Re: PG as in-memory db? How to warm up and re-populate buffers? How to read in all tuples into memory?

From: Stefan Keller <sfkeller(at)gmail(dot)com>
To: cedric(at)2ndquadrant(dot)fr
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: PG as in-memory db? How to warm up and re-populate buffers? How to read in all tuples into memory?
Date: 2012-02-26 20:56:35
Message-ID: CAFcOn28CvP96hUa9QL75E56wUqVB_oDbGFHOLeiXqVNHPUkhtg@mail.gmail.com
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Hi,

2012/2/26 Cédric Villemain <cedric(at)2ndquadrant(dot)fr> wrote:
>> 1. How can I warm up or re-populate shared buffers of Postgres?
>
> There was a patch proposed for postgresql which purpose was to

Which patch are you referring to?

> snapshot/Restore postgresql buffers, but it is still not sure how far that
> really help to have that part loaded.

What's not sure and why?

>> 2. Are there any hints on how to tell Postgres to read in all table
>> contents into memory?
>
> I wrote pgfincore for the OS part: you can use it to preload table/index in OS
> cache, and do snapshot/restore if you want fine grain control of what part of
> the object you want to warm.
> https://github.com/klando/pgfincore

Yes, now I remember. I have a look at that.

I'd still like to see something where PG really preloads tuples and
treats them "always in-memory" (given they fit into RAM).
Since I have a "read-only" database there's no WAL and locking needed.
But as soon as we allow writes I realize that the in-memory feature
needs to be coupled with other enhancements like replication (which
somehow would avoid WAL).

Yours, Stefan

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