From: | Tarvi Pillessaar <tarvip(at)gmail(dot)com> |
---|---|
To: | Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> |
Cc: | pgsql-hackers(at)postgresql(dot)org |
Subject: | Re: Detail part for still waiting for lock log message |
Date: | 2013-08-27 16:40:40 |
Message-ID: | 521CD688.60105@gmail.com |
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Thread: | |
Lists: | pgsql-hackers |
Thank you for feedback.
On 26.08.2013 22:20, Alvaro Herrera wrote:
> 1. this assumes there is only one holder, which is not correct.
> (Consider two backends holding shared lock on something and another one
> stuck trying to acquire exclusive)
Hmm, true. Then it's not that simple as I thought in first place.
I guess it is possible to find all those backends that are holding that
shared lock, but i'm not sure about the usefulness anymore as this list
can be huge.
> 2. I think pgstat_get_backend_current_activity() can be helpful.
Yes, I saw that function, but i also wanted tx start time.
> 3. Doesn't this risk excessive overhead?
About the overhead, i may be wrong, but i was thinking that that
particular backend will be put to sleep anyway and also in normal
workload such log messages are not very common (or at least shouldn't be).
> Can the other backends be gone
> (or done with the lock) before the report has completed? If this
> happens, is there a problem?
That's why i have added check if other backend is found etc, but maybe i
missed something. This is one of reasons why i wanted feedback.
Regards
Tarvi Pillessaar
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