making more generic exception handling

python/alembic/data_science_dev/versions/2026_03_25-attach_partitions_to_posts.py

@@ -0,0 +1,80 @@
+"""Attach all partition tables to the posts parent table.
+
+Alembic autogenerate creates partition tables as standalone tables but does not
+emit the ALTER TABLE ... ATTACH PARTITION statements needed for PostgreSQL to
+route inserts to the correct partition.
+
+Revision ID: a1b2c3d4e5f6
+Revises: 605b1794838f
+Create Date: 2026-03-25 10:00:00.000000
+
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from alembic import op
+from sqlalchemy import text
+
+from python.orm import DataScienceDevBase
+from python.orm.data_science_dev.posts.partitions import (
+    PARTITION_END_YEAR,
+    PARTITION_START_YEAR,
+    iso_weeks_in_year,
+    week_bounds,
+)
+
+if TYPE_CHECKING:
+    from collections.abc import Sequence
+
+# revision identifiers, used by Alembic.
+revision: str = "a1b2c3d4e5f6"
+down_revision: str | None = "605b1794838f"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+schema = DataScienceDevBase.schema_name
+
+ALREADY_ATTACHED_QUERY = text("""
+    SELECT inhrelid::regclass::text
+    FROM pg_inherits
+    WHERE inhparent = :parent::regclass
+""")
+
+
+def upgrade() -> None:
+    """Attach all weekly partition tables to the posts parent table."""
+    connection = op.get_bind()
+    already_attached = {
+        row[0]
+        for row in connection.execute(
+            ALREADY_ATTACHED_QUERY, {"parent": f"{schema}.posts"}
+        )
+    }
+
+    for year in range(PARTITION_START_YEAR, PARTITION_END_YEAR + 1):
+        for week in range(1, iso_weeks_in_year(year) + 1):
+            table_name = f"posts_{year}_{week:02d}"
+            qualified_name = f"{schema}.{table_name}"
+            if qualified_name in already_attached:
+                continue
+            start, end = week_bounds(year, week)
+            start_str = start.strftime("%Y-%m-%d %H:%M:%S")
+            end_str = end.strftime("%Y-%m-%d %H:%M:%S")
+            op.execute(
+                f"ALTER TABLE {schema}.posts "
+                f"ATTACH PARTITION {qualified_name} "
+                f"FOR VALUES FROM ('{start_str}') TO ('{end_str}')"
+            )
+
+
+def downgrade() -> None:
+    """Detach all weekly partition tables from the posts parent table."""
+    for year in range(PARTITION_START_YEAR, PARTITION_END_YEAR + 1):
+        for week in range(1, iso_weeks_in_year(year) + 1):
+            table_name = f"posts_{year}_{week:02d}"
+            op.execute(
+                f"ALTER TABLE {schema}.posts "
+                f"DETACH PARTITION {schema}.{table_name}"
+            )