get_top_queries fails on PostgreSQL ≤ 12: references non-existent column "stddev_exec_time" in pg_stat_statements

[ChristophorusReyhan]

When running get_top_queries against PostgreSQL 12 (and older) the query errors with:

Error: column "stddev_exec_time" does not exist
LINE 9:                         stddev_exec_time,
                                 ^

Example tool output:

╭───────────── ✅ Tool Response postgres-mcp_8000.get_top_queries ─────────────╮
│  Arguments:                                                                  │
│    { "limit": 20, "sort_by": "resources" }                                   │
│  Response:                                                                   │
│  Error resource-intensive queries: column "stddev_exec_time" does not exist  │
│  LINE 9:                         stddev_exec_time,                           │
│                                  ^                                           │
╰──────────────────────────────────────────────────────────────────────────────╯

Root cause:

• The stddev_exec_time column was added to pg_stat_statements in PostgreSQL 13. In PostgreSQL 12 and earlier the equivalent column is stddev_time. See PostgreSQL docs:
  • PostgreSQL 12 pg_stat_statements columns: https://www.postgresql.org/docs/12/pgstatstatements.html
  • PostgreSQL 13 pg_stat_statements columns: https://www.postgresql.org/docs/13/pgstatstatements.html