Horton

Re: proposal - psql - use pager for \watch command

Pavel Stehule <pavel.stehule@gmail.com>

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From: Pavel Stehule <pavel.stehule@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2020-07-01T21:03:30Z
Lists: pgsql-hackers 
st 1. 7. 2020 v 22:41 odesílatel Tom Lane <tgl@sss.pgh.pa.us> napsal:

> Pavel Stehule <pavel.stehule@gmail.com> writes:
> > I propose new psql environment variable PSQL_WATCH_PAGER. When this
> > variable is not empty, then \watch command starts specified pager, and
> > redirect output to related pipe. When pipe is closed - by pager, then
> > \watch cycle is leaved.
>
> I dunno, this just seems really strange.  With any normal pager,
> you'd get completely unusable behavior (per the comments that you
> didn't bother to change).  Also, how would the pager know where
> the boundaries between successive query outputs are?  If it does
> not know, seems like that's another decrement in usability.
>

This feature is designed for specialized pagers - now only pspg can work in
this mode. But pspg is part of RH, Fedora, Debian, and it is available on
almost Unix platforms.

https://github.com/okbob/pspg

the pspg knows the psql output format of \watch statement.

The usability of this combination - psql \watch and pspg is really good.

Regards

Pavel


>                         regards, tom lane
>

Commits

  1. Fix \watch's interaction with libedit on ^C.

  2. Add PSQL_WATCH_PAGER for psql's \watch command.

  3. psql: Show all query results by default

  4. Add a comment warning against use of pg_usleep() for long sleeps.