From: | Bryce Nesbitt <bryce1(at)obviously(dot)com> |
---|---|
To: | pgsql-sql(at)postgresql(dot)org |
Cc: | Peter Eisentraut <peter_e(at)gmx(dot)net> |
Subject: | Re: Very slow updates when using IN syntax subselect |
Date: | 2006-02-11 22:43:03 |
Message-ID: | 43EE6877.7080002@obviously.com |
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Lists: | pgsql-sql |
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
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