Re: pglz performance - Mailing list pgsql-hackers

From Andrey Borodin
Subject Re: pglz performance
Date
Msg-id 3C62CD88-AEAC-4041-9BF3-ACCE70C3A5F8@yandex-team.ru
Whole thread Raw
In response to Re: pglz performance  (Peter Eisentraut <peter.eisentraut@2ndquadrant.com>)
Responses Re: pglz performance
List pgsql-hackers
Oleg, Peter, thanks for looking into this!

I hope to benchmark decompression on Silesian corpus soon.

PFA v2 with better comments.

> 27 сент. 2019 г., в 14:41, Peter Eisentraut <peter.eisentraut@2ndquadrant.com> написал(а):
>
> After reviewing this thread and more testing, I think
> 0001-Use-memcpy-in-pglz-decompression.patch appears to be a solid win
> and we should move ahead with it.
>
> I don't, however, fully understand the code changes, and I think this
> could use more and better comments.  In particular, I wonder about
>
> off *= 2;
I've changed this to
off += off;

>
> This is new logic that isn't explained anywhere.
>
> This whole function is commented a bit strangely.  It begins with
> "Otherwise", but there is nothing before it.  And what does "from OUTPUT
> to OUTPUT" mean?  There is no "output" variable.  We should make this
> match the code better.


I've added small example to illustrate what is going on.

Thanks!

--
Andrey Borodin
Open source RDBMS development team leader
Yandex.Cloud

Attachment

pgsql-hackers by date:

Previous
From: Antonin Houska
Date:
Subject: Re: Attempt to consolidate reading of XLOG page
Next
From: Amit Kapila
Date:
Subject: Re: PATCH: logical_work_mem and logical streaming of largein-progress transactions