Re: Limiting setting of hint bits by read-only queries; vacuum_delay

On 3/24/13 7:14 AM, Simon Riggs wrote:
> Patch to implement is a few hours work. The only complexity is
> deciding how to handle SQL in functions.... to which I would say, as
> simply as possible.

Like the Page replacement ideas, the throttle on how fast something like 
this will get done depends not on development time, but on putting 
together more performance regression tests.  The idea I was thinking 
about is refactoring the background writer's role in hint bit 
maintenance.  If backends could push "this looks dirty" page numbers 
toward the BGW and keep going, it might stream those out to disk under 
its control.

I also have a larger proposal for how to refactor I/O so that both 
queries and CREATE INDEX have similar cost controls to the ones used to 
limit vacuum.  And two more based on collecting extra data for high cost 
queries before they run.

But right now I keep biting my tongue about the design on all these, and 
return to working on one of the patches already in the CF queue instead.

-- 
Greg Smith   2ndQuadrant US    greg@2ndQuadrant.com   Baltimore, MD
PostgreSQL Training, Services, and 24x7 Support www.2ndQuadrant.com