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Posted to server-dev@james.apache.org by "Benoit Tellier (Jira)" <se...@james.apache.org> on 2022/01/09 12:21:00 UTC
[jira] [Closed] (JAMES-3679) Solve tombstones warning for mailbox recent table
[ https://issues.apache.org/jira/browse/JAMES-3679?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Benoit Tellier closed JAMES-3679.
---------------------------------
Resolution: Fixed
> Solve tombstones warning for mailbox recent table
> -------------------------------------------------
>
> Key: JAMES-3679
> URL: https://issues.apache.org/jira/browse/JAMES-3679
> Project: James Server
> Issue Type: Improvement
> Components: mailbox
> Reporter: Benoit Tellier
> Priority: Major
> Fix For: 3.7.0
>
> Time Spent: 20m
> Remaining Estimate: 0h
>
> We noticed tombstone warnings on some tables namely firstunseen, mailboxrecent and (less) messageidtable.
> mailbox recent table is used to keep track of recent emails within a mailbox in order to fasten SELECT (and avoid full reads of messageidtable). The behaviour is to generally to clean up entries straight after reading them.
> Hence we only have a few recent emails, but keep tumbstones for 10 days, hence selets often have to cross many tumbstone.
> However this property is interesting: if we can afford some false positives, then we could aggressively decrease gc_grace_period to 0. This would cause tumbstones to be disposed of at the first compaction, significantly reducing their impact. The downside is that mis-synchronisation might lead to entries re-appearing once deleted. Which is likely acceptable on some rare occasion for mailbox recent. And such entries would eventually be cleaned up (as recent entries are removed on SELECT)
> We experimented gc_grace_period = 0 on one of our production plateform and no longer see warnings for mailboxrecent table hance wanted to share this here.
> Yet this approach can not be applied for other tables (firstunseen / messageidtable)
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