Re: Freeze avoidance of very large table.

On 8/19/15 2:56 AM, Masahiko Sawada wrote:
> The currently regression test for VM is that we just compare between
> the total number of all-visible and all-frozen in VM before and after
> VACUUM, and don't check particular a bit in VM.
> we could substitute it to the ANALYZE command with enough sampling
> number and checking pg_class.relallvisible and pg_class.relallfrozen.

I think this is another indication that we need more than just pg_regress...

> So another way is that diagnostic function for VM is put into
> something contrib (pg_freespacemap or pageinspect), and if we want to
> use such function in production, we can install such extension as in
> the past.

pg_buffercache is very useful as a performance monitoring tool, and I 
view being able to pull statistics about the VM and FM the same way. I'd 
like to see us providing more performance information by default, not less.

I think things like pageinspect are very different; I really can't see 
any use for those beyond debugging (and debugging by an expert at that).
-- 
Jim Nasby, Data Architect, Blue Treble Consulting, Austin TX
Data in Trouble? Get it in Treble! http://BlueTreble.com