Allow drop slots when it gets deleted from the manifest #2089
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FxKu
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Nov 2, 2022
hughcapet
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Nov 16, 2022
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FxKu
reviewed
Dec 16, 2022
| @@ -625,7 +625,7 @@ func (c *Cluster) checkAndSetGlobalPostgreSQLConfiguration(pod *v1.Pod, effectiv | |||
| } | |||
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| // check if there exist only config updates that require a restart of the primary | |||
| if !util.SliceContains(restartPrimary, false) && len(configToSet) == 0 { | |||
| if len(restartPrimary) > 0 && !util.SliceContains(restartPrimary, false) && len(configToSet) == 0 { | |||
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if there's nothing to set requiresMasterRestart would become true here which is wrong
FxKu
reviewed
Dec 28, 2022
e2e/tests/test_e2e.py
Outdated
| SELECT slot_name | ||
| FROM pg_replication_slots | ||
| WHERE slot_name = '%s'; | ||
| """ % (slot_to_remove) |
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can the slot query not be defined once so we do formatting inside the assertions (self.eventuallyEqual)
FxKu
reviewed
Dec 28, 2022
FxKu
reviewed
Dec 28, 2022
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Problem
Users can specify replication slots in the Postgres manifest and they are added to the database via Patroni REST API. When the slot is removed from the manifest, it won't get deleted in the database. Here we follow the convention of the operator never dropping database objects because manifest edits could have been wrong accidentally.
However, with logical replication slots the situation is a little different. If they are not used, diskspace will grow until it's exhausted. Our users are mostly not aware of this and think the slot will be gone when it's not desired anymore in the manifest. Some users check the database and still find the slot. So they call
pg_drop_replication_slotfunction to drop it only to be surprised seconds later that the slot is recreated.Solution
The operator should drop replication slots when they are removed from the manifest by updating the Patroni config. So far, our code only adds new slots or slots that differ from existing slots to the configToSet. Patroni's config endpoint only merges the patches - it does not override the slots section.
To drop the replication slots that get deleted from the manifest, we can set the unused slots to null in the current Patroni's configuration and using
PATCH /config.