Re: pg_rewarm status

On Tue, Dec 17, 2013 at 12:35 PM, Jeff Janes <jeff(dot)janes(at)gmail(dot)com> wrote:
> Since it doesn't use directIO, you can't warm the PG buffers without also
> warming FS cache as a side effect. That is why I like 'buffer' as the
> default--if the data fits in shared_buffers, it warm those, otherwise it at
> least warms the FS. If you want to only warm the FS cache, you can use
> either the 'prefetch' or 'read' modes instead.

All right, here is an updated patch. I swapped the second and third
arguments, because I think overriding the prewarm mode will be a lot
more common than overriding the relation fork. I also added defaults,
so you can do this:

SELECT pg_prewarm('pgbench_accounts');

Or this:

SELECT pg_prewarm('pgbench_accounts', 'read');

I also fixed some oversights in the error checks.

I'm not inclined to wait for the next CommitFest to commit this,
because it's a very simple patch and has already had a lot more field
testing than most patches get before they're committed. And it's just
a contrib module, so the damage it can do if there is in fact a bug is
pretty limited. All that having been said, any review is appreciated.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company