Re: proposal: lock_time for pg_stat_database

2015-01-16 18:23 GMT+01:00 Jim Nasby <Jim(dot)Nasby(at)bluetreble(dot)com>:

> On 1/16/15 11:00 AM, Pavel Stehule wrote:
>
>> Hi all,
>>
>> some time ago, I proposed a lock time measurement related to query. A
>> main issue was a method, how to show this information. Today proposal is
>> little bit simpler, but still useful. We can show a total lock time per
>> database in pg_stat_database statistics. High number can be signal about
>> lock issues.
>>
>
> Would this not use the existing stats mechanisms? If so, couldn't we do
> this per table? (I realize that won't handle all cases; we'd still need a
> "lock_time_other" somewhere).
>

it can use a current existing stats mechanisms

I afraid so isn't possible to assign waiting time to table - because it
depends on order

>
> Also, what do you mean by 'lock'? Heavyweight? We already have some
> visibility there. What I wish we had was some way to know if we're spending
> a lot of time in a particular non-heavy lock. Actually measuring time
> probably wouldn't make sense but we might be able to count how often we
> fail initial acquisition or something.
>

now, when I am thinking about it, lock_time is not good name - maybe
"waiting lock time" (lock time should not be interesting, waiting is
interesting) - it can be divided to some more categories - in GoodData we
use Heavyweight, pages, and others categories.

> --
> Jim Nasby, Data Architect, Blue Treble Consulting
> Data in Trouble? Get it in Treble! http://BlueTreble.com
>