fix: Move redis cache outside of pg transaction #17509
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bretthoerner
approved these changes
Sep 19, 2023
| @@ -631,46 +631,6 @@ describe('DB', () => { | |||
| version: 2, | |||
| }) | |||
| }) | |||
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| describe('with caching', () => { | |||
| it('insertGroup() and updateGroup() update cache', async () => { | |||
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Do you think this test is worth keeping if we changed it to calling upsertGroup, or no?
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I thought about this, but we don't have any tests for that yet and that seems rather low priority given our plans to move to kv store longer term
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Problem
We were doing redis updates within a PG transaction - that's a bad idea. This caused groupidentify events processing to lock up PG and when we got a lot of groupidentify events coming in that would create lag in ingestion.
There isn't really any way to guarantee consistency across the two different data sources, so we might as well do it afterwards outside of the transaction. We run into the same problem with the CH writes anyway too.
more context: https://posthog.slack.com/archives/C0185UNBSJZ/p1695056250917589?thread_ts=1695050984.560789&cid=C0185UNBSJZ
Changes
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How did you test this code?