Re: update query taking too long

[Richard Huxton <dev(at)archonet(dot)com>]

Chris wrote:
> db=# UPDATE email_upd_test SET domainname=substring(email from 
> position('@' in email));
> UPDATE 1000000
> Time: 43796.030 ms
>
> I think I'm I/O bound from my very limited understanding of vmstat.

Well, 43 seconds to update 1 million rows suggests your real query 
should be complete in a few minutes, even if your real table has more 
columns.

Could you check again and just make sure you don't have a foreign key 
referencing this table? I suspect a large table without an index on the 
referencing column.

If you can't see anything, cancel the long-running query, run VACUUM 
FULL VERBOSE on the table, ANALYSE VERBOSE and then try it again. 
There's something very odd here.

--
  Richard Huxton
  Archonet Ltd