Re: Possible Commit Syntax Change for Improved TPS - Mailing list pgsql-hackers

From Christopher Browne
Subject Re: Possible Commit Syntax Change for Improved TPS
Date
Msg-id m34qyuqy3g.fsf@wolfe.cbbrowne.com
Whole thread Raw
Responses Re: Possible Commit Syntax Change for Improved TPS  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
In the last exciting episode, seunosewa@inaira.com (Seun Osewa) wrote:
> So I want to ask, "what is databases have a 'COMMIT NOSYNC;' option?" 
> Then we can really improve "transaction-per-second" performance for a
> database that has lots of non-critical transactions while not
> jeopardising the durability of critical transactions in the
> (relatively unlikely) case of system failure.  Primarily through
> combining the log updates for several non-critical transactions.

Another possibility in this would be to have not one, but TWO
backends.  

One database, on one port, is running in FSYNC mode, so that the
"really vital" stuff is sure to get committed quickly.  The other, on
another port, has FSYNC turned off in its postgresql.conf file, and
the set of "untrusted" files go there.

That has the added merit that you can do other tuning that
distinguishes between the "important" and "unimportant" data.  For
instance, if the "unimportant" stuff is a set of logs that don't get
directly referred to, you might set cacheing real low on that backend
so that cache isn't being wasted on unimportant data.

So if you really want this, you can have it right now without anyone
doing any implementation work.
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