Re: WAL Rate Limiting

On 17 January 2014 16:30, Heikki Linnakangas <hlinnakangas@vmware.com> wrote:
> It occurs to me that this is very similar to the method I proposed in June
> to enforce a hard limit on WAL usage, to avoid PANIC caused by running out
> of disk space when writing WAL:
>
> http://www.postgresql.org/message-id/51B095FE.6050106@vmware.com
>
> Enforcing a global limit needs more book-keeping than rate limiting
> individual sesssions. But I'm hoping that the CHECK_WAL_BUDGET() calls could
> be used for both purposes.

We can't set a useful hard limit on WAL by default without that being
a bigger foot gun than what we have now.

If we did have a limit, I would look to make it less exact and take it
out of the main path for example by checkpointer - or perhaps only
make the check when we switch xlog files.

So I don't want to include that requirement into this current work.

-- Simon Riggs                   http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services