Re: PostgreSQL as a local in-memory cache

Bruce Momjian wrote:
> Tom Lane wrote:
> > Dimitri Fontaine <dfontaine@hi-media.com> writes:
> > > Josh Berkus <josh@agliodbs.com> writes:
> > >> a) Eliminate WAL logging entirely
> > >> b) Eliminate checkpointing
> > >> c) Turn off the background writer
> > >> d) Have PostgreSQL refuse to restart after a crash and instead call an
> > >> exteral script (for reprovisioning)
> >
> > > Well I guess I'd prefer a per-transaction setting, allowing to bypass
> > > WAL logging and checkpointing.
> >
> > Not going to happen; this is all or nothing.
> >
> > > Forcing the backend to care itself for
> > > writing the data I'm not sure is a good thing, but if you say so.
> >
> > Yeah, I think proposal (c) is likely to be a net loss.
> >
> > (a) and (d) are probably simple, if by "reprovisioning" you mean
> > "rm -rf $PGDATA; initdb".  Point (b) will be a bit trickier because
> > there are various housekeeping activities tied into checkpoints.
> > I think you can't actually remove checkpoints altogether, just
> > skip the flush-dirty-pages part.
>
> Based on this thread, I have developed the following documentation patch
> that outlines the performance enhancements possible if durability is not
> required.  The patch also documents that synchronous_commit = false has
> potential committed transaction loss from a database crash (as well as
> an OS crash).

Applied.

--
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + None of us is going to be here forever. +