Re: [HACKERS] GSoC 2017: weekly progress reports (week 6) - Mailing list pgsql-hackers

From Teodor Sigaev
Subject Re: [HACKERS] GSoC 2017: weekly progress reports (week 6)
Date
Msg-id a3a6f770-8834-70a3-9a59-1a9ad810426c@sigaev.ru
Whole thread Raw
In response to Re: [HACKERS] GSoC 2017: weekly progress reports (week 6)  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
Responses Re: [HACKERS] GSoC 2017: weekly progress reports (week 6)  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
List pgsql-hackers

Alvaro Herrera wrote:
> I don't quite understand the new call in gininsert -- I mean I see that
> it wants to check for conflicts even when fastupdate is set, but why?
If fastupdate is set then we check conflict with whole index, not a particular 
pages in it. Predicate lock on penging list pages will be effectively a lock 
over index, because every scan will begin from pending list and each insert will 
insert into it. I

> Maybe, just maybe, it would be better to add a new flag to the
> GinCheckForSerializableConflictIn function, that's passed differently
> for this one callsite, and then a comment next to it that indicates why
> do we test for fastupdates in one case and not the other case.
> If you don't like this idea, then I think more commentary on why
> fastupdate is not considered in gininsert is warranted.
> 
> In startScanEntry, if you "goto restartScanEntry" in the fastupdate
> case, are you trying to acquire the same lock again?  Maybe the lock
> acquire should occur before the goto target? (If this doesn't matter for
> some reason, maybe add a comment about it)
Thank you for noticing that, I've completely rework this part. Somehow I 
misreaded actual work of GinGetPendingListCleanupSize() :(.

See attached patch
-- 
Teodor Sigaev                                   E-mail: teodor@sigaev.ru
                                                    WWW: http://www.sigaev.ru/

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