Обсуждение: Disadvantages on having too many page slots?
At one point the databases we had in a machine used 10 million plus page slots. We made the number of page slots 14 million. After a few large system were phased out we now only use about 2 million page slots. Other than hard disk space, are there any disadvantages on having a large number of page slots? DETAIL: A total of 2233472 page slots are in use (including overhead). 2233472 page slots are required to track all free space. Current limits are: 14000000 page slots, 1000 relations, using 82096 KB.
> Other than hard disk space, are there any disadvantages on > having a large number of page slots? It's not using hard disk space, it's using shared memory, so you might want to adjust it to make that memory available for other purposes... > DETAIL: A total of 2233472 page slots are in use (including overhead). > 2233472 page slots are required to track all free space. > Current limits are: 14000000 page slots, 1000 relations, using 82096 KB. I'm not sure how much a difference would make to have ~60M of memory more, but it could mean one more index in memory ;-) Cheers, Csaba.
Francisco Reyes wrote:
> At one point the databases we had in a machine used 10 million plus page
> slots. We made the number of page slots 14 million.
>
> After a few large system were phased out we now only use about 2 million
> page slots. Other than hard disk space, are there any disadvantages on
> having a large number of page slots?
They use shared memory.
>
>
> DETAIL: A total of 2233472 page slots are in use (including overhead).
> 2233472 page slots are required to track all free space.
> Current limits are: 14000000 page slots, 1000 relations, using 82096 KB.
>
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On Apr 18, 2007, at 4:39 PM, Csaba Nagy wrote: >> Other than hard disk space, are there any disadvantages on >> having a large number of page slots? > > It's not using hard disk space, it's using shared memory, so you might > want to adjust it to make that memory available for other purposes... AFAIK, the FSM is written out during a clean shutdown... so from that standpoint it does take disk space. But obviously the memory usage is the only real concern. -- Jim Nasby jim@nasby.net EnterpriseDB http://enterprisedb.com 512.569.9461 (cell)