Re: atrocious update performance

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От Rosser Schwarz
Тема Re: atrocious update performance
Дата
Msg-id 009901c41b48$8357c860$2500fa0a@CardServices.TCI.com
обсуждение исходный текст
Ответ на Re: atrocious update performance  ("Kevin Barnard" <kbarnard@speedfc.com>)
Ответы possible improvement between G4 and G5  (Qing Zhao <qzhao@quotefx.net>)
Re: atrocious update performance  (Stephan Szabo <sszabo@megazone.bigpanda.com>)
Список pgsql-performance
while you weren't looking, Kevin Barnard wrote:

> Have you added indexes for the custid column for tables
> account.acct accunt.orgacct and note?

They were indexed in the original case, yes.  There was no
need to index them in today's test case, as that was done
purely in attempt to rule in or out foreign key validation
as the cause of the performance hit.  No foreign keys that
might be validated, no need to index the foreign key columns.

> I haven't followed the entire thread but it you have
> cascading FK on those tables without an index on the
> column that could cause your delay.

The issue is that the foreign keys are being validated at
all, when the column being referenced by those foreign keys
(account.cust.custid) is never touched.

Regardless of whether or not the referencing columns are
indexed, validating them at all--in this specific case--is
broken.  The column they refer to is never touched; they
should remain utterly ignorant of whatever happens to other
columns in the same row.

/rls

--
Rosser Schwarz
Total Card, Inc.


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