[+] allow sink schema upgrades without --metrics/--sources, fixes #1114

[pashagolub]

Removed the requirement that both sources and metrics must be PostgreSQL connections. Added support for upgrading only sink when sources/metrics are YAML files. Changed error messages to warnings ([WARN]) for non-upgradeable configurations. Only fails if no components support upgrade (previously failed if any didn't support upgrade).

[coveralls]

Pull Request Test Coverage Report for Build 21673980335

Details

• 47 of 72 (65.28%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.008%) to 76.14%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
internal/db/conn.go	0	4	0.0%
internal/sinks/postgres.go	0	21	0.0%

Totals
Change from base Build 21667726737:	0.008%
Covered Lines:	4126
Relevant Lines:	5419

---

💛 - Coveralls

[0xgouda]

Also, when upgrading from v4.1 to v5, now the CLI states that we should run config upgrade, which succeeds, but without changing the admin schema. Maybe we should add a new sink migration for changing the functions that got updates in the admin schema?

$ go run ./cmd/pgwatch --sources="contrib/sample.sources.yaml" --sink="postgres://postgres:postgres@localhost:5437/postgres" --metrics="internal/metrics/metrics.yaml" 
2026-02-04 02:43:30.882 [INFO] [sink:postgres] [db:postgres] initialising measurements database...
2026-02-04 02:43:30.891 [INFO] [sink:postgres] [db:postgres] measurements sink is activated
2026-02-04 02:43:30.891 [ERROR] sink database schema is outdated, please run migrations using `pgwatch config upgrade` command
exit status 1

$ go run ./cmd/pgwatch --sources="contrib/sample.sources.yaml" --sink="postgres://postgres:postgres@localhost:5437/postgres" --metrics="internal/metrics/metrics.yaml" config upgrade
[WARN] configuration storage does not support upgrade, skipping
2026-02-04 02:43:35.098 [INFO] [sink:postgres] [db:postgres] initialising measurements database...
2026-02-04 02:43:35.107 [INFO] [sink:postgres] [db:postgres] measurements sink is activated
2026-02-04 02:43:35.117 [INFO] [sink:postgres] [db:postgres] Applying migration named '01110 Apply postgres sink schema migrations'...
2026-02-04 02:43:35.118 [INFO] [sink:postgres] [db:postgres] Applied migration named '01110 Apply postgres sink schema migrations'

$ go run ./cmd/pgwatch --sources="contrib/sample.sources.yaml" --sink="postgres://postgres:postgres@localhost:5437/postgres" --metrics="internal/metrics/metrics.yaml"               
2026-02-04 02:43:39.332 [INFO] [sink:postgres] [db:postgres] initialising measurements database...
2026-02-04 02:43:39.341 [INFO] [sink:postgres] [db:postgres] measurements sink is activated
2026-02-04 02:43:39.342 [INFO] [sources:1] sources refreshed
2026-02-04 02:43:39.346 [INFO] [metrics:74] [presets:14] metrics and presets refreshed
2026-02-04 02:43:39.352 [INFO] [source:omdb.test] [recovery:false] Connect OK. Version: PostgreSQL 18.1 (Ubuntu 18.1-1.pgdg24.04+2) on x86_64-pc-linux-gnu, compiled by gcc (Ubuntu 13.3.0-6ubuntu2~24.04) 13.3.0, 64-bit
2026-02-04 02:43:39.352 [INFO] [source:omdb.test] [metric:wal] [interval:60] starting gatherer
2026-02-04 02:43:39.353 [INFO] [source:omdb.test] [metric:wal] [rows:1] [cache:false] measurements fetched
2026-02-04 02:43:40.296 [ERROR] [sink:postgres] [db:postgres] [sql:select * from admin.ensure_partition_metric_dbname_time($1, $2, $3, $4)] [args:[wal omdb.test 2026-02-04 02:43:39.353655 +0200 EET 1 week]] [err:ERROR: cross-database references are not implemented: "subpartitions.wal_omdb.test" (SQLSTATE 0A000)] [pid:46954] [time:4.732447ms] Query

[pashagolub]

Also, when upgrading from v4.1 to v5, now the CLI states that we should run config upgrade, which succeeds, but without changing the admin schema. Maybe we should add a new sink migration for changing the functions that got updates in the admin schema?

I thought they were added already... Would you please add those in a separate PR to mention the fact of migration. thanks