Re: Re: GiST optimizing memmoves in gistplacetopage for fixed-size updates [PoC]

Thank you, Alvaro.

Yes, now I see. I'll update gistRedoPageUpdateRecord() to work
accordingly with patched gistplacetopage().
Also, i've noticed that PageAddItem uses MAXALIGN() macro to calculate
tuple size. So, PageIndexTupleOverwrite should behave the same.

About PageIndexDeleteNoCompact() in BRIN. I do not see why
PageIndexDeleteNoCompact() is not a good solution instead of
PageIndexTupleOverwrite? Will it mark tuple as unused until next
PageAddItem will use it's place?

Best regards, Andrey Borodin, Octonica & Ural Federal University.

2016-07-04 22:16 GMT+05:00 Alvaro Herrera <alvherre@2ndquadrant.com>:
> Andrew Borodin wrote:
>> Thank you, Amit.
>>
>> Currently, if WAL reconstruct page in another order it won't be a problem.
>
> We require that replay of WAL leads to identical bytes than the
> original.  Among other things, this enables use of a tool that verifies
> that WAL is working correctly simply by comparing page images.  So
> please fix it instead of just verifying that this works for GiST.
>
> By the way, BRIN indexes have a need of this operation too.  The current
> approach is to call PageIndexDeleteNoCompact followed by PageAddItem.
> I suppose it would be beneficial to use your new routine there too.
>
> --
> Álvaro Herrera                http://www.2ndQuadrant.com/
> PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services