Add pg_synchronized_standby_slots_invalid metric#19
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`synchronized_standby_slots` must be a subset of replication slots. However, it's possible to configure postgres so that is not true. This breaks replication, but worse than that, any queries that use parallel background workers will fail to execute. Add a `pg_synchronized_standby_slots_invalid` metric that is `0` when no slots are invalid, and then the metric size is the number of invalid slots to track and detect this. Does not include slot name as label/etc as this could cause unbounded series growth.
tom-pang
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frouioui
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Feb 16, 2026
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| synchronizedStandbySlotsQuery = ` | ||
| SELECT count(*) AS invalid_count |
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I would also include the name of the offending slot(s), so that we can add it as a label, easier debugging.
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think we can just include a query in the runbook I think, don't wanna cause metric explosion here.
frouioui
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Feb 16, 2026
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pg_synchronized_standby_slots_invalidgauge metric — counts slots listed in the PG17synchronized_standby_slotsGUC that don't exist as physical replication slotspg_is_in_recovery())Testing
Unit tests cover these cases