Re: PostgreSQL-related topics of theses and seminary works sought (Was: Hash index use presently(?) discouraged...)

2011/9/19 Vitalii Tymchyshyn <tivv00(at)gmail(dot)com>:
> 17.09.11 23:01, Stefan Keller написав(ла):
>>
>> * more... ?
>
> What I miss from my DB2 UDB days are buffer pools. In PostgreSQL terms this
> would be part of shared buffers dedicated to a relation or a set of
> relations. When you have a big DB (not fitting in memory) you also usually
> want some small tables/indexes be in memory, no matter what other load DB
> has.
> Complimentary features are:
> 1) Relations preloading at startup - ensure this relation are in memory.

you can use pgfincore extension to achieve that, for the OS cache. It
does not look interesting to do that for shared_buffers of postgresql
(the subject has been discussed and can be discussed again, please
check mailling list archieve first)

> 2) Per buffer pool (or relation) page costs - tell it that this
> indexes/tables ARE in memory

you can use tablespace parameters (*_cost) for that, it has been
rejected for tables in the past.
I did propose something to start to work in this direction.
See "[WIP] cache estimates, cache access cost" in postgresql-hackers
mailling list.

This proposal let inform the planner of the table memory usage and
take that into account.

>
> Best regards, Vitalii Tymchyshyn.
>
> --
> Sent via pgsql-performance mailing list (pgsql-performance(at)postgresql(dot)org)
> To make changes to your subscription:
> http://www.postgresql.org/mailpref/pgsql-performance
>

--
Cédric Villemain +33 (0)6 20 30 22 52
http://2ndQuadrant.fr/
PostgreSQL: Support 24x7 - Développement, Expertise et Formation