Hello Pavel,
This is a discussion without actual patch intended for pg12, to be added
to CF 2018-09. The expected end result is either "returned with feedback",
meaning proceed to send some big patch(es), or "rejected", meaning the
project does not want this, no point in submitting something.
please, can you port expression evaluation from pgbench to psql? I miss a
patch.
Indeed, I have not done it yet:-)
This is a pretty large series of patches, which would take a significant
time for developing (me), rewiewing (not me) and committing (with overload
committers). I would not like to end in the "we do not want this feature
at all" state *after* the time has been spent, hence this pre-patch call
for discussion about the feature itself, before diving into coding.
I take note that you are interested in actually having this feature.
I am sure so psql expression evaluation has strong benefit - mainly for
expressions like
\if SERVER_VERSION_NUM >= xxxx
...
\endif
Note that this can already be done by relying on server-side expressions:
SELECT :SERVER_VERSION_NUM >= 110000 AS "version_11_plus" \gset
\if :version_11_plus
...
\endif
Not very elegant, but functional. I'm not sure there is a compelling
reason to have this feature beyond elegance.
--
Fabien.
