From: Bryce Nesbitt <bryce1@obviously.com>
To: pgsql-sql@postgresql.org
Cc: Peter Eisentraut <peter_e@gmx.net>
Subject: Re: Very slow updates when using IN syntax subselect
Date: Sat, 11 Feb 2006 14:43:03 -0800
Message-ID: <43EE6877.7080002@obviously.com> (raw)
In-Reply-To: <200602112134.57572.peter_e@gmx.net>
References: <43ECFF0B.80905@obviously.com>
<7972.1139672862@sss.pgh.pa.us>
<43EE3F77.6020108@obviously.com>
<200602112134.57572.peter_e@gmx.net>
Peter Eisentraut wrote:
> Bryce Nesbitt wrote:
>
>>> It seems pretty clear that you've never vacuumed nor analyzed these
>>> tables ... else the planner would have some clue about their sizes.
>>> Do that and then see what you get.
>>>
>> They occur in fine time. That's good, thanks. But jeeze, can't
>> postgres figure this out for itself?
>>
>
> I'm sure you wouldn't appreciate it if PostgreSQL did a full table scan
> before each query to figure out the total size of the involved tables.
>
Nope.
But let's say the query optimizer thought the table had one row.
The the query starts, and 111,000 rows later...
It seems that a mismatch between the static table size, and the actual
one counted as you go, would be a quick
check. That could set a flag for later background processing....
-Bryce
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: bryce1@obviously.com, peter_e@gmx.net
Subject: Re: Very slow updates when using IN syntax subselect
In-Reply-To: <43EE6877.7080002@obviously.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox