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https://issues.apache.org/jira/browse/IMPALA-12491?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Quanlong Huang updated IMPALA-12491:
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Attachment: impala_data_cache.png
> Document whether the remote data cache has TTL
> ----------------------------------------------
>
> Key: IMPALA-12491
> URL: https://issues.apache.org/jira/browse/IMPALA-12491
> Project: IMPALA
> Issue Type: Documentation
> Reporter: Quanlong Huang
> Priority: Major
> Attachments: impala_data_cache.png
>
>
> It's unclear to the users whether the remote data cache has TTL so will
> expire after some time. We have document about the startup flags of remote
> data cache, including the capacity and the eviction policy:
> [https://impala.apache.org/docs/build/html/topics/impala_data_cache.html]
> We should also mention that the cache item won't expire as long as the same
> file metadata is used in the query. The reason is that the cache key is
> (filename, mtime, file offset) where mtime is the last modified time of the
> file. When the mtime in the file metadata doesn't change, the scan request
> could always hit the cache (if capacity is enough).
> CC [~shajini], [~joemcdonnell]
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