Re: Concurrent CREATE INDEX, try 2 (was Re: Reducing

From: Hannu Krosing <hannu(at)skype(dot)net>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Cc: Jochem van Dieten <jochemd(at)gmail(dot)com>, Greg Stark <gsstark(at)mit(dot)edu>, Christopher Kings-Lynne <chriskl(at)familyhealth(dot)com(dot)au>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: Concurrent CREATE INDEX, try 2 (was Re: Reducing
Date: 2005-12-06 21:07:45
Message-ID: 1133903265.3719.37.camel@localhost.localdomain
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Ühel kenal päeval, T, 2005-12-06 kell 16:01, kirjutas Tom Lane:
> Hannu Krosing <hannu(at)skype(dot)net> writes:
> > 1) run a transaction repeatedly, trying to hit a point of no concurrent
> > transactions,
>
> In the sort of 24x7 environment that people are arguing this is needed
> for, it's entirely possible that that will *never* succeed.

My OLTP transactions are usually 5-50ms in length. common sense tells
me, that if I disallow new transactions for 100ms, I am more than likely
to have waited for all existing ones to have finished and can do my 1 ms
of "take snapshot + commit" and let all the waiting transactions to
commence.

If the database is running longer transactions, there can be a GUC to
adjust the time CUNCURRENT CREATE INDEX will wait. For example for
trx'es mostly in 0.5-2 sec range the wait could be set to 3 sec.

-------------
Hannu

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