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https://issues.apache.org/jira/browse/JAMES-3679?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Benoit Tellier closed JAMES-3679.
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    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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