Add missing index on rom_files(rom_id) to fix slow game listing on large ROM sets

[Copilot]

On large libraries (60k+ ROMs), listing games per platform was taking 4500ms+ due to a sequential scan on rom_files when joining to roms. The FK column rom_files.rom_id had no index — only the PK id was indexed.

Note: roms(platform_id) is already covered by the existing composite index idx_roms_platform_id_fs_name (leftmost-prefix).

Changes

• models/rom.py — Added __table_args__ to RomFile with idx_rom_files_rom_id index on rom_id
• alembic/versions/0079_add_rom_files_rom_id_index.py — Migration to create the index on existing databases

class RomFile(BaseModel):
    __tablename__ = "rom_files"

    __table_args__ = (Index("idx_rom_files_rom_id", "rom_id"),)

[Copilot]

Pull request overview

Adds an explicit DB index on rom_files.rom_id to eliminate slow sequential scans when joining rom_files to roms for large libraries, improving game listing performance.

Changes:

• Add SQLAlchemy model-level index idx_rom_files_rom_id on RomFile.rom_id.
• Add Alembic migration to create/drop the same index on existing databases.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
backend/models/rom.py	Defines idx_rom_files_rom_id on rom_files(rom_id) at the ORM/schema level.
backend/alembic/versions/0079_add_rom_files_rom_id_index.py	Creates the rom_files(rom_id) index for existing installations (with downgrade).

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[github-actions]

Test Results (mariadb)

1 243 tests   1 243 ✅  3m 50s ⏱️
    1 suites      0 💤
    1 files        0 ❌

Results for commit ce5624b.

[github-actions]

☂️ Python Coverage

current status: ✅

Overall Coverage

Lines	Covered	Coverage	Threshold	Status
16038	10896	68%	0%	🟢

New Files

No new covered files...

Modified Files

File	Coverage	Status
backend/models/rom.py	91%	🟢
TOTAL	91%	🟢

updated for commit: ce5624b by action🐍

[github-actions]

Test Results (postgresql)

1 243 tests   1 243 ✅  3m 52s ⏱️
    1 suites      0 💤
    1 files        0 ❌

Results for commit ce5624b.