chore(observe): drop dead pg_stat_activity scrape path#599
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The postgres_query()-based pg_stat_activity scrape added in #598 silently no-ops in our DuckDB build and never populates the duckgres_ducklake_metadata_connections gauge. Remove it (and the gauge) rather than leave dead code that masks a real "no data" signal. Aurora-side connection / query activity is already attributable to duckgres via the application_name we tag at ATTACH time, so Performance Insights and pg_stat_activity are the better tools for that view — no worker-side scrape needed. Keeps the pg_pool_max_connections probe via duckdb_settings(), which works, and the per-query postgres_scan_seconds histogram and postgres_scan_ms query_log column from #598.
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Summary
Follow-up cleanup after #598. The
postgres_query()-basedpg_stat_activityscrape silently no-ops in our DuckDB build, leavingduckgres_ducklake_metadata_connectionsempty in dev and never reporting any data. Dead code is worse than no code here: it gives the misleading impression that "no data" means "no connections", instead of "this never worked".Removed:
scrapeMetadataConnectionsByStateand itspostgres_querycall induckdbservice/service.goMetadataConnectionsByStategauge inserver/observe/metrics.goKept (works, confirmed wired):
duckgres_ducklake_metadata_pool_max_connectionsgauge — scraped viaduckdb_settings(), which is universally available.duckgres_postgres_scan_seconds{org}histogram andduckdb.postgres_scan_thread_sspan attribute (per-query metadata DB time).system.query_log.postgres_scan_mscolumn —QueryLoggeris a real, wired feature (configstore singleton incontrolplane/configstore/models.go:287, CLI flag, admin API, plumbed throughcmd/duckgres-worker/main.go:214); the column just sits idle in deployments whereQueryLog.Enabled=falseand lights up automatically when the feature is flipped on.application_name=duckgres/<org-id>injection — Aurora-sidepg_stat_activity/ Performance Insights are the better tool for live connection state anyway.Test plan
go build ./...go vet ./...go test ./duckdbservice/ ./server/observe/