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help / color / mirror / Atom feedFrom: Justin Pryzby <[email protected]>
To: Dilip Kumar <[email protected]>
Cc: [email protected]
Subject: Re: Add sub-transaction overflow status in pg_stat_activity
Date: Mon, 6 Dec 2021 23:41:24 -0600
Message-ID: <[email protected]> (raw)
In-Reply-To: <CAFiTN-uvYAofNRaGF4R+u6_OrABdkqNRoX7V6+PP3H_0HuYMwg@mail.gmail.com>
References: <CAFiTN-uvYAofNRaGF4R+u6_OrABdkqNRoX7V6+PP3H_0HuYMwg@mail.gmail.com>
> + <entry role="catalog_table_entry"><para role="column_definition">
> + <structfield>subxact_count</structfield> <type>xid</type>
> + </para>
> + <para>
> + The current backend's active subtransactions count.
subtransaction (no s)
> + Set to true if current backend's subtransaction cache is overflowed.
Say "has overflowed"
> + if (local_beentry->subxact_count > 0)
> + {
> + values[30] = local_beentry->subxact_count;
> + values[31] = local_beentry->subxact_overflowed;
> + }
> + else
> + {
> + nulls[30] = true;
> + nulls[31] = true;
> + }
Why is the subxact count set to NULL instead of zero ?
You added this to pg_stat_activity, which already has a lot of fields.
We talked a few months ago about not adding more fields that weren't commonly
used.
https://www.postgresql.org/message-id/flat/20210426191811.sp3o77doinphyjhu%40alap3.anarazel.de#d96d0...
Since I think this field is usually not interesting to most users of
pg_stat_activity, maybe this should instead be implemented as a function like
pg_backend_get_subxact_status(pid).
People who want to could use it like:
SELECT * FROM pg_stat_activity psa, pg_backend_get_subxact_status(pid) sub;
--
Justin
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Subject: Re: Add sub-transaction overflow status in pg_stat_activity
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