From: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
---|---|
To: | Andres Freund <andres(at)anarazel(dot)de> |
Cc: | James Coleman <jtc331(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: [DOC] Document concurrent index builds waiting on each other |
Date: | 2020-03-25 20:12:48 |
Message-ID: | 20200325201248.GA11538@alvherre.pgsql |
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Lists: | pgsql-hackers |
On 2020-Mar-25, Andres Freund wrote:
> > I don't know if my approach is exactly what Andres has in mind
>
> Not quite. I don't think it's generally correct for CIC to set
> PROC_IN_VACUUM. I'm doubtful it's the case even just for plain indexes -
> we don't want rows to be pruned away from under us. I also think we'd
> want to set such a flag during all of the CIC phases?
>
> What I was thinking of was a new flag, with a distinct value from
> PROC_IN_VACUUM. It'd currently just be specified in the
> GetCurrentVirtualXIDs() calls in WaitForOlderSnapshots(). That'd avoid
> needing to wait for other CICs on different relations. Since CIC is not
> permitted on system tables, and CIC doesn't do DML on normal tables, it
> seems fairly obviously correct to exclude other CICs.
Hmm, that sounds more promising.
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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