Re: Load Distributed Checkpoints, revised patch

Heikki Linnakangas wrote:

> - The signaling between RequestCheckpoint and bgwriter is a bit tricky.
> Bgwriter now needs to deal immediate checkpoint requests, like those
> coming from explicit CHECKPOINT or CREATE DATABASE commands, differently
> from those triggered by checkpoint_segments. I'm afraid there might be
> race conditions when a CHECKPOINT is issued at the same instant as
> checkpoint_segments triggers one. What might happen then is that the
> checkpoint is performed lazily, spreading the writes, and the CHECKPOINT
> command has to wait for that to finish which might take a long time. I
> have not been able to convince myself neither that the race condition
> exists or that it doesn't.

Isn't it just a matter of having a flag to tell whether the checkpoint
should be quick or spread out, and have a command set the flag if a
checkpoint is already running?

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Alvaro Herrera http://www.CommandPrompt.com/
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