Re: Performance of the temporary table creation and use.

Tom Lane escreveu:

>Luiz Gonzaga da Mata <gonzaga@pbh.gov.br> writes:
>  
>
>> Although to have changed they sort_mem/work_mem it for 1 MB, it did not 
>>use this area in available memory for the connection to make the 
>>creation of the temporary table.
>>    
>>
>
>Why would you expect it to, and why would you think there is any
>advantage?  A small, short-lived temp table will probably never actually
>be spilled to disk by the kernel (we never fsync them) so the actual
>performance improvement would be minimal.
>
>  
>
It can be that kernel not writing physically in disk, but can be also 
that write.

If the use to order by, distinct, creating  index  and other temporary 
resources  is to greater then it sort_mem/work_mem per processes, the 
creating resource in disk can be used.

If to create a concept of work_mem_pool internally, we could optimize 
the resources of SO X SGDB and and the use most rational of resource..

For the administrator of the operational system and the administrator of 
the SGDB that is very important.

Work_mem_pool = (number of connections->postgresql.conf) X 
(work_mem->postgresql.conf).

If *memory real used* for all the user processes will be minor who 
work_mem_pool, would use more resources in memory of that simply the 
value of work_mem individual.

The general behavior of the PostgreSQL would be very better.

regards,

Luiz  Gonzaga da Mata