Re: Lock Wait Statistics (next commitfest)

Mark Kirkwood <markir@paradise.net.nz>

From: Mark Kirkwood <markir@paradise.net.nz>
To: Jaime Casanova <jcasanov@systemguards.com.ec>
Cc: pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2009-07-25T00:29:01Z
Lists: pgsql-hackers
Mark Kirkwood wrote:
> Jaime Casanova wrote:
>> On Fri, Jul 17, 2009 at 3:38 AM, Mark 
>> Kirkwood<markir@paradise.net.nz> wrote:
>>  
>>> With respect to the sum of wait times being not very granular, yes - 
>>> quite
>>> true. I was thinking it is useful to be able to answer the question 
>>> 'where
>>> is my wait time being spent' - but it hides cases like the one you 
>>> mention.
>>> What would you like to see?  would max and min wait times be a useful
>>> addition, or are you thinking along different lines?
>>>
>>>     
>>
>> track number of locks, sum of wait times, max(wait time).
>> but actually i started to think that the best is just make use of
>> log_lock_waits send the logs to csvlog and analyze there...
>>
>>   
> Right - I'll look at adding max (at least) early next week.
>

I'm also thinking of taking a look at amalgamating transaction type lock 
waits. This seems like a good idea because:

 - individually, and viewed at a later date, I don't think they 
individual detail is going to be useful
 - there will be a lot of them
 - I think the statistical data (count, sum elapsed, max elapsed) may be 
sufficiently interesting

Cheers

Mark