chore: add composite index for journals (pypi#17404)

In admin UI we fetch the 50 latest, so create a composite index that
serves that use case.

Signed-off-by: Mike Fiedler <[email protected]>

warehouse/migrations/versions/ed4cc2ef6b0f_create_composite_index_for_journals.py

@@ -0,0 +1,44 @@
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""
+Create composite index for journals
+
+Revision ID: ed4cc2ef6b0f
+Revises: 48a7b9ee15af
+Create Date: 2025-01-13 19:08:43.774259
+"""
+
+import sqlalchemy as sa
+
+from alembic import op
+
+revision = "ed4cc2ef6b0f"
+down_revision = "5bc11bd312e5"
+
+
+def upgrade():
+    op.get_bind().commit()
+    with op.get_context().autocommit_block():
+        op.execute("SET lock_timeout = 4000")
+        op.execute("SET statement_timeout = 5000")
+        op.create_index(
+            "journals_submitted_by_and_reverse_date_idx",
+            "journals",
+            ["submitted_by", sa.text("submitted_date DESC")],
+            unique=False,
+            if_not_exists=True,
+            postgresql_concurrently=True,
+        )
+
+
+def downgrade():
+    op.drop_index("journals_submitted_by_and_reverse_date_idx", table_name="journals")

warehouse/packaging/models.py

@@ -998,6 +998,13 @@ def __table_args__(cls):  # noqa
             Index("journals_version_idx", "version"),
             Index("journals_submitted_by_idx", "submitted_by"),
             Index("journals_submitted_date_id_idx", cls.submitted_date, cls.id),
+            # Composite index for journals to be able to sort by
+            # `submitted_by`, and `submitted_date` in descending order.
+            Index(
+                "journals_submitted_by_and_reverse_date_idx",
+                cls._submitted_by,
+                cls.submitted_date.desc(),
+            ),
         )
 
     id: Mapped[int] = mapped_column(primary_key=True)