On Aug 21, 2006, at 15:00 , D'Arcy J.M. Cain wrote:

On Mon, 21 Aug 2006 14:46:05 -0400
"Gregory Maxwell" <[EMAIL PROTECTED]> wrote:
On 8/21/06, Alvaro Herrera <[EMAIL PROTECTED]> wrote:
But the confirmation that needs to come is that the WAL changes have
been applied (fsync'ed), so the performance will be terrible. So bad, that I don't think anyone will want to use such a replication system ...

Okay. I give up... Why is waiting for fsync on a fast local network
which takes 15us to send a message (infiniband is cheap..) an
unimaginable delay when we tolerate a local 8ms fsync delay on systems
without writeback cache?

OK, that solves your problem.  How about my problem where replication
has to happen on servers in three countries on two continents and
thousands of updates a second have to happen in less that 10ms? This is
the critical issue with replication - one size does not fit all.
Syncronous replication, in particular, fits almost no one.

My experience is that any replication needs to be based on your business
rules which will vary widely.

Sure- and more specifically, replication rules may differ on every table according to those rules. The current solutions are on/off for a list of tables. I wonder if the various pgsql replication engines have any problems co-existing...


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