Re: INTERVAL MINUTE TO SECOND didn't do what I thought it would do

On 1/8/25 11:00 AM, Ron Johnson wrote:
> PG 14.13
>
> The goal of "(now() - query_start)::INTERVAL MINUTE TO SECOND" column is
> to see how many minutes and seconds ago that the query started.  (Why?
> Because that's useful to me, and the people I show the output to when
> queries run for more than a few minutes.  We don't need to see hours and
> days; just the total MMMMM:SS.mmm.)
>
> I'd hoped that ::INTERVAL MINUTE TO SECOND would do the trick, but
> MINUTE TO SECOND seems to be ignored.

From here:

https://www.postgresql.org/docs/current/datatype-datetime.html#DATATYPE-INTERVAL-INPUT

"Also, field values “to the right” of the least significant field
allowed by the fields specification are silently discarded. For example,
writing INTERVAL '1 day 2:03:04' HOUR TO MINUTE results in dropping the
seconds field, but not the day field."

>
> Is there cast magic that does what I want?

The only way I can think of extract the epoch from the interval and pass
to a function that builds what you want.

>
> TAPc=# select pid
>        ,datname as db, usename
>        ,to_char(query_start, 'YYYY-MM-DD HH24:MI:SS.MS <http://SS.MS>')
> as  qry_start
>        ,(now() - query_start)::INTERVAL MINUTE TO SECOND as qry_elapsed
>        ,cast(state as char(11)) as state
> from pg_stat_activity
> WHERE pid != pg_backend_pid()
> and state != 'idle';
>    pid   |  db  |  usename   |        qry_start        |
> qry_elapsed       |    state
> ---------+------+------------+-------------------------+-------------------------+-------------
>   657996 |      | replicator | 2024-11-11 21:03:00.992 | 57 days
> 16:38:22.342449 | active
>  4070070 | TAPc | TAP        | 2025-01-08 13:41:23.202 |
> 00:00:00.132817         | active
>  4070069 | TAPc | TAP        | 2025-01-08 13:41:23.140 |
> 00:00:00.194222         | active
>  4070065 | TAPc | TAP        | 2025-01-08 13:41:23.238 |
> 00:00:00.096418         | active
> (4 rows)
>
>
> --
> Death to <Redacted>, and butter sauce.
> Don't boil me, I'm still alive.
> <Redacted> lobster!

--
Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com