What did you do?
I'm running postgres_exporter in multi-target mode and target a pg 12.17 cluster

What did you expect to see?
No issues

What did you see instead? Under which circumstances?
I got the following error mesage:

{"time":"2024-11-27T16:42:03.793572559Z","level":"ERROR","source":"collector.go:201","msg":"collector failed","target":"<server>:5431/db","name":"replication_slot","duration_seconds":0.028229965,"err":"pq: column \"safe_wal_size\" does not exist"}

This column exists starting pg13 so the exporter is likely missing a version check

Environment

• postgres_exporter version:

postgres_exporter, version 0.16.0 (branch: HEAD, revision: a324fe37bca5193a293118b940b3df7ab3a8505c) build user: root@buildkitsandbox build date: 20241127-14:34:19 go version: go1.23.0 platform: linux/amd64 tags: unknown 

• postgres_exporter flags:

 --config.file=/app/postgres_exporter.yml --log.format=json --collector.postmaster --collector.index --collector.stat_user_indexes --collector.stat_checkpointer 

• PostgreSQL version:

  12.17

I'll try to provide a PR for that