Add concurrent relative_path index for content query testing

CHANGES/1641.misc

@@ -0,0 +1 @@
+* Add the shared `core_contentartifact.relative_path` `text_pattern_ops` index needed to test optimized content file, index.html, and directory-listing queries.

pulp_service/pulp_service/app/migrations/0024_contentartifact_relative_path_pattern_index.py

@@ -0,0 +1,64 @@
+from django.db import migrations
+
+_INDEX_NAME = "core_ca_relpath_pattern_idx"
+_INDEX_MARKER = "pulp-service:0024:core_ca_relpath_pattern_idx"
+_CREATE_INDEX_SQL = (
+    'CREATE INDEX CONCURRENTLY IF NOT EXISTS "core_ca_relpath_pattern_idx" '
+    'ON "core_contentartifact" USING btree ("relative_path" text_pattern_ops)'
+)
+_DROP_INDEX_SQL = 'DROP INDEX CONCURRENTLY IF EXISTS "core_ca_relpath_pattern_idx"'
+_COMMENT_INDEX_SQL = (
+    "COMMENT ON INDEX \"core_ca_relpath_pattern_idx\" IS 'pulp-service:0024:core_ca_relpath_pattern_idx'"
+)
+
+
+def _index_info(cursor):
+    cursor.execute(
+        """
+        SELECT pg_index.indisvalid, obj_description(indexrel.oid, 'pg_class')
+        FROM pg_class AS indexrel
+        JOIN pg_index ON pg_index.indexrelid = indexrel.oid
+        JOIN pg_namespace AS namespace ON namespace.oid = indexrel.relnamespace
+        WHERE indexrel.relname = %s AND namespace.nspname = current_schema()
+        """,
+        [_INDEX_NAME],
+    )
+    return cursor.fetchone()
+
+
+def create_relative_path_index(apps, schema_editor):  # noqa: ARG001
+    """Create the index without removing indexes owned by another migration."""
+    with schema_editor.connection.cursor() as cursor:
+        info = _index_info(cursor)
+        if info:
+            if not info[0]:
+                raise RuntimeError(f"Index {_INDEX_NAME!r} exists but is invalid; refusing to drop it automatically.")
+            return
+
+        # Multiple migration workers can safely race here: IF NOT EXISTS prevents a second
+        # physical index, and this migration never drops an index during forward application.
+        cursor.execute(_CREATE_INDEX_SQL)
+        # COMMENT provides durable ownership information for the reverse migration.
+        cursor.execute(_COMMENT_INDEX_SQL)
+
+
+def drop_relative_path_index(apps, schema_editor):  # noqa: ARG001
+    """Drop only an index created by this migration, leaving shared indexes intact."""
+    with schema_editor.connection.cursor() as cursor:
+        info = _index_info(cursor)
+        if info and info[1] == _INDEX_MARKER:
+            cursor.execute(_DROP_INDEX_SQL)
+
+
+class Migration(migrations.Migration):
+    """Add the shared index used by the optimized content-handler queries."""
+
+    atomic = False  # CREATE/DROP INDEX CONCURRENTLY cannot run in a transaction.
+
+    dependencies = [
+        ("service", "0023_backfill_domain_creator_role"),
+    ]
+
+    operations = [
+        migrations.RunPython(create_relative_path_index, drop_relative_path_index),
+    ]