On Apr 30, 2011, at 9:34 AM, Kenneth Marshall wrote:
>> I suppose that's what I am going to do on a periodic basis from now
>> on. There is a lot of DELETE/UPDATE activity. But I wonder if the
>> vacuum stuff really should do something that's similar in function?
>> What do the high-end enterprise folks do -- surely they can't be
>> dumping/restoring every quarter or so....or are they?
>> 
>> Anyway, many many thanks to the lovely folks on this list. Much appreciated!
>> 
> 
> The autovacuum and space management in 9.0 is dramatically more effective
> and efficient then that of 8.2. Unless you have an odd corner-case there
> really should be no reason for a periodic dump/restore. This is not your
> grandmother's Oldsmobile... :)

In 10+ years of using Postgres, I've never come across a case where you 
actually *need* to dump and restore on a regular basis. However, you can 
certainly run into scenarios where vacuum simply can't keep up. If your 
restored database is 1/3 the size of the original then this is certainly what 
was happening on your 8.2 setup.

As Kenneth mentioned, 9.0 is far better in this regard than 8.2, though it's 
still possible that you're doing something that will give it fits. I suggest 
that you run a weekly vacuumdb -av, capture that output and run it through 
pgFouine. That will give you a ton of useful information about the amount of 
bloat you have in each table. I would definitely look at anything with over 20% 
bloat.

BTW, in case you're still questioning using Postgres in an enterprise setting; 
all of our production OLTP databases run on Postgres. The largest one is ~1.5TB 
and does over 650TPS on average (with peaks that are much higher). Unplanned 
downtime on that database would cost us well over $100k/hour, and we're storing 
financial information, so data quality issues are not an option (data quality 
was one of the primary reasons we moved away from MySQL in 2006). So yes, you 
can absolutely run very large Postgres databases in a high-workload 
environment. BTW, that's also on version 8.3.
--
Jim C. Nasby, Database Architect                   j...@nasby.net
512.569.9461 (cell)                         http://jim.nasby.net



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