:
+        # https://www.postgresql.org/docs/9.1/datatype-textsearch.html#DATATYPE-TSQUERY
+        self.autocomplete_config = params.get("AUTOCOMPLETE_SEARCH_CONFIG", "simple")
+
+        if params.get("ATOMIC_REBUILD", False):
+            self.rebuilder_class = self.atomic_rebuilder_class
+
+    def get_index_for_model(self, model, db_alias=None):
+        return Index(self, db_alias)
+
+    def get_index_for_object(self, obj):
+        return self.get_index_for_model(obj._meta.model, obj._state.db)
+
+    def reset_index(self):
+        for connection in [
+            connection
+            for connection in connections.all()
+            if connection.vendor == "postgresql"
+        ]:
+            IndexEntry._default_manager.all()._raw_delete(using=connection.alias)
+
+    def add_type(self, model):
+        pass  # Not needed.
+
+    def refresh_index(self):
+        pass  # Not needed.
+
+    def add(self, obj):
+        self.get_index_for_object(obj).add_item(obj)
+
+    def add_bulk(self, model, obj_list):
+        if obj_list:
+            self.get_index_for_object(obj_list[0]).add_items(model, obj_list)
+
+    def delete(self, obj):
+        self.get_index_for_object(obj).delete_item(obj)
+
+
+SearchBackend = PostgresSearchBackend

env/lib/python3.10/site-packages/wagtail/search/backends/database/postgres/query.py

@@ -0,0 +1,83 @@
+from django.contrib.postgres.search import SearchQueryField
+from django.db.models.expressions import Expression, Value
+
+
+class LexemeCombinable(Expression):
+    BITAND = "&"
+    BITOR = "|"
+
+    def _combine(self, other, connector, reversed, node=None):
+        if not isinstance(other, LexemeCombinable):
+            raise TypeError(
+                f"Lexeme can only be combined with other Lexemes, got {type(other)}."
+            )
+        if reversed:
+            return CombinedLexeme(other, connector, self)
+        return CombinedLexeme(self, connector, other)
+
+    # On Combinable, these are not implemented to reduce confusion with Q. In
+    # this case we are actually (ab)using them to do logical combination so
+    # it's consistent with other usage in Django.
+    def bitand(self, other):
+        return self._combine(other, self.BITAND, False)
+
+    def bitor(self, other):
+        return self._combine(other, self.BITOR, False)
+
+    def __or__(self, other):
+        return self._combine(other, self.BITOR, False)
+
+    def __and__(self, other):
+        return self._combine(other, self.BITAND, False)
+
+
+class Lexeme(LexemeCombinable, Value):
+    _output_field = SearchQueryField()
+
+    def __init__(
+        self, value, output_field=None, *, invert=False, prefix=False, weight=None
+    ):
+        self.prefix = prefix
+        self.invert = invert
+        self.weight = weight
+        super().__init__(value, output_field=output_field)
+
+    def as_sql(self, compiler, connection):
+        param = "'%s'" % self.value.replace("'", "''").replace("\\", "\\\\")
+
+        template = "%s"
+
+        label = ""
+        if self.prefix:
+            label += "*"
+        if self.weight:
+            label += self.weight
+
+        if label:
+            param = f"{param}:{label}"
+        if self.invert:
+            param = f"!{param}"
+
+        return template, [param]
+
+
+class CombinedLexeme(LexemeCombinable):
+    _output_field = SearchQueryField()
+
+    def __init__(self, lhs, connector, rhs, output_field=None):
+        super().__init__(output_field=output_field)
+        self.connector = connector
+        self.lhs = lhs
+        self.rhs = rhs
+
+    def as_sql(self, compiler, connection):
+        value_params = []
+        lsql, params = compiler.compile(self.lhs)
+        value_params.extend(params)
+
+        rsql, params = compiler.compile(self.rhs)
+        value_params.extend(params)
+
+        combined_sql = f"({lsql} {self.connector} {rsql})"
+        combined_value = combined_sql % tuple(value_params)
+        return "%s", [combined_value]

env/lib/python3.10/site-packages/wagtail/search/backends/database/postgres/weights.py

@@ -0,0 +1,63 @@
+from itertools import zip_longest
+
+from django.apps import apps
+
+from wagtail.search.index import Indexed
+from wagtail.search.utils import get_search_fields
+
+# This file contains the implementation of weights for PostgreSQL tsvectors. Only PostgreSQL has support for them, so that's why we define them here.
+
+
+WEIGHTS = "ABCD"
+WEIGHTS_COUNT = len(WEIGHTS)
+# These are filled when apps are ready.
+BOOSTS_WEIGHTS = []
+WEIGHTS_VALUES = []
+
+
+def get_boosts():
+    boosts = set()
+    for model in apps.get_models():
+        if issubclass(model, Indexed):
+            for search_field in get_search_fields(model.get_search_fields()):
+                boost = search_field.boost
+                if boost is not None:
+                    boosts.add(boost)
+    return boosts
+
+
+def determine_boosts_weights(boosts=()):
+    if not boosts:
+        boosts = get_boosts()
+    boosts = sorted(boosts, reverse=True)
+    min_boost = boosts[-1]
+    if len(boosts) <= WEIGHTS_COUNT:
+        return list(zip_longest(boosts, WEIGHTS, fillvalue=min(min_boost, 0)))
+    max_boost = boosts[0]
+    boost_step = (max_boost - min_boost) / (WEIGHTS_COUNT - 1)
+    return [(max_boost - (i * boost_step), weight) for i, weight in enumerate(WEIGHTS)]
+
+
+def set_weights():
+    BOOSTS_WEIGHTS.extend(determine_boosts_weights())
+    weights = [w for w, c in BOOSTS_WEIGHTS]
+    min_weight = min(weights)
+    if min_weight <= 0:
+        if min_weight == 0:
+            min_weight = -0.1
+        weights = [w - min_weight for w in weights]
+    max_weight = max(weights)
+    WEIGHTS_VALUES.extend([w / max_weight for w in reversed(weights)])
+
+
+def get_weight(boost):
+    if boost is None:
+        return WEIGHTS[-1]
+    for max_boost, weight in BOOSTS_WEIGHTS:
+        if boost >= max_boost:
+            return weight
+    return weight
+
+
+def get_sql_weights():
+    return "{" + ",".join(map(str, WEIGHTS_VALUES)) + "}"

env/lib/python3.10/site-packages/wagtail/search/backends/database/sqlite/query.py

@@ -0,0 +1,294 @@
+from typing import Any, List, Tuple
+
+from django.db.backends.base.base import BaseDatabaseWrapper
+from django.db.models.expressions import CombinedExpression, Expression, Func, Value
+from django.db.models.fields import BooleanField, Field, FloatField
+from django.db.models.sql.compiler import SQLCompiler
+
+from wagtail.search.query import And, MatchAll, Not, Or, Phrase, PlainText, SearchQuery
+
+
+class BM25(Func):
+    function = "bm25"
+    output_field = FloatField()
+
+    def __init__(self):
+        expressions = ()
+        super().__init__(*expressions)
+
+    def as_sql(
+        self,
+        compiler: SQLCompiler,
+        connection: BaseDatabaseWrapper,
+        function=None,
+        template=None,
+    ):
+        sql, params = "bm25(wagtailsearch_indexentry_fts)", []
+        return sql, params
+
+
+class LexemeCombinable(Expression):
+    BITAND = "AND"
+    BITOR = "OR"
+
+    def _combine(self, other, connector, reversed, node=None):
+        if not isinstance(other, LexemeCombinable):
+            raise TypeError(
+                f"Lexeme can only be combined with other Lexemes, got {type(other)}."
+            )
+        if reversed:
+            return CombinedLexeme(other, connector, self)
+        return CombinedLexeme(self, connector, other)
+
+    # On Combinable, these are not implemented to reduce confusion with Q. In
+    # this case we are actually (ab)using them to do logical combination so
+    # it's consistent with other usage in Django.
+    def bitand(self, other):
+        return self._combine(other, self.BITAND, False)
+
+    def bitor(self, other):
+        return self._combine(other, self.BITOR, False)
+
+    def __or__(self, other):
+        return self._combine(other, self.BITOR, False)
+
+    def __and__(self, other):
+        return self._combine(other, self.BITAND, False)
+
+
+class SearchQueryField(Field):
+    def db_type(self, connection):
+        return None
+
+
+class Lexeme(LexemeCombinable, Value):
+    _output_field = SearchQueryField()
+
+    def __init__(self, value, output_field=None, *, prefix=False, weight=None):
+        self.prefix = prefix
+        self.weight = weight
+        super().__init__(value, output_field=output_field)
+
+    def as_sql(self, compiler, connection):
+        param = self.value.replace("'", "''").replace("\\", "\\\\")
+
+        if self.prefix:
+            template = '"%s"*'
+        else:
+            template = '"%s"'
+
+        return template, [param]
+
+
+class CombinedLexeme(LexemeCombinable):
+    _output_field = SearchQueryField()
+
+    def __init__(self, lhs, connector, rhs, output_field=None):
+        super().__init__(output_field=output_field)
+        self.connector = connector
+        self.lhs = lhs
+        self.rhs = rhs
+
+    def as_sql(self, compiler, connection):
+        value_params = []
+        lsql, params = compiler.compile(self.lhs)
+        value_params.extend(params)
+
+        rsql, params = compiler.compile(self.rhs)
+        value_params.extend(params)
+
+        combined_sql = f"{lsql} {self.connector} {rsql}"
+        combined_value = combined_sql % tuple(value_params)
+        return "%s", [combined_value]
+
+
+class SearchQueryCombinable:
+    BITAND = "AND"
+    BITOR = "OR"
+
+    def _combine(self, other, connector: str, reversed: bool = False):
+        if not isinstance(other, SearchQueryCombinable):
+            raise TypeError(
+                "SearchQuery can only be combined with other SearchQuery "
+                "instances, got %s." % type(other).__name__
+            )
+        if reversed:
+            return CombinedSearchQueryExpression(other, connector, self)
+        return CombinedSearchQueryExpression(self, connector, other)
+
+    # On Combinable, these are not implemented to reduce confusion with Q. In
+    # this case we are actually (ab)using them to do logical combination so
+    # it's consistent with other usage in Django.
+    def __or__(self, other):
+        return self._combine(other, self.BITOR, False)
+
+    def __ror__(self, other):
+        return self._combine(other, self.BITOR, True)
+
+    def __and__(self, other):
+        return self._combine(other, self.BITAND, False)
+
+    def __rand__(self, other):
+        return self._combine(other, self.BITAND, True)
+
+
+class SearchQueryExpression(SearchQueryCombinable, Expression):
+    def __init__(self, value: LexemeCombinable, using=None, **extra):
+        super().__init__(output_field=SearchQueryField())
+        self.using = using
+        self.extra = extra
+        if isinstance(value, str):  # If the value is a string, we assume it's a phrase
+            self.value = Value(
+                '"%s"' % value
+            )  # We wrap it in quotes to make sure it's parsed as a phrase
+        else:  # Otherwise, we assume it's a lexeme
+            self.value = value
+
+    def as_sql(
+        self,
+        compiler: SQLCompiler,
+        connection: BaseDatabaseWrapper,
+        **extra_context: Any,
+    ) -> Tuple[str, List[Any]]:
+        sql, params = compiler.compile(self.value)
+        return (sql, params)
+
+    def __repr__(self) -> str:
+        return self.value.__repr__()
+
+
+class CombinedSearchQueryExpression(SearchQueryCombinable, CombinedExpression):
+    def __init__(self, lhs, connector, rhs, output_field=None):
+        super().__init__(lhs, connector, rhs, output_field)
+
+    def __str__(self):
+        return "(%s)" % super().__str__()
+
+
+class MatchExpression(Expression):
+    filterable = True
+    template = (
+        "wagtailsearch_indexentry_fts MATCH %s"  # TODO: Can the table name be inferred?
+    )
+    output_field = BooleanField()
+
+    def __init__(self, columns: List[str], query: SearchQueryCombinable) -> None:
+        super().__init__(output_field=self.output_field)
+        self.columns = columns
+        self.query = query
+
+    def as_sql(self, compiler, connection):
+        joined_columns = " ".join(
+            self.columns
+        )  # The format of the columns is 'column1 column2'
+        compiled_query = compiler.compile(self.query)  # Compile the query to a string
+        formatted_query = compiled_query[0] % tuple(
+            compiled_query[1]
+        )  # Substitute the params in the query
+        params = [
+            "{{{column}}} : ({query})".format(
+                column=joined_columns, query=formatted_query
+            )
+        ]  # Build the full MATCH search query. It will be a parameter to the template, so no SQL injections are possible here.
+        return (self.template, params)
+
+    def __repr__(self):
+        return f"<MatchExpression: {self.columns!r} = {self.query!r}>"
+
+
+class AndNot(SearchQuery):
+    """
+    This is a binary search query, where there are two subqueries, and the search is done by searching the first, and excluding the second subquery.
+    For example, AndNot(X, Y) would be equivalent to doing And(X, Not(Y)), where X is the first subquery, and Y is the second subquery (the negated one).
+    This is done because the SQLite FTS5 module doesn't support the unary NOT operator.
+    """
+
+    def __init__(self, subquery_a: SearchQuery, subquery_b: SearchQuery):
+        self.subquery_a = subquery_a
+        self.subquery_b = subquery_b
+
+    def __repr__(self):
+        return f"<{repr(self.subquery_a)} AndNot {repr(self.subquery_b)}>"
+
+
+def normalize(search_query: SearchQuery) -> Tuple[SearchQuery]:
+    """
+    Turns this query into a normalized version.
+    For example, And(Not(PlainText("Arepa")), PlainText("Crepe")) would be turned into AndNot(PlainText("Crepe"), PlainText("Arepa")): "Crepe AND NOT Arepa".
+    This is done because we need to get the NOT operator to the front of the query, so it can be used in the search, because the SQLite FTS5 module doesn't support the unary NOT operator. This means that, in order to support the NOT operator, we need to match against the non-negated version of the query, and then return everything that is not in the results of the non-negated query.
+    """
+    if isinstance(search_query, Phrase):
+        return search_query  # We can't normalize a Phrase.
+    if isinstance(search_query, PlainText):
+        return search_query  # We can't normalize a PlainText.
+    if isinstance(search_query, And):
+        normalized_subqueries: List[SearchQuery] = [
+            normalize(subquery) for subquery in search_query.subqueries
+        ]  # This builds a list of normalized subqueries.
+
+        not_negated_subqueries = [
+            subquery
+            for subquery in normalized_subqueries
+            if not isinstance(subquery, Not)
+        ]  # All the non-negated subqueries.
+        not_negated_subqueries = [
+            subquery
+            for subquery in not_negated_subqueries
+            if not isinstance(subquery, MatchAll)
+        ]  # We can ignore all MatchAll SearchQueries here, because they are redundant.
+        negated_subqueries = [
+            subquery.subquery
+            for subquery in normalized_subqueries
+            if isinstance(subquery, Not)
+        ]
+
+        if (
+            negated_subqueries == []
+        ):  # If there are no negated subqueries, return an And(), now without the redundant MatchAll subqueries.
+            return And(not_negated_subqueries)
+
+        for subquery in (
+            negated_subqueries
+        ):  # If there's a negated MatchAll subquery, then nothing will get matched.
+            if isinstance(subquery, MatchAll):
+                return Not(MatchAll())
+
+        return AndNot(And(not_negated_subqueries), Or(negated_subqueries))
+    if isinstance(search_query, Or):
+        normalized_subqueries: List[SearchQuery] = [
+            normalize(subquery) for subquery in search_query.subqueries
+        ]  # This builds a list of (subquery, negated) tuples.
+
+        negated_subqueries = [
+            subquery.subquery
+            for subquery in normalized_subqueries
+            if isinstance(subquery, Not)
+        ]
+        if (
+            negated_subqueries == []
+        ):  # If there are no negated subqueries, return an Or().
+            return Or(normalized_subqueries)
+
+        for subquery in (
+            negated_subqueries
+        ):  # If there's a MatchAll subquery, then anything will get matched.
+            if isinstance(subquery, MatchAll):
+                return MatchAll()
+
+        not_negated_subqueries = [
+            subquery
+            for subquery in normalized_subqueries
+            if not isinstance(subquery, Not)
+        ]  # All the non-negated subqueries.
+        not_negated_subqueries = [
+            subquery
+            for subquery in not_negated_subqueries
+            if not isinstance(subquery, MatchAll)
+        ]  # We can ignore all MatchAll SearchQueries here, because they are redundant.
+
+        return AndNot(MatchAll(), And(negated_subqueries))
+    if isinstance(search_query, Not):
+        normalized = normalize(search_query.subquery)
+        return Not(normalized)  # Normalize the subquery, then invert it.
+    if isinstance(search_query, MatchAll):
+        return search_query  # We can't normalize a MatchAll.

env/lib/python3.10/site-packages/wagtail/search/backends/database/sqlite/sqlite.py

@@ -0,0 +1,707 @@
+from collections import OrderedDict
+from functools import reduce
+
+from django.db import DEFAULT_DB_ALIAS, NotSupportedError, connections, transaction
+from django.db.models import Avg, Count, F, Manager, Q, TextField
+from django.db.models.constants import LOOKUP_SEP
+from django.db.models.functions import Cast, Length
+from django.db.utils import OperationalError
+from django.utils.encoding import force_str
+from django.utils.functional import cached_property
+
+from ....index import AutocompleteField, RelatedFields, SearchField, get_indexed_models
+from ....models import IndexEntry, SQLiteFTSIndexEntry
+from ....query import And, MatchAll, Not, Or, Phrase, PlainText
+from ....utils import (
+    ADD,
+    MUL,
+    OR,
+    get_content_type_pk,
+    get_descendants_content_types_pks,
+)
+from ...base import (
+    BaseSearchBackend,
+    BaseSearchQueryCompiler,
+    BaseSearchResults,
+    FilterFieldError,
+)
+from .query import (
+    BM25,
+    AndNot,
+    Lexeme,
+    MatchExpression,
+    SearchQueryExpression,
+    normalize,
+)
+
+
+class ObjectIndexer:
+    """
+    Responsible for extracting data from an object to be inserted into the index.
+    """
+
+    def __init__(self, obj, backend):
+        self.obj = obj
+        self.search_fields = obj.get_search_fields()
+        self.config = backend.config
+
+    def prepare_value(self, value):
+        if isinstance(value, str):
+            return value
+
+        elif isinstance(value, list):
+            return ", ".join(self.prepare_value(item) for item in value)
+
+        elif isinstance(value, dict):
+            return ", ".join(self.prepare_value(item) for item in value.values())
+
+        return force_str(value)
+
+    def prepare_field(self, obj, field):
+        if isinstance(field, SearchField):
+            yield (field, self.prepare_value(field.get_value(obj)))
+
+        elif isinstance(field, AutocompleteField):
+            yield (field, self.prepare_value(field.get_value(obj)))
+
+        elif isinstance(field, RelatedFields):
+            sub_obj = field.get_value(obj)
+            if sub_obj is None:
+                return
+
+            if isinstance(sub_obj, Manager):
+                sub_objs = sub_obj.all()
+
+            else:
+                if callable(sub_obj):
+                    sub_obj = sub_obj()
+
+                sub_objs = [sub_obj]
+
+            for sub_obj in sub_objs:
+                for sub_field in field.fields:
+                    yield from self.prepare_field(sub_obj, sub_field)
+
+    @cached_property
+    def id(self):
+        """
+        Returns the value to use as the ID of the record in the index
+        """
+        return force_str(self.obj.pk)
+
+    @cached_property
+    def title(self):
+        """
+        Returns all values to index as "title". This is the value of all SearchFields that have the field_name 'title'
+        """
+        texts = []
+        for field in self.search_fields:
+            for current_field, value in self.prepare_field(self.obj, field):
+                if (
+                    isinstance(current_field, SearchField)
+                    and current_field.field_name == "title"
+                ):
+                    texts.append(value)
+
+        return " ".join(texts)
+
+    @cached_property
+    def body(self):
+        """
+        Returns all values to index as "body". This is the value of all SearchFields excluding the title
+        """
+        texts = []
+        for field in self.search_fields:
+            for current_field, value in self.prepare_field(self.obj, field):
+                if (
+                    isinstance(current_field, SearchField)
+                    and not current_field.field_name == "title"
+                ):
+                    texts.append(value)
+
+        return " ".join(texts)
+
+    @cached_property
+    def autocomplete(self):
+        """
+        Returns all values to index as "autocomplete". This is the value of all AutocompleteFields
+        """
+        texts = []
+        for field in self.search_fields:
+            for current_field, value in self.prepare_field(self.obj, field):
+                if isinstance(current_field, AutocompleteField):
+                    texts.append(value)
+
+        return " ".join(texts)
+
+    def as_vector(self, texts, for_autocomplete=False):
+        """
+        Converts an array of strings into a SearchVector that can be indexed.
+        """
+        texts = [(text.strip(), weight) for text, weight in texts]
+        texts = [(text, weight) for text, weight in texts if text]
+
+        return " ".join(texts)
+
+
+class Index:
+    def __init__(self, backend, db_alias=None):
+        self.backend = backend
+        self.name = self.backend.index_name
+        self.db_alias = DEFAULT_DB_ALIAS if db_alias is None else db_alias
+        self.connection = connections[self.db_alias]
+        if self.connection.vendor != "sqlite":
+            raise NotSupportedError(
+                "You must select a SQLite database " "to use the SQLite search backend."
+            )
+
+        self.entries = IndexEntry._default_manager.using(self.db_alias)
+
+    def add_model(self, model):
+        pass
+
+    def refresh(self):
+        pass
+
+    def _refresh_title_norms(self, full=False):
+        """
+        Refreshes the value of the title_norm field.
+
+        This needs to be set to 'lavg/ld' where:
+         - lavg is the average length of titles in all documents (also in terms)
+         - ld is the length of the title field in this document (in terms)
+        """
+
+        lavg = (
+            self.entries.annotate(title_length=Length("title"))
+            .filter(title_length__gt=0)
+            .aggregate(Avg("title_length"))["title_length__avg"]
+        )
+
+        if full:
+            # Update the whole table
+            # This is the most accurate option but requires a full table rewrite
+            # so we can't do it too often as it could lead to locking issues.
+            entries = self.entries
+
+        else:
+            # Only update entries where title_norm is 1.0
+            # This is the default value set on new entries.
+            # It's possible that other entries could have this exact value but there shouldn't be too many of those
+            entries = self.entries.filter(title_norm=1.0)
+
+        entries.annotate(title_length=Length("title")).filter(
+            title_length__gt=0
+        ).update(title_norm=lavg / F("title_length"))
+
+    def delete_stale_model_entries(self, model):
+        existing_pks = (
+            model._default_manager.using(self.db_alias)
+            .annotate(object_id=Cast("pk", TextField()))
+            .values("object_id")
+        )
+        content_types_pks = get_descendants_content_types_pks(model)
+        stale_entries = self.entries.filter(
+            content_type_id__in=content_types_pks
+        ).exclude(object_id__in=existing_pks)
+        stale_entries.delete()
+
+    def delete_stale_entries(self):
+        for model in get_indexed_models():
+            # We don’t need to delete stale entries for non-root models,
+            # since we already delete them by deleting roots.
+            if not model._meta.parents:
+                self.delete_stale_model_entries(model)
+
+    def add_item(self, obj):
+        self.add_items(obj._meta.model, [obj])
+
+    def add_items_update_then_create(self, content_type_pk, indexers):
+        ids_and_data = {}
+        for indexer in indexers:
+            ids_and_data[indexer.id] = (
+                indexer.title,
+                indexer.autocomplete,
+                indexer.body,
+            )
+
+        index_entries_for_ct = self.entries.filter(content_type_id=content_type_pk)
+        indexed_ids = frozenset(
+            index_entries_for_ct.filter(object_id__in=ids_and_data.keys()).values_list(
+                "object_id", flat=True
+            )
+        )
+        for indexed_id in indexed_ids:
+            title, autocomplete, body = ids_and_data[indexed_id]
+            index_entries_for_ct.filter(object_id=indexed_id).update(
+                title=title, autocomplete=autocomplete, body=body
+            )
+
+        to_be_created = []
+        for object_id in ids_and_data.keys():
+            if object_id not in indexed_ids:
+                title, autocomplete, body = ids_and_data[object_id]
+                to_be_created.append(
+                    IndexEntry(
+                        content_type_id=content_type_pk,
+                        object_id=object_id,
+                        title=title,
+                        autocomplete=autocomplete,
+                        body=body,
+                    )
+                )
+
+        self.entries.bulk_create(to_be_created)
+
+        self._refresh_title_norms()
+
+    def add_items(self, model, objs):
+        search_fields = model.get_search_fields()
+        if not search_fields:
+            return
+
+        indexers = [ObjectIndexer(obj, self.backend) for obj in objs]
+
+        # TODO: Delete unindexed objects while dealing with proxy models.
+        if indexers:
+            content_type_pk = get_content_type_pk(model)
+
+            update_method = self.add_items_update_then_create
+            update_method(content_type_pk, indexers)
+
+    def delete_item(self, item):
+        item.index_entries.all()._raw_delete(using=self.db_alias)
+
+    def __str__(self):
+        return self.name
+
+
+class SQLiteSearchRebuilder:
+    def __init__(self, index):
+        self.index = index
+
+    def start(self):
+        self.index.delete_stale_entries()
+        return self.index
+
+    def finish(self):
+        self.index._refresh_title_norms(full=True)
+
+
+class SQLiteSearchAtomicRebuilder(SQLiteSearchRebuilder):
+    def __init__(self, index):
+        super().__init__(index)
+        self.transaction = transaction.atomic(using=index.db_alias)
+        self.transaction_opened = False
+
+    def start(self):
+        self.transaction.__enter__()
+        self.transaction_opened = True
+        return super().start()
+
+    def finish(self):
+        self.index._refresh_title_norms(full=True)
+
+        self.transaction.__exit__(None, None, None)
+        self.transaction_opened = False
+
+    def __del__(self):
+        # TODO: Implement a cleaner way to close the connection on failure.
+        if self.transaction_opened:
+            self.transaction.needs_rollback = True
+            self.finish()
+
+
+class SQLiteSearchQueryCompiler(BaseSearchQueryCompiler):
+    DEFAULT_OPERATOR = "AND"
+    LAST_TERM_IS_PREFIX = False
+    TARGET_SEARCH_FIELD_TYPE = SearchField
+    FTS_TABLE_FIELDS = ["title", "body"]
+
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        local_search_fields = self.get_search_fields_for_model()
+
+        if self.fields is None:
+            # search over the fields defined on the current model
+            self.search_fields = local_search_fields
+        else:
+            # build a search_fields set from the passed definition,
+            # which may involve traversing relations
+            self.search_fields = {
+                field_lookup: self.get_search_field(
+                    field_lookup, fields=local_search_fields
+                )
+                for field_lookup in self.fields
+            }
+
+    def get_config(self, backend):
+        return backend.config
+
+    def get_search_fields_for_model(self):
+        return self.queryset.model.get_searchable_search_fields()
+
+    def get_search_field(self, field_lookup, fields=None):
+        if fields is None:
+            fields = self.search_fields
+
+        if LOOKUP_SEP in field_lookup:
+            field_lookup, sub_field_name = field_lookup.split(LOOKUP_SEP, 1)
+        else:
+            sub_field_name = None
+
+        for field in fields:
+            if (
+                isinstance(field, self.TARGET_SEARCH_FIELD_TYPE)
+                and field.field_name == field_lookup
+            ):
+                return field
+
+            # Note: Searching on a specific related field using
+            # `.search(fields=…)` is not yet supported by Wagtail.
+            # This method anticipates by already implementing it.
+            if isinstance(field, RelatedFields) and field.field_name == field_lookup:
+                return self.get_search_field(sub_field_name, field.fields)
+
+    def build_search_query_content(self, query, config=None):
+        """
+        Takes a SearchQuery and returns another SearchQuery object, which can be used to construct the query in SQL.
+        """
+        if isinstance(query, PlainText):
+            terms = query.query_string.split()
+            if not terms:
+                return None
+
+            last_term = terms.pop()
+
+            lexemes = Lexeme(
+                last_term, prefix=self.LAST_TERM_IS_PREFIX
+            )  # Combine all terms into a single lexeme.
+            for term in terms:
+                new_lexeme = Lexeme(term)
+
+                if query.operator.upper() == "AND":
+                    lexemes &= new_lexeme
+                else:
+                    lexemes |= new_lexeme
+
+            return SearchQueryExpression(lexemes, config=config)
+
+        elif isinstance(query, Phrase):
+            return SearchQueryExpression(query.query_string)
+
+        elif isinstance(query, AndNot):
+            # Combine the two sub-queries into a query of the form `(first) AND NOT (second)`.
+            subquery_a = self.build_search_query_content(
+                query.subquery_a, config=config
+            )
+            subquery_b = self.build_search_query_content(
+                query.subquery_b, config=config
+            )
+            combined_query = subquery_a._combine(subquery_b, "NOT")
+            return combined_query
+
+        elif isinstance(query, (And, Or)):
+            subquery_lexemes = [
+                self.build_search_query_content(subquery, config=config)
+                for subquery in query.subqueries
+            ]
+
+            is_and = isinstance(query, And)
+
+            if is_and:
+                return reduce(lambda a, b: a & b, subquery_lexemes)
+            else:
+                return reduce(lambda a, b: a | b, subquery_lexemes)
+
+        raise NotImplementedError(
+            "`%s` is not supported by the SQLite search backend."
+            % query.__class__.__name__
+        )
+
+    def build_search_query(self, query, config=None):
+        if isinstance(query, MatchAll):
+            return query
+        if isinstance(query, Not):
+            unwrapped_query = query.subquery
+            built_query = Not(
+                self.build_search_query(unwrapped_query, config=config)
+            )  # We don't take the Not operator into account.
+        else:
+            built_query = self.build_search_query_content(query, config=config)
+        return built_query
+
+    def build_tsrank(self, vector, query, config=None, boost=1.0):
+        if isinstance(query, (Phrase, PlainText, Not)):
+            rank_expression = BM25()
+
+            if boost != 1.0:
+                rank_expression *= boost
+
+            return rank_expression
+
+        elif isinstance(query, And):
+            return (
+                MUL(
+                    1 + self.build_tsrank(vector, subquery, config=config, boost=boost)
+                    for subquery in query.subqueries
+                )
+                - 1
+            )
+
+        elif isinstance(query, Or):
+            return ADD(
+                self.build_tsrank(vector, subquery, config=config, boost=boost)
+                for subquery in query.subqueries
+            ) / (len(query.subqueries) or 1)
+
+        raise NotImplementedError(
+            "`%s` is not supported by the SQLite search backend."
+            % query.__class__.__name__
+        )
+
+    def get_index_vectors(self):
+        return [
+            (F("index_entries__title"), F("index_entries__title_norm")),
+            (F("index_entries__body"), 1.0),
+        ]
+
+    def get_search_vectors(self):
+        return self.get_index_vectors()
+
+    def _build_rank_expression(self, vectors, config):
+        # TODO: Come up with my own expression class that compiles down to bm25
+
+        rank_expressions = [
+            self.build_tsrank(vector, self.query, config=config) * boost
+            for vector, boost in vectors
+        ]
+
+        rank_expression = rank_expressions[0]
+        for other_rank_expression in rank_expressions[1:]:
+            rank_expression += other_rank_expression
+
+        return rank_expression
+
+    def search(self, config, start, stop, score_field=None):
+        normalized_query = normalize(self.query)
+
+        if isinstance(normalized_query, MatchAll):
+            return self.queryset[start:stop]
+
+        elif isinstance(normalized_query, Not) and isinstance(
+            normalized_query.subquery, MatchAll
+        ):
+            return self.queryset.none()
+
+        if isinstance(normalized_query, Not):
+            normalized_query = normalized_query.subquery
+            negated = True
+        else:
+            negated = False
+
+        search_query = self.build_search_query(
+            normalized_query, config=config
+        )  # We build a search query here, for example: "%s MATCH '(hello AND world)'"
+        vectors = self.get_search_vectors()
+        rank_expression = self._build_rank_expression(vectors, config)
+
+        combined_vector = vectors[
+            0
+        ][
+            0
+        ]  # We create a combined vector for the search results queryset. We start with the first vector and build from there.
+        for vector, boost in vectors[1:]:
+            combined_vector = combined_vector._combine(
+                vector, " ", False
+            )  # We add the subsequent vectors to the combined vector.
+
+        # Build the FTS match expression.
+        expr = MatchExpression(self.fields or self.FTS_TABLE_FIELDS, search_query)
+        # Perform the FTS search. We'll get entries in the SQLiteFTSIndexEntry model.
+        objs = (
+            SQLiteFTSIndexEntry.objects.filter(expr)
+            .select_related("index_entry")
+            .filter(
+                index_entry__content_type__in=get_descendants_content_types_pks(
+                    self.queryset.model
+                )
+            )
+        )
+
+        if self.order_by_relevance:
+            objs = objs.order_by(BM25().desc())
+        elif not objs.query.order_by:
+            # Adds a default ordering to avoid issue #3729.
+            queryset = objs.order_by("-pk")
+            rank_expression = F("pk")
+
+        from django.db import connection
+        from django.db.models.sql.subqueries import InsertQuery
+
+        compiler = InsertQuery(IndexEntry).get_compiler(connection=connection)
+
+        try:
+            obj_ids = [
+                obj.index_entry.object_id for obj in objs
+            ]  # Get the IDs of the objects that matched. They're stored in the IndexEntry model, so we need to get that first.
+        except OperationalError as e:
+            raise OperationalError(
+                str(e)
+                + " The original query was: "
+                + compiler.compile(objs.query)[0]
+                + str(compiler.compile(objs.query)[1])
+            ) from e
+
+        if not negated:
+            queryset = self.queryset.filter(
+                id__in=obj_ids
+            )  # We need to filter the source queryset to get the objects that matched the search query.
+        else:
+            queryset = self.queryset.exclude(
+                id__in=obj_ids
+            )  # We exclude the objects that matched the search query from the source queryset, if the query is negated.
+
+        if score_field is not None:
+            queryset = queryset.annotate(**{score_field: rank_expression})
+
+        return queryset[start:stop]
+
+    def _process_lookup(self, field, lookup, value):
+        lhs = field.get_attname(self.queryset.model) + "__" + lookup
+        return Q(**{lhs: value})
+
+    def _connect_filters(self, filters, connector, negated):
+        if connector == "AND":
+            q = Q(*filters)
+
+        elif connector == "OR":
+            q = OR([Q(fil) for fil in filters])
+
+        else:
+            return
+
+        if negated:
+            q = ~q
+
+        return q
+
+
+class SQLiteAutocompleteQueryCompiler(SQLiteSearchQueryCompiler):
+    LAST_TERM_IS_PREFIX = True
+    TARGET_SEARCH_FIELD_TYPE = AutocompleteField
+    FTS_TABLE_FIELDS = ["autocomplete"]
+
+    def get_config(self, backend):
+        return backend.autocomplete_config
+
+    def get_search_fields_for_model(self):
+        return self.queryset.model.get_autocomplete_search_fields()
+
+    def get_index_vectors(self):
+        return [(F("index_entries__autocomplete"), 1.0)]
+
+
+class SQLiteSearchResults(BaseSearchResults):
+    def get_queryset(self, for_count=False):
+        if for_count:
+            start = None
+            stop = None
+        else:
+            start = self.start
+            stop = self.stop
+
+        return self.query_compiler.search(
+            self.query_compiler.get_config(self.backend),
+            start,
+            stop,
+            score_field=self._score_field,
+        )
+
+    def _do_search(self):
+        return list(self.get_queryset())
+
+    def _do_count(self):
+        return self.get_queryset(for_count=True).count()
+
+    supports_facet = True
+
+    def facet(self, field_name):
+        # Get field
+        field = self.query_compiler._get_filterable_field(field_name)
+        if field is None:
+            raise FilterFieldError(
+                'Cannot facet search results with field "'
+                + field_name
+                + "\". Please add index.FilterField('"
+                + field_name
+                + "') to "
+                + self.query_compiler.queryset.model.__name__
+                + ".search_fields.",
+                field_name=field_name,
+            )
+
+        query = self.query_compiler.search(
+            self.query_compiler.get_config(self.backend), None, None
+        )
+        results = (
+            query.values(field_name).annotate(count=Count("pk")).order_by("-count")
+        )
+
+        return OrderedDict(
+            [(result[field_name], result["count"]) for result in results]
+        )
+
+
+class SQLiteSearchBackend(BaseSearchBackend):
+    query_compiler_class = SQLiteSearchQueryCompiler
+    autocomplete_query_compiler_class = SQLiteAutocompleteQueryCompiler
+
+    results_class = SQLiteSearchResults
+    rebuilder_class = SQLiteSearchRebuilder
+    atomic_rebuilder_class = SQLiteSearchAtomicRebuilder
+
+    def __init__(self, params):
+        super().__init__(params)
+        self.index_name = params.get("INDEX", "default")
+
+        # SQLite backend currently has no config options
+        self.config = None
+        self.autocomplete_config = None
+
+        if params.get("ATOMIC_REBUILD", False):
+            self.rebuilder_class = self.atomic_rebuilder_class
+
+    def get_index_for_model(self, model, db_alias=None):
+        return Index(self, db_alias)
+
+    def get_index_for_object(self, obj):
+        return self.get_index_for_model(obj._meta.model, obj._state.db)
+
+    def reset_index(self):
+        for connection in [
+            connection
+            for connection in connections.all()
+            if connection.vendor == "sqlite"
+        ]:
+            IndexEntry._default_manager.all()._raw_delete(using=connection.alias)
+
+    def add_type(self, model):
+        pass  # Not needed.
+
+    def refresh_index(self):
+        pass  # Not needed.
+
+    def add(self, obj):
+        self.get_index_for_object(obj).add_item(obj)
+
+    def add_bulk(self, model, obj_list):
+        if obj_list:
+            self.get_index_for_object(obj_list[0]).add_items(model, obj_list)
+
+    def delete(self, obj):
+        self.get_index_for_object(obj).delete_item(obj)
+
+
+SearchBackend = SQLiteSearchBackend

env/lib/python3.10/site-packages/wagtail/search/backends/database/sqlite/utils.py

@@ -0,0 +1,35 @@
+import sqlite3
+
+from django.db import OperationalError
+
+
+def fts5_available():
+    # based on https://stackoverflow.com/a/36656216/1853523
+    if sqlite3.sqlite_version_info < (3, 19, 0):
+        # Prior to version 3.19, SQLite doesn't support FTS5 queries with
+        # column filters ('{column_1 column_2} : query'), which the sqlite
+        # fulltext backend needs
+        return False
+
+    tmp_db = sqlite3.connect(":memory:")
+    try:
+        tmp_db.execute("CREATE VIRTUAL TABLE fts5test USING fts5 (data);")
+    except sqlite3.OperationalError:
+        return False
+    finally:
+        tmp_db.close()
+
+    return True
+
+
+def fts_table_exists():
+    from wagtail.search.models import SQLiteFTSIndexEntry
+
+    try:
+        # ignore result of query; we are only interested in the query failing,
+        # not the presence of index entries
+        SQLiteFTSIndexEntry.objects.exists()
+    except OperationalError:
+        return False
+
+    return True