perf: fetch table indexes for a schema in one query, not one per table

[geekypunk]

Problem

enrichColumnsWithKeyAndIndexMetadata called getTableIndexes once per table inside its loop. On a wide schema that is hundreds of serial round trips, and it re-runs for every caller that misses the databaseObjects cache.

Measured on a 567-table MySQL connection reached over an SSH tunnel, GET /api/connections/{id}/objects:

	cache miss	cached
before	152.66s / 196.30s (~270ms per table)	0.03–0.48s
after	1.09–1.50s	0.03–0.48s (unchanged)

Both pre-fix requests were abandoned by the client (nginx 499). Because there is no stampede guard, a second caller arriving during the first sweep starts its own full sweep — so retrying made it worse.

Fix

Mirrors what loadForeignKeyColumns already does one line above: fetch the whole schema once and group in memory.

Adds IntrospectionProvider.getAllTableIndexes with a default implementation that loops the existing per-table method, so a provider that does not override it is unchanged, plus overrides for both shipped providers:

• MySQL — one INFORMATION_SCHEMA.STATISTICS query scoped to a single TABLE_SCHEMA, so it stays bounded on a server hosting many databases.
• Postgres — the same joins and filters as the per-table query, with t.relname = ANY(?) in place of t.relname = ?.

Behaviour preserved

• Tables with no indexes map to an empty list, so callers can distinguish "no indexes" from "not scanned" without a per-table fallback.
• A provider returns no entry for a name it cannot resolve precisely, and the caller falls back to the per-table query. Postgres declines schema-qualified names for that reason; objects qualified with another database are never offered at all.
• A failed bulk fetch logs and falls back rather than dropping index flags.

Verification

• The Postgres form was diffed against the per-table form on a live database with EXCEPT ALL in both directions: 744 rows each, zero rows differing either way.
• Both engines exercised end to end with index flags still populated (MySQL: 760 columns with a single-column index and 375 composite, of 4588; Postgres: 32 and 2, of 128) and no fallback warnings logged.

🤖 Generated with Claude Code