Re: Postgres as In-Memory Database?

Em 17/11/2013 12:15, rob stone escreveu:
>
> On Sun, 2013-11-17 at 12:25 +0100, Stefan Keller wrote:
>> How can Postgres be used and configured as an In-Memory Database?
>>
>>
>> Does anybody know of thoughts or presentations about this "NoSQL
>> feature" - beyond e.g. "Perspectives on NoSQL" from Gavin Roy at PGCon
>> 2010)?
>>
>>
>> Given, say 128 GB memory or more, and (read-mostly) data that fit's
>> into this, what are the hints to optimize Postgres (postgresql.conf
>> etc.)?
>>
>>
>> -- Stefan
> Not as being completely "in memory".
> Back in the "good ol'days" of DMS II (written in Algol and ran on
> Burroughs mainframes) and Linc II (also Burroughs) it was possible to
> define certain tables as being memory resident. This was useful for low
> volatile data such as salutations, street types, county or state codes,
> time zones, preferred languages, etc.
> It saved disk I/O twice. Firstly building your drop down lists and
> secondly when the entered data hit the server and was validated.
> It would be good to have a similar feature in PostgreSql.
> If a table was altered by, say inserting a new street type, then the
> data base engine has to refresh the cache. This is the only overhead.
>
> Cheers,
> Robert

For this purpose (building drop down lists, salutations, street types,
county or state codes), I keep a permanent data cache at app server side
(after all, they will be shared among all users - even on a multi tenant
application). This avoids network connection, and keep database server
memory available for database operations (like reporting and transactions).
But I agree there are lots of gaings having a "in memory" option for
tables and so. I believe PostgreSQL already does that automatically
(most used tables are kept in memory cache).

Edson.