From: | Tom DalPozzo <t(dot)dalpozzo(at)gmail(dot)com> |
---|---|
To: | Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> |
Cc: | pgsql-general <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: tuple statistics update |
Date: | 2017-04-19 07:28:43 |
Message-ID: | CAK77FCRmys6+cNPa8_53DV=9cfQBM5GdEXsWrtjgH6j5kTdwiQ@mail.gmail.com |
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Thread: | |
Lists: | pgsql-general |
2017-04-18 21:42 GMT+02:00 Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>:
> On 04/17/2017 09:18 AM, Tom DalPozzo wrote:
>
>> Hi, I'm using libpq to insert tuples in my table and keep looking at
>> statistics through psql instead.
>> I noticed that sometimes n_tuple_ins is not updated even after 1 min
>> that my transaction committed.
>> My libpq connection is kept alive. If I close the connection then the
>> stats get updated.
>> I know that stats are not instantaneous, but I thought that after a
>> while that a transaction is committed it would be updated.
>>
>
> Any of this apply?:
>
> https://www.postgresql.org/docs/9.6/static/monitoring-stats.html
>
> "Another important point is that when a server process is asked to display
> any of these statistics, it first fetches the most recent report emitted by
> the collector process and then continues to use this snapshot for all
> statistical views and functions until the end of its current transaction.
> So the statistics will show static information as long as you continue the
> current transaction. Similarly, information about the current queries of
> all sessions is collected when any such information is first requested
> within a transaction, and the same information will be displayed throughout
> the transaction. This is a feature, not a bug, because it allows you to
> perform several queries on the statistics and correlate the results without
> worrying that the numbers are changing underneath you. But if you want to
> see new results with each query, be sure to do the queries outside any
> transaction block. Alternatively, you can invoke pg_stat_clear_snapshot(),
> which will discard the current transaction's statistics snapshot (if any).
> The next use of statistical information will cause a new snapshot to be
> fetched."
>
> Regards
>> Pupillo
>>
>>
I read it, it seems to say that after N millisec that my transaction ends,
stat should be current. I also tried pg_stat_clear_snapshot() with no
success.
Regards
Pupillo
>
>>
>>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com
>
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