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Re: PostgreSQL as a local in-memory cache - Mailing list pgsql-performance

From Bruce Momjian
Subject Re: PostgreSQL as a local in-memory cache
Date
Msg-id 201006291332.o5TDWTZ01574@momjian.us
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In response to Re: PostgreSQL as a local in-memory cache  (Robert Haas <robertmhaas@gmail.com>)
Responses Re: PostgreSQL as a local in-memory cache  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
Re: PostgreSQL as a local in-memory cache  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-performance
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Robert Haas wrote:
> On Mon, Jun 28, 2010 at 5:57 PM, Bruce Momjian <bruce@momjian.us> wrote:
> >> The patch also documents that synchronous_commit = false has
> >> potential committed transaction loss from a database crash (as well as
> >> an OS crash).
>
> Is this actually true?

I asked on IRC and was told it is true, and looking at the C code it
looks true.  What synchronous_commit = false does is to delay writing
the wal buffers to disk and fsyncing them, not just fsync, which is
where the commit loss due to db process crash comes from.

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

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

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