feat: Skip writeback for chunks fetched by queriers older than a duration #15393
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pkg/storage/chunk/fetcher/fetcher.go
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| @@ -138,6 +140,10 @@ func (c *Fetcher) FetchChunks(ctx context.Context, chunks []chunk.Chunk) ([]chun | |||
| l2OnlyChunks := make([]chunk.Chunk, 0, len(chunks)) | |||
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| for _, m := range chunks { | |||
| if c.skipQueryWritebackCacheOlderThan > 0 && m.From.Time().Before(time.Now().UTC().Add(-c.skipQueryWritebackCacheOlderThan)) { | |||
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this does not look like the right place for this check. It is preventing the fetcher from fetching chunks older than skipQueryWritebackCacheOlderThan.
WriteBackCache() method might be a better place to add this
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Thank you for catching that and I do have the check in the WriteBackCache.
What I do want to add is the ability to short circuit a cache lookup if it before this duration value. There might already be a setting for that and need to take a deeper look
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What this PR does / why we need it:
This change will prevent any chunks fetched by the querier to not be written back to the chunk cache that are before a given time range.
95% of the searches that our engineering teams execute are within a 7 day range and we have a cache enabled to support 14 days worth of chunks to aid in query performance. We recently found that we have compliance need to maintain searchable logs for 365 days. While these queries outside of the 7 day window are rare, they tend to be longer duration searches of up to 30 days for compliance, contain a lot of data, and tend to be one-off searches.
Currently these chunks fetched by queriers outside our target window are written back to the chunk cache and causing more recent data to be evicted from the cache and impacting the query performance for the most recent data.
Which issue(s) this PR fixes:
Fixes #14983
Special notes for your reviewer:
Checklist
CONTRIBUTING.mdguide (required)featPRs are unlikely to be accepted unless a case can be made for the feature actually being a bug fix to existing behavior.docs/sources/setup/upgrade/_index.mddeprecated-config.yamlanddeleted-config.yamlfiles respectively in thetools/deprecated-config-checkerdirectory. Example PR