"""Add composite (repo_id, name) index on musehub_branches.

get_branch_head_commit_id() does a point lookup WHERE repo_id = ? AND name = ?
on every push and fetch. Without a composite index this scans all branches for
the repo. list_branches_with_detail() also benefits: the composite index covers
both the WHERE clause and the ORDER BY name, eliminating an in-memory sort.

Revision ID: 0057
Revises: 0056
"""
from __future__ import annotations

from alembic import op

revision = "0057"
down_revision = "0056"
branch_labels = None
depends_on = None


def upgrade() -> None:
    op.create_index(
        "ix_musehub_branches_repo_name",
        "musehub_branches",
        ["repo_id", "name"],
    )
    # The composite index on (repo_id, name) makes the single-column repo_id
    # index redundant — PostgreSQL can satisfy any repo_id-only scan using the
    # leftmost prefix of the composite index.
    op.drop_index("ix_musehub_branches_repo_id", table_name="musehub_branches")


def downgrade() -> None:
    op.create_index(
        "ix_musehub_branches_repo_id",
        "musehub_branches",
        ["repo_id"],
    )
    op.drop_index("ix_musehub_branches_repo_name", table_name="musehub_branches")