Обсуждение: Autovacuum & Table List Ordering

OK, so i was going through the autovacuum code and i noticed that when we construct the table list to vacuum in a
databaseper run, we don't process them in a particular order. I mean since we pick the list up from pg_class so it may
beordered on oid? but when we select a database we have a priority  algo, which select the db's in XID wraparound 
dangerfirst, and that too the in an order that the db nearest to the XID wraparound is picked first <br /><br />So
wouldn'tit make sense to pick up the tables in a similar order as well? like sorting the list on (deadtuples -
calculatedthreshold) this way we will be vacuuming the tables in more need first.<br /><br />Without an order i can
imaginea scenario where a table which is near a wrap-around or has more dead-rows waiting  or possible having the XID
warparoundwhile another big table takes a lot of time. <br /><br />With the launcher - worker architecture in 8.3 the
situationwill improve as you can have multiple workers vacuuming multiple tables in parallel, but having some order
therewould also help , i would think.<br /><br clear="all" /> Thanks,<br />-- <br />Usama Munir Dar <a
href="http://www.linkedin.com/in/usamadar">http://www.linkedin.com/in/usamadar</a><br/>Consultant Architect<br
/>Cell:+92321 5020666<br />Skype: usamadar <br /> 

Usama Dar escribió:

> So wouldn't it make sense to pick up the tables in a similar order as well?
> like sorting the list on (deadtuples - calculated threshold) this way we
> will be vacuuming the tables in more need first.

Sure, feel free to propose a specific ordering.  I think you would need
to take table size into account too.

Something that's also important to fix while you're doing that is fixing
the "BUG" that is mentioned in the code that Simon griped about not long
ago.

-- 
Alvaro Herrera                                http://www.CommandPrompt.com/
PostgreSQL Replication, Consulting, Custom Development, 24x7 support