Re: Fractions in GUC variables

Added to TODO:
       o Consider normalizing fractions in postgresql.conf, perhaps         using '%'
         http://archives.postgresql.org/pgsql-hackers/2007-06/msg00550.php


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Heikki Linnakangas wrote:
> We have these GUC variables that define a fraction of something:
> 
> #autovacuum_vacuum_scale_factor = 0.2	# fraction of rel size before
> 					# vacuum
> #autovacuum_analyze_scale_factor = 0.1	# fraction of rel size before
> 					# analyze
> 
> #bgwriter_lru_percent = 1.0		# 0-100% of LRU buffers scanned/round
> #bgwriter_all_percent = 0.333		# 0-100% of all buffers scanned/round
> 
> Autovacuum settings use fractions, and bgwriter settings use a 
> percentage. Fortunately these settings are not related so there's not 
> too much potential for confusion, but it seems we should have a common 
> way to define settings like that.
> 
> A nice way would be that the base unit would be a fraction, like in the 
> autovacuum settings, but you could add a %-sign to give it as a percent, 
> just like you can use KB/MB etc. I'm not sure if we can do anything for 
> those without breaking backwards-compatibility, though.
> 
> Any ideas? The load distributed checkpoints patch adds one more GUC 
> variable like. I'm inclined to follow the example of the bgwriter 
> settings because it's more closely related to them, though I like the 
> autovacuum style more.
> 
> -- 
>    Heikki Linnakangas
>    EnterpriseDB   http://www.enterprisedb.com
> 
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--  Bruce Momjian          http://momjian.us EnterpriseDB                             http://postgres.enterprisedb.com
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