On Jun 19, 2008, at 8:07 AM, David Fetter wrote:
On Wed, Jun 18, 2008 at 05:39:59PM -0700, Jeff Davis wrote:I was trying to create a more "at-a-glance" view of the pg_locks table.I included the SQL I came up with (after talking to Merlin) at the bottom of this message. The idea is to show any queries that are waiting on a lock, and thequery that currently holds the lock on which those queries are waiting.Is my logic correct?I'm not exactly sure, but it appears to match, at first blush, what's in src/backend/storage/lmgr/lock.c: static const LOCKMASK LockConflicts[] = {
Yeah, if you look at the code, locks are defined as numbers and I believe there's a very simple patter of what conflicts; a higher lock number conflicts with all those that are lower. So, it might be a lot cleaner to have a function that defines numbers for all the lock modes and just test to see if one lock is higher than another.
I think your logic in the view is correct. It might be helpful to also list how long the queries have been running.
I really wish we had some kind of a site for listing useful queries like this...
-- Decibel!, aka Jim C. Nasby, Database Architect decibel@xxxxxxxxxxx Give your computer some brain candy! www.distributed.net Team #1828
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