Re: Speed up Clog Access by increasing CLOG buffers

Andres Freund wrote:

> On 2015-09-07 10:34:10 -0300, Alvaro Herrera wrote:
> > I wonder if it would make sense to explore an idea that has been floated
> > for years now -- to have pg_clog pages be allocated as part of shared
> > buffers rather than have their own separate pool. That way, no separate
> > hardcoded allocation limit is needed. It's probably pretty tricky to
> > implement, though :-(
>
> I still think that'd be a good plan, especially as it'd also let us use
> a lot of related infrastructure. I doubt we could just use the standard
> cache replacement mechanism though - it's not particularly efficient
> either... I also have my doubts that a hash table lookup at every clog
> lookup is going to be ok performancewise.

Yeah. I guess we'd have to mark buffers as unusable for regular pages
("somehow"), and have a separate lookup mechanism. As I said, it is
likely to be tricky.

--
Álvaro Herrera http://www.2ndQuadrant.com/
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