From: | "Greg Sabino Mullane" <greg(at)turnstep(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Justifying a PG over MySQL approach to a project |
Date: | 2009-12-18 02:47:18 |
Message-ID: | 03093701f213760ac39ad619dba958fa@biglumber.com |
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Lists: | pgsql-general |
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> One concern I have about these trigger based replication systems is
> that I fear it may ping the slave for each and every DML statement
> separately in time and in a transaction. My slave will literally be
> 1400 miles away and all replication communications will be over the
> net. If I have a transaction which has 1000 DML statements in it, is
> this thing going to update the slave 1000 times separately over the
> net ? (I may not live long enough to see it finish) Or will it be
> smart enough to wait until I "commit" then send over a single bundle
> of 1000 DML? The time diff will be more than significant.
Both Slony and Bucardo are transaction based, meaning all 1000 changes
will happen at once, and only when the transaction has committed. In
practice, you'll find that both are surprisingly quick.
With Bucardo, the number of changes may be much less than 1000, as it
is data based, not statement based. Thus, as an extreme example, if
the 1000 statements are all updating a single row, only a single
update (actually a delete/insert) is done on the slave.
- --
Greg Sabino Mullane greg(at)turnstep(dot)com
End Point Corporation http://www.endpoint.com/
PGP Key: 0x14964AC8 200912172144
http://biglumber.com/x/web?pk=2529DF6AB8F79407E94445B4BC9B906714964AC8
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