Re: Add sub-transaction overflow status in pg_stat_activity

I also want to +1 this this effort. Exposing subtransaction usage is very useful.

It would also be extremely beneficial to add both subtransaction usage and overflow counters to pg_stat_database. 

Monitoring tools that capture deltas on pg_stat_database will be able to generate historical analysis and usage trends of subtransactions.

On 12/7/21, 5:34 PM, "Bossart, Nathan" <bossartn@amazon.com> wrote:

    On 12/6/21, 8:19 PM, "Dilip Kumar" <dilipbalaut@gmail.com> wrote:
    > If the subtransaction cache is overflowed in some of the transactions
    > then it will affect all the concurrent queries as they need to access
    > the SLRU for checking the visibility of each tuple.  But currently
    > there is no way to identify whether in any backend subtransaction is
    > overflowed or what is the current active subtransaction count.
    > Attached patch adds subtransaction count and subtransaction overflow
    > status in pg_stat_activity.  I have implemented this because of the
    > recent complain about the same[1]

    I'd like to give a general +1 to this effort.  Thanks for doing this!
    I've actually created a function to provide this information in the
    past, so I will help review.

    Nathan