Re: [GENERAL] tuple statistics update

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От Tom DalPozzo
Тема Re: [GENERAL] tuple statistics update
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Msg-id CAK77FCQRJzzS_PerYRvv=CypXwE+5mzey6Cp3VF-JB_=_VR9ug@mail.gmail.com
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Ответ на Re: [GENERAL] tuple statistics update  (Tom Lane <tgl@sss.pgh.pa.us>)
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Hi,

2017-04-19 16:37 GMT+02:00 Tom Lane <tgl@sss.pgh.pa.us>:
Tom DalPozzo <t.dalpozzo@gmail.com> writes:
> 2017-04-18 22:06 GMT+02:00 Tom Lane <tgl@sss.pgh.pa.us>:
>> If your session is just sitting, that's not surprising.  I think stats
>> updates are only transmitted to the collector at transaction end (and
>> even then, only if it's been at least N msec since the last transmission
>> from the current session).

> Hi, my transaction ended, that I waited 1 min and queried the stat.
> I had to wait for session end in order to see the updeted stats.
> Did you mean "...to the collector at SESSION end"?

No, I meant what I said.  No amount of just-sitting will cause a session
to do something: it either transmits stats at transaction end or it
doesn't because it thinks it's too soon since its last update.  If you
want to force out the stats, you could wait a second or so and then
do a dummy transaction (even "select 1" will do, in testing).

BTW, a quick look at the code says the threshold is 500 msec, ie,
stats are sent only if it's been at least half a second since the
session's last report.

I tried with a dummy select with no success. I detailed my test in my answer to Adrian Klaver.
I'll avoid to duplicate it here.
Regards
Pupillo


 

                        regards, tom lane

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