Re: Questions about guc units

Am Montag, 25. September 2006 04:04 schrieb ITAGAKI Takahiro:
> #shared_buffers = 32000kB # min 128kB or max_connections*16kB
> #temp_buffers = 8000kB # min 800kB
> #effective_cache_size = 8000kB
>
> Are there any reasons to continue to use 1000-unit numbers? Megabyte-unit
> (32MB and 8MB) seems to be more friendly for users. It increases some
> amount of values (4000 vs. 4096), but there is little in it.

The reason with the shared_buffers is that the detection code in initdb has
400kB as minimum value, and it would be pretty complicated to code the
detection code to handle both kB and MB units. If someone wants to try it,
though, please go ahead.

We could probably change the others.

> #max_fsm_pages = 1600000 # min max_fsm_relations*16, 6 bytes each
> #wal_buffers = 8 # min 4, 8kB each
>
> They don't have units now, but should they have GUC_UNIT_BLOCKS and
> GUC_UNIT_XLOG_BLCKSZ unit? I feel inconsistency in them.

max_fsm_pages doesn't have a discernible unit, but wal_buffers probably
should.

--
Peter Eisentraut
http://developer.postgresql.org/~petere/