Re: [HACKERS] GSoC 2017 : Patch for predicate locking in Gist index

27 марта 2018 г., в 13:45, Alexander Korotkov <a.korotkov@postgrespro.ru> написал(а):

On Tue, Mar 27, 2018 at 11:16 AM, Andrey Borodin <x4mmm@yandex-team.ru> wrote:

> 27 марта 2018 г., в 12:53, Teodor Sigaev <teodor@sigaev.ru> написал(а):
>
> I have a question: why do not CheckForSerializableConflictIn() move  into begining of gistplacetopage()? Seems, it is the single function which actually changes page and all predicate locking stuff will be placed in single function...

gistplacetopage() is called from
1. Buffered build - probably harmless

Yes, harmless, but useless.

 

2. Finish split - i'm not sure about this. It seems to me that it is necessary... then your version is correct.

Yes, it's necessary, because GiST scan can end up on non-leaf page.  So, scan and modify of same non-leaf page should conflict.

Checking for serializable conflicts from buffering build seems useless overhead.  gistplacetopage()

is called from only two places: gistinserttuples() and gistbufferinginserttuples().  In order to evade

useless overhead for buffering build, I've moved CheckForSerializableConflictIn() into gistinserttuples().

+1

Also, both gistdoinsert() and gistplacetopage() are mind blowing in complexity. gistinserttuples() looks like a cosy place if we need to add some more.

Best regards, Andrey Borodin.