Re: PostgreSQL as a local in-memory cache

From: Bruce Momjian
Subject: Re: PostgreSQL as a local in-memory cache
Date: ,
Msg-id: 201006282157.o5SLvQ922390@momjian.us
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In response to: Re: PostgreSQL as a local in-memory cache  (Bruce Momjian)
Responses: Re: PostgreSQL as a local in-memory cache  (Robert Haas)
List: pgsql-performance

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PostgreSQL as a local in-memory cache  ("", )
 Re: PostgreSQL as a local in-memory cache  ("", )
  Re: PostgreSQL as a local in-memory cache  (Josh Berkus, )
   Re: PostgreSQL as a local in-memory cache  ("Pierre C", )
   Re: PostgreSQL as a local in-memory cache  (Dimitri Fontaine, )
    Re: PostgreSQL as a local in-memory cache  (Tom Lane, )
     Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
      Re: PostgreSQL as a local in-memory cache  (Pavel Stehule, )
       Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
      Re: PostgreSQL as a local in-memory cache  (Robert Haas, )
       Re: PostgreSQL as a local in-memory cache  (Dave Page, )
        Re: PostgreSQL as a local in-memory cache  (Tom Lane, )
         Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
         Re: PostgreSQL as a local in-memory cache  (Dimitri Fontaine, )
       Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
     Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
      Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
       Re: PostgreSQL as a local in-memory cache  (Robert Haas, )
        Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
         Re: PostgreSQL as a local in-memory cache  ("Kevin Grittner", )
         Re: PostgreSQL as a local in-memory cache  (Robert Haas, )
          Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
           Re: PostgreSQL as a local in-memory cache  (Tom Lane, )
            Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
             Re: PostgreSQL as a local in-memory cache  (Jignesh Shah, )
              Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
               Re: PostgreSQL as a local in-memory cache  (Brad Nicholson, )
                Re: PostgreSQL as a local in-memory cache  (Bruce Momjian, )
               Re: PostgreSQL as a local in-memory cache  (Jignesh Shah, )
                Re: PostgreSQL as a local in-memory cache  (Greg Smith, )
    Re: PostgreSQL as a local in-memory cache  ("Pierre C", )
     Re: PostgreSQL as a local in-memory cache  (Matthew Wakeling, )
      Re: PostgreSQL as a local in-memory cache  ("Pierre C", )
       Re: PostgreSQL as a local in-memory cache  (Josh Berkus, )
        Re: PostgreSQL as a local in-memory cache  (Rob Wultsch, )
         Re: PostgreSQL as a local in-memory cache  (Robert Haas, )
          Re: PostgreSQL as a local in-memory cache  (Josh Berkus, )
           Re: PostgreSQL as a local in-memory cache  (Pavel Stehule, )
            Re: PostgreSQL as a local in-memory cache  ("Joshua D. Drake", )
             Re: PostgreSQL as a local in-memory cache  (Pavel Stehule, )
              Re: PostgreSQL as a local in-memory cache  ("A.M.", )
               Re: PostgreSQL as a local in-memory cache  (Pavel Stehule, )
            Re: PostgreSQL as a local in-memory cache  (Josh Berkus, )
             Re: PostgreSQL as a local in-memory cache  (Pavel Stehule, )
            Re: PostgreSQL as a local in-memory cache  ("Joshua D. Drake", )
      Re: PostgreSQL as a local in-memory cache  (Josh Berkus, )
    Re: PostgreSQL as a local in-memory cache  (Josh Berkus, )
     Re: PostgreSQL as a local in-memory cache  (Tom Lane, )
   Re: PostgreSQL as a local in-memory cache  (Greg Smith, )
   Re: PostgreSQL as a local in-memory cache  (Robert Haas, )
 Re: PostgreSQL as a local in-memory cache  (Dave Crooke, )
  Re: PostgreSQL as a local in-memory cache  (Craig James, )

Bruce Momjian wrote:
> Tom Lane wrote:
> > Dimitri Fontaine <> writes:
> > > Josh Berkus <> 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  <>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

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


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From: Bruce Momjian
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Subject: Re: PostgreSQL as a local in-memory cache