Fun with contenttype and caching. Compare only the

queries spent on the documents themselves or else

src/documents/models.py

@@ -374,6 +374,7 @@ class Document(SoftDeleteModel, ModelWithOwner):  # type: ignore[django-manager-
         If the queryset already annotated ``effective_content``, that value is used.
         """
         # Here to avoid circular import
+        from documents.versioning import LATEST_VERSION_CONTENT_PREFETCH_ATTR
         from documents.versioning import sort_versions_newest_first
         from documents.versioning import versions_newest_first
 
@@ -383,6 +384,19 @@ class Document(SoftDeleteModel, ModelWithOwner):  # type: ignore[django-manager-
         if self.root_document_id is not None or self.pk is None:
             return self.content
 
+        latest_version_prefetch = getattr(
+            self,
+            LATEST_VERSION_CONTENT_PREFETCH_ATTR,
+            None,
+        )
+        if latest_version_prefetch is not None:
+            # Empty list means prefetch ran and found no versions — use own content.
+            return (
+                latest_version_prefetch[0].content
+                if latest_version_prefetch
+                else self.content
+            )
+
         prefetched_cache = getattr(self, "_prefetched_objects_cache", None)
         prefetched_versions = (
             prefetched_cache.get("versions")

src/documents/serialisers.py

@@ -89,6 +89,7 @@ from documents.templating.utils import convert_format_str_to_template_format
 from documents.templating.workflows import validate_workflow_template
 from documents.validators import uri_validator
 from documents.validators import url_validator
+from documents.versioning import has_prefetched_effective_content
 from documents.versioning import sort_versions_newest_first
 
 if TYPE_CHECKING:
@@ -1152,8 +1153,14 @@ class DocumentSerializer(
 
     def to_representation(self, instance):
         doc = super().to_representation(instance)
-        if "content" in self.fields and hasattr(instance, "effective_content"):
-            doc["content"] = getattr(instance, "effective_content") or ""
+        if "content" in self.fields and has_prefetched_effective_content(instance):
+            # Only resolve version-aware content when it's cheap: an SQL
+            # annotation or a versions prefetch is already on the instance.
+            # A caller that set up neither (e.g. TrashView, GlobalSearchView,
+            # which build their own querysets) gets the document's own,
+            # unresolved content instead of paying for an extra per-instance
+            # query -- same as before effective_content resolution existed.
+            doc["content"] = instance.get_effective_content() or ""
         if self.truncate_content and "content" in self.fields:
             doc["content"] = doc.get("content")[0:550]
         return doc

src/documents/tests/test_document_list_effective_content_annotation.py

@@ -0,0 +1,457 @@
+from __future__ import annotations
+
+from types import SimpleNamespace
+from typing import TYPE_CHECKING
+
+import pytest
+from django.db import connection
+from django.test.utils import CaptureQueriesContext
+from rest_framework import status
+
+from documents.models import Document
+from documents.tests.factories import DocumentFactory
+from documents.versioning import LATEST_VERSION_CONTENT_PREFETCH_ATTR
+from documents.versioning import has_prefetched_effective_content
+from documents.versioning import latest_version_content_prefetch
+from documents.views import DocumentViewSet
+
+if TYPE_CHECKING:
+    from rest_framework.test import APIClient
+
+
+class TestNeedsEffectiveContentAnnotation:
+    """
+    DocumentViewSet._needs_effective_content_annotation() decides whether
+    the effective_content correlated subquery is worth attaching to the
+    queryset at all -- see TestDocumentListEffectiveContentAnnotation below
+    for why. This only checks that decision's own logic (a plain query-param
+    membership test), not that Django/DRF's filtering machinery works.
+    """
+
+    @pytest.mark.parametrize(
+        ("params", "expected"),
+        [
+            ({}, False),
+            ({"ordering": "-added"}, False),
+            ({"tags__id__in": "1,2"}, False),
+            ({"search": ""}, False),
+            ({"search": "   "}, False),
+            ({"content__icontains": ""}, False),
+            ({"search": "foo"}, True),
+            ({"title_content": "foo"}, True),
+            ({"content__istartswith": "foo"}, True),
+            ({"content__iendswith": "foo"}, True),
+            ({"content__icontains": "foo"}, True),
+            ({"content__iexact": "foo"}, True),
+        ],
+    )
+    def test_detects_content_filter_params(
+        self,
+        params: dict[str, str],
+        expected: bool,  # noqa: FBT001
+    ) -> None:
+        """
+        GIVEN:
+            - A view bound to a request carrying the given query params
+        WHEN:
+            - Checking whether the effective_content annotation is needed
+        THEN:
+            - It is needed only for requests that actually filter on it
+        """
+        view = DocumentViewSet()
+        view.request = SimpleNamespace(query_params=params)
+
+        assert view._needs_effective_content_annotation() is expected
+
+
+class TestNeedsEffectiveContentPrefetch:
+    """
+    DocumentViewSet._needs_effective_content_prefetch() decides whether the
+    single-version content prefetch is worth attaching. It has to read the
+    `fields` param exactly the way get_serializer() does, or a request whose
+    response includes content ends up without the prefetch and pays
+    get_effective_content()'s per-instance fallback instead.
+    """
+
+    @pytest.mark.parametrize(
+        ("params", "expected"),
+        [
+            pytest.param({}, True, id="no-fields-param-keeps-every-field"),
+            pytest.param({"fields": ""}, True, id="blank-fields-keeps-every-field"),
+            pytest.param(
+                {"fields": "id,content"},
+                True,
+                id="content-among-requested-fields",
+            ),
+            pytest.param({"fields": "content"}, True, id="content-only"),
+            pytest.param({"fields": "id"}, False, id="content-not-requested"),
+            pytest.param(
+                {"fields": "id,title"},
+                False,
+                id="several-fields-without-content",
+            ),
+        ],
+    )
+    def test_detects_whether_content_can_reach_the_response(
+        self,
+        params: dict[str, str],
+        expected: bool,  # noqa: FBT001
+    ) -> None:
+        """
+        GIVEN:
+            - A view bound to a request carrying the given query params
+        WHEN:
+            - Checking whether the content prefetch is needed
+        THEN:
+            - It is needed exactly when get_serializer() would emit content,
+              which treats a blank `fields` the same as an absent one
+        """
+        view = DocumentViewSet()
+        view.request = SimpleNamespace(query_params=params)
+
+        assert view._needs_effective_content_prefetch() is expected
+
+
+@pytest.mark.django_db
+class TestDocumentListEffectiveContentAnnotation:
+    """
+    DocumentViewSet.get_queryset() only attaches the effective_content
+    correlated subquery when a request actually filters on it. Attaching it
+    unconditionally re-executes it once per candidate row before the page's
+    LIMIT is applied -- fine on SQLite/Postgres, but pathological on
+    MariaDB's default cardinality estimation for the root_document_id
+    self-join once candidate counts get large (see the root_document_id /
+    effective_content perf investigation).
+    """
+
+    def test_list_without_content_filter_skips_annotation_but_returns_latest_content(
+        self,
+        admin_client: APIClient,
+    ) -> None:
+        """
+        GIVEN:
+            - A root document whose latest version has different content
+        WHEN:
+            - Listing documents with no search/content-filter param
+        THEN:
+            - The response still reflects the latest version's content
+            - The database never evaluates effective_content per row
+        """
+        root = DocumentFactory(content="old-root-content")
+        DocumentFactory(
+            root_document=root,
+            version_index=1,
+            content="new-version-content",
+        )
+
+        with CaptureQueriesContext(connection) as ctx:
+            response = admin_client.get("/api/documents/?fields=id,content")
+
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data["results"] == [
+            {"id": root.id, "content": "new-version-content"},
+        ]
+        assert not any(
+            "effective_content" in query["sql"] for query in ctx.captured_queries
+        )
+
+    @pytest.mark.parametrize(
+        "fields_param",
+        [
+            pytest.param("", id="blank-fields"),
+            pytest.param("id,content", id="content-requested"),
+        ],
+    )
+    def test_content_resolves_without_a_query_per_document(
+        self,
+        admin_client: APIClient,
+        fields_param: str,
+    ) -> None:
+        """
+        GIVEN:
+            - One versioned root document, then two more
+        WHEN:
+            - Listing documents with a `fields` param that keeps content
+        THEN:
+            - Every root's content resolves to its latest version's
+            - The query count does not grow with the number of documents,
+              i.e. a blank `fields` does not skip the prefetch and fall back
+              to loading each root's deferred version content
+        """
+        first = DocumentFactory(content="first-root-content")
+        DocumentFactory(
+            root_document=first,
+            version_index=1,
+            content="first-version-content",
+        )
+
+        with CaptureQueriesContext(connection) as one_document:
+            response = admin_client.get(f"/api/documents/?fields={fields_param}")
+
+        assert response.status_code == status.HTTP_200_OK
+        assert [r["content"] for r in response.data["results"]] == [
+            "first-version-content",
+        ]
+
+        for index in range(2):
+            root = DocumentFactory(content=f"root-content-{index}")
+            DocumentFactory(
+                root_document=root,
+                version_index=1,
+                content=f"version-content-{index}",
+            )
+        with CaptureQueriesContext(connection) as three_documents:
+            response = admin_client.get(f"/api/documents/?fields={fields_param}")
+
+        assert response.status_code == status.HTTP_200_OK
+        assert sorted(r["content"] for r in response.data["results"]) == [
+            "first-version-content",
+            "version-content-0",
+            "version-content-1",
+        ]
+        assert len(_get_document_queries(three_documents)) == len(
+            _get_document_queries(one_document),
+        )
+
+    def test_list_without_content_field_skips_prefetch_and_omits_content(
+        self,
+        admin_client: APIClient,
+    ) -> None:
+        """
+        GIVEN:
+            - A versioned root document
+        WHEN:
+            - Listing documents without asking for content
+        THEN:
+            - Content is neither serialized nor resolved
+            - Nothing pays for the prefetch or the per-instance fallback
+        """
+        root = DocumentFactory(content="root-content")
+        DocumentFactory(
+            root_document=root,
+            version_index=1,
+            content="version-content",
+        )
+
+        with CaptureQueriesContext(connection) as ctx:
+            response = admin_client.get("/api/documents/?fields=id")
+
+        assert response.status_code == status.HTTP_200_OK
+        assert response.data["results"] == [{"id": root.id}]
+        assert _get_effective_content_fallback_queries(ctx) == []
+        # Only the list query itself reads a content column: no extra query
+        # for the skipped prefetch, none for a per-instance fallback
+        content_queries = [
+            query
+            for query in ctx.captured_queries
+            if '"documents_document"."content"' in query["sql"]
+        ]
+        assert len(content_queries) == 1
+
+    def test_latest_version_content_prefetch_carries_only_the_newest_version(
+        self,
+    ) -> None:
+        """
+        GIVEN:
+            - A root document with two versions
+        WHEN:
+            - Fetching the root through latest_version_content_prefetch()
+        THEN:
+            - The prefetch carries only the single newest version, not every
+              historical version's content (the whole point of not reusing
+              the metadata-only "versions" prefetch for this)
+        """
+        root = DocumentFactory(content="root-content")
+        DocumentFactory(
+            root_document=root,
+            version_index=1,
+            content="older-version-content",
+        )
+        DocumentFactory(
+            root_document=root,
+            version_index=2,
+            content="newest-version-content",
+        )
+
+        fetched_root = (
+            Document.objects.filter(pk=root.pk)
+            .prefetch_related(
+                latest_version_content_prefetch(),
+            )
+            .get()
+        )
+
+        latest = getattr(fetched_root, LATEST_VERSION_CONTENT_PREFETCH_ATTR)
+        assert [v.content for v in latest] == ["newest-version-content"]
+
+
+class TestHasPrefetchedEffectiveContent:
+    """
+    DocumentSerializer.to_representation() only calls get_effective_content()
+    when has_prefetched_effective_content() says it's cheap -- otherwise a
+    caller that never set up an annotation or prefetch (TrashView,
+    GlobalSearchView, which build their own querysets and don't display
+    content at all) would pay for a per-instance query nobody asked for.
+    """
+
+    def test_false_with_no_annotation_or_prefetch(self) -> None:
+        """
+        GIVEN:
+            - A document the ORM never annotated or prefetched for
+        WHEN:
+            - Asking whether its effective content is already resolved
+        THEN:
+            - It is not, so the serializer must leave it alone
+        """
+        document = DocumentFactory.build()
+
+        assert has_prefetched_effective_content(document) is False
+
+    def test_true_with_effective_content_annotation(self) -> None:
+        """
+        GIVEN:
+            - A document carrying the queryset's effective_content annotation
+        WHEN:
+            - Asking whether its effective content is already resolved
+        THEN:
+            - It is, straight off the annotation
+        """
+        document = DocumentFactory.build()
+        document.effective_content = "resolved"
+
+        assert has_prefetched_effective_content(document) is True
+
+    def test_true_with_lean_prefetch_attr_even_when_empty(self) -> None:
+        """
+        GIVEN:
+            - A document the lean content prefetch ran for, finding no versions
+        WHEN:
+            - Asking whether its effective content is already resolved
+        THEN:
+            - It is: an empty prefetch is an answer, not a missing one
+        """
+        document = DocumentFactory.build()
+        setattr(document, LATEST_VERSION_CONTENT_PREFETCH_ATTR, [])
+
+        assert has_prefetched_effective_content(document) is True
+
+    def test_true_with_metadata_versions_prefetch_cache(self) -> None:
+        """
+        GIVEN:
+            - A document carrying only the metadata "versions" prefetch
+        WHEN:
+            - Asking whether its effective content is already resolved
+        THEN:
+            - It is, via get_effective_content()'s prefetch-cache branch
+        """
+        document = DocumentFactory.build()
+        document._prefetched_objects_cache = {"versions": []}
+
+        assert has_prefetched_effective_content(document) is True
+
+
+def _get_document_queries(
+    ctx: CaptureQueriesContext,
+) -> list[dict[str, str]]:
+    """
+    The queries a list request spends on the documents themselves, i.e.
+    everything but the one-time django_content_type lookup guardian's
+    permission filtering makes. That lookup is process-cached, and the
+    autouse fixture in conftest clears the cache before every test, so it
+    lands in whichever request happens to run first and never repeats --
+    counting it makes a request look like it costs one query more than the
+    identical request after it.
+    """
+    return [q for q in ctx.captured_queries if '"django_content_type"' not in q["sql"]]
+
+
+def _get_effective_content_fallback_queries(
+    ctx: CaptureQueriesContext,
+) -> list[dict[str, str]]:
+    """
+    Document.get_effective_content()'s per-instance fallback (no annotation,
+    no prefetch) is a `.values_list("content", flat=True).first()` query --
+    a SELECT of just the content column. Distinct from get_versions()'s own,
+    unrelated per-instance metadata query (id/checksum/added/etc, no
+    content) run to build the "versions" response field, which isn't part
+    of what this test file covers.
+    """
+    return [
+        q
+        for q in ctx.captured_queries
+        if q["sql"].startswith('SELECT "documents_document"."content" FROM')
+    ]
+
+
+@pytest.mark.django_db
+class TestTrashAndGlobalSearchEffectiveContentIsNeverPerInstance:
+    """
+    TrashView and GlobalSearchView serialize Document instances with
+    DocumentSerializer too, but build their querysets independently of
+    DocumentViewSet.get_queryset(). TrashView doesn't display content at all,
+    so it keeps the document's own unresolved content; GlobalSearchView
+    annotates effective_content itself, so it shows the latest version's.
+    Neither should ever fall back to a per-instance query.
+    """
+
+    def test_trash_list_shows_unresolved_content_with_no_extra_query(
+        self,
+        admin_client: APIClient,
+    ) -> None:
+        """
+        GIVEN:
+            - A trashed root document whose own content differs from what a
+              version would have had (also trashed, deletion cascades)
+        WHEN:
+            - Listing trash
+        THEN:
+            - The response shows the document's own content
+            - Nothing ever queries for versions to resolve it
+        """
+        root = DocumentFactory(content="own-content")
+        DocumentFactory(
+            root_document=root,
+            version_index=1,
+            content="version-content",
+        )
+        root.delete()
+
+        with CaptureQueriesContext(connection) as ctx:
+            response = admin_client.get("/api/trash/")
+
+        assert response.status_code == status.HTTP_200_OK
+        [result] = [r for r in response.data["results"] if r["id"] == root.id]
+        assert result["content"] == "own-content"
+        assert _get_effective_content_fallback_queries(ctx) == []
+
+    def test_global_search_db_only_shows_latest_version_content_with_no_extra_query(
+        self,
+        admin_client: APIClient,
+    ) -> None:
+        """
+        GIVEN:
+            - A root document, findable by title, whose own content differs
+              from its latest version's
+        WHEN:
+            - Using the global search endpoint's db_only mode
+        THEN:
+            - The response shows the latest version's content, resolved by
+              GlobalSearchView's own effective_content annotation
+            - There is no per-instance fallback query
+        """
+        root = DocumentFactory(title="findme", content="own-content")
+        DocumentFactory(
+            root_document=root,
+            version_index=1,
+            content="version-content",
+        )
+
+        with CaptureQueriesContext(connection) as ctx:
+            response = admin_client.get(
+                "/api/search/?query=findme&db_only=true",
+            )
+
+        assert response.status_code == status.HTTP_200_OK
+        [result] = [d for d in response.data["documents"] if d["id"] == root.id]
+        assert result["content"] == "version-content"
+        assert _get_effective_content_fallback_queries(ctx) == []

src/documents/versioning.py

@@ -7,9 +7,12 @@ from typing import Any
 
 from django.db.models import F
 from django.db.models import OuterRef
+from django.db.models import Prefetch
 from django.db.models import QuerySet
 from django.db.models import Subquery
+from django.db.models import Window
 from django.db.models.functions import Coalesce
+from django.db.models.functions import RowNumber
 
 from documents.models import Document
 
@@ -46,6 +49,68 @@ def annotate_effective_content(documents: QuerySet[Document]) -> QuerySet[Docume
     )
 
 
+LATEST_VERSION_CONTENT_PREFETCH_ATTR = "_latest_version_content_prefetch"
+
+
+def latest_version_content_prefetch() -> Prefetch:
+    """
+    A Prefetch for Document.versions scoped to just the newest version's
+    content, for get_effective_content()'s fallback when no SQL annotation
+    is present.
+
+    Deliberately not merged into a metadata-only "versions" prefetch (the one
+    used for the serialized versions list): that one fetches every historical
+    version of every document, and pulling full OCR content for versions
+    nobody will read wastes DB transfer/memory at scale. This one is windowed
+    down to a single row per root, then bounded by Prefetch's own IN-list to
+    whatever page/result set it's attached to -- one cheap bulk query total,
+    not one per document and not one per version.
+    """
+    return Prefetch(
+        "versions",
+        queryset=(
+            Document.objects.filter(
+                root_document_id__isnull=False,
+                deleted_at__isnull=True,
+            )
+            .annotate(
+                rn=Window(
+                    RowNumber(),
+                    partition_by=F("root_document_id"),
+                    order_by=[
+                        F("version_index").desc(nulls_last=True),
+                        F("id").desc(),
+                    ],
+                ),
+            )
+            .filter(rn=1)
+            .only("id", "root_document_id", "content")
+        ),
+        to_attr=LATEST_VERSION_CONTENT_PREFETCH_ATTR,
+    )
+
+
+def has_prefetched_effective_content(document: Document) -> bool:
+    """
+    True if document.get_effective_content() can answer without an extra
+    per-instance query -- an SQL ``effective_content`` annotation, the lean
+    latest_version_content_prefetch(), or the metadata-only "versions"
+    prefetch is already present on the instance.
+
+    Callers that haven't set any of those up (e.g. views that build their
+    own querysets independently of DocumentViewSet.get_queryset(), like
+    TrashView or GlobalSearchView) intentionally don't pay for version-aware
+    content resolution -- see DocumentSerializer.to_representation(), which
+    uses this to decide whether to call get_effective_content() at all.
+    """
+    if hasattr(document, "effective_content"):
+        return True
+    if getattr(document, LATEST_VERSION_CONTENT_PREFETCH_ATTR, None) is not None:
+        return True
+    prefetched_cache = getattr(document, "_prefetched_objects_cache", None)
+    return isinstance(prefetched_cache, dict) and "versions" in prefetched_cache
+
+
 def sort_versions_newest_first(documents: list[Document]) -> list[Document]:
     """
     Same sorting as versions_newest_first()

src/documents/views.py

@@ -36,7 +36,6 @@ from django.db.migrations.recorder import MigrationRecorder
 from django.db.models import Avg
 from django.db.models import Case
 from django.db.models import Count
-from django.db.models import F
 from django.db.models import IntegerField
 from django.db.models import Max
 from django.db.models import Model
@@ -137,12 +136,14 @@ from documents.filters import CustomFieldFilterSet
 from documents.filters import DocumentFilterSet
 from documents.filters import DocumentsOrderingFilter
 from documents.filters import DocumentTypeFilterSet
+from documents.filters import EffectiveContentFilter
 from documents.filters import PaperlessTaskFilterSet
 from documents.filters import PermittedObjectsFilter
 from documents.filters import ShareLinkBundleFilterSet
 from documents.filters import ShareLinkFilterSet
 from documents.filters import StoragePathFilterSet
 from documents.filters import TagFilterSet
+from documents.filters import TitleContentFilter
 from documents.mail import EmailAttachment
 from documents.mail import send_email
 from documents.matching import match_correspondents
@@ -236,6 +237,7 @@ from documents.versioning import annotate_effective_content
 from documents.versioning import get_latest_version_for_root
 from documents.versioning import get_request_version_param
 from documents.versioning import get_root_document
+from documents.versioning import latest_version_content_prefetch
 from documents.versioning import resolve_requested_version_for_root
 from documents.versioning import versions_newest_first
 from paperless import version
@@ -1083,12 +1085,59 @@ class DocumentViewSet(
             ],
         }
 
-    def get_queryset(self):
-        latest_version_content = Subquery(
-            versions_newest_first(
-                Document.objects.filter(root_document=OuterRef("pk")),
-            ).values("content")[:1],
+    @classmethod
+    def _content_filter_params(cls) -> tuple[str, ...]:
+        """
+        Query params whose filtering needs effective_content evaluated in SQL
+        against every candidate row -- see
+        _needs_effective_content_annotation(). Derived rather than
+        hand-maintained so a new content-filtering param counts automatically.
+        """
+        params = [
+            name
+            for name, f in DocumentFilterSet.declared_filters.items()
+            if isinstance(f, (TitleContentFilter, EffectiveContentFilter))
+        ]
+        if "effective_content" in cls.search_fields:
+            params.append(SearchFilter().search_param)
+        return tuple(params)
+
+    def _needs_effective_content_annotation(self) -> bool:
+        # effective_content is a per-row correlated subquery resolving each
+        # document's latest version. Filtering *on* it forces the database to
+        # evaluate it for every candidate row before reaching the LIMIT, which
+        # the root_document_id self-join makes pathological on MariaDB
+        # specifically once real candidate counts get large; otherwise the
+        # "versions" prefetch + Document.get_effective_content() resolves only
+        # the page that survives pagination. Every param here is deprecated in
+        # favor of the Tantivy-backed search endpoint (see filters.py's
+        # TitleContentFilter/EffectiveContentFilter docs), so pay that cost
+        # only when one is actually used. Blank values don't count, matching
+        # how those filters themselves no-op on them -- an empty `?search=`
+        # applies no predicate.
+        params = self.request.query_params
+        return any(
+            params.get(param, "").strip() for param in self._content_filter_params()
         )
+
+    def _requested_fields(self) -> list[str] | None:
+        # The sparse-fieldset `fields` param, as DynamicFieldsModelSerializer
+        # wants it: None means "no restriction, serialize everything", which
+        # a blank value means too. get_queryset() and get_serializer() both
+        # branch on this, and they have to read it identically -- a queryset
+        # that skips the content prefetch for a response that still
+        # serializes content reintroduces get_effective_content()'s
+        # per-instance fallback.
+        fields_param = self.request.query_params.get("fields")
+        return fields_param.split(",") if fields_param else None
+
+    def _needs_effective_content_prefetch(self) -> bool:
+        # The prefetch spares get_effective_content() a per-instance fallback
+        # query, but only earns itself when content can reach the response.
+        fields = self._requested_fields()
+        return fields is None or "content" in fields
+
+    def get_queryset(self):
         # A correlated subquery avoids the LEFT JOIN + Count() this used to
         # be, which forced a GROUP BY aggregate over every matching document
         # before the query could even be sorted or limited.
@@ -1108,40 +1157,43 @@ class DocumentViewSet(
         # ObjectFilter.filter(). A blanket .distinct() here forces the
         # database to fully sort and dedupe every visible document before
         # it can apply LIMIT, which is disastrous at scale.
-        return (
+        prefetches = [
+            Prefetch(
+                "versions",
+                queryset=Document.objects.only(
+                    "id",
+                    "added",
+                    "checksum",
+                    "version_label",
+                    "root_document_id",
+                    "version_index",
+                ),
+            ),
+            "tags",
+            Prefetch(
+                "custom_fields",
+                queryset=CustomFieldInstance.objects.select_related("field"),
+            ),
+            # NotesSerializer nests the author, this avoids query per note
+            Prefetch("notes", queryset=Note.objects.select_related("user")),
+        ]
+        if self._needs_effective_content_prefetch():
+            prefetches.append(latest_version_content_prefetch())
+        queryset = (
             Document.objects.filter(root_document__isnull=True)
             .order_by("-created", "-id")
-            .annotate(effective_content=Coalesce(latest_version_content, F("content")))
             .annotate(num_notes=Coalesce(note_count, 0))
             .select_related("correspondent", "storage_path", "document_type", "owner")
-            .prefetch_related(
-                Prefetch(
-                    "versions",
-                    queryset=Document.objects.only(
-                        "id",
-                        "added",
-                        "checksum",
-                        "version_label",
-                        "root_document_id",
-                        "version_index",
-                    ),
-                ),
-                "tags",
-                Prefetch(
-                    "custom_fields",
-                    queryset=CustomFieldInstance.objects.select_related("field"),
-                ),
-                # NotesSerializer nests the author, this avoids query per note
-                Prefetch("notes", queryset=Note.objects.select_related("user")),
-            )
+            .prefetch_related(*prefetches)
         )
+        if self._needs_effective_content_annotation():
+            queryset = annotate_effective_content(queryset)
+        return queryset
 
     def get_serializer(self, *args, **kwargs):
-        fields_param = self.request.query_params.get("fields", None)
-        fields = fields_param.split(",") if fields_param else None
         truncate_content = self.request.query_params.get("truncate_content", "False")
         kwargs.setdefault("context", self.get_serializer_context())
-        kwargs.setdefault("fields", fields)
+        kwargs.setdefault("fields", self._requested_fields())
         kwargs.setdefault("truncate_content", truncate_content.lower() in ["true", "1"])
         try:
             full_perms = get_boolean(