On 11/14/2012 10:08 AM, Bruce Momjian wrote:
On Wed, Nov 14, 2012 at 06:11:27AM +0200, Ants Aasma wrote:
I agree that parallel restore for schemas is a hard problem. But I
didn't mean parallelism within the restore, I meant that we could
start both postmasters and pipe the output from dump directly to
restore. This way the times for dumping and restoring can overlap.
Wow, that is a very creative idea. The current code doesn't do that,
but this has the potential of doubling pg_upgrade's speed, without
adding a lot of complexity. Here are the challenges of this approach:
* I would need to log the output of pg_dumpall as it is passed to psql
so users can debug problems
Instead of piping it directly, have pg_upgrade work as a tee, pumping
bytes both to psql and a file. This doesn't seem terribly hard.
* pg_upgrade never runs the old and new clusters at the same time for
fear that it will run out of resources, e.g. shared memory, or if they
are using the same port number. We can make this optional and force
different port numbers.
Right.
cheers
andrew
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