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Thread: Disadvantages on having too many page slots?

Disadvantages on having too many page slots?

From
Francisco Reyes
Date:
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.

Re: Disadvantages on having too many page slots?

From
Csaba Nagy
Date:
> 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.

Re: Disadvantages on having too many page slots?

From
"Joshua D. Drake"
Date:
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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Re: Disadvantages on having too many page slots?

From
Jim Nasby
Date:
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)