Re-allow DISTINCT in pl/pgsql expressions.
authorTom Lane <tgl@sss.pgh.pa.us>
Fri, 22 Jan 2021 21:26:22 +0000 (16:26 -0500)
committerTom Lane <tgl@sss.pgh.pa.us>
Fri, 22 Jan 2021 21:26:22 +0000 (16:26 -0500)
commit7cd9765f9bd3397b8d4d0f507021ef848b6d48d2
treef2b0a70620cdb33444cbf34387d2c63db69d9451
parentab66645628d38a7047996b294b213f3048f7ef9b
Re-allow DISTINCT in pl/pgsql expressions.

I'd omitted this from the grammar in commit c9d529848, figuring that
it wasn't worth supporting.  However we already have one complaint,
so it seems that judgment was wrong.  It doesn't require a huge
amount of code, so add it back.  (I'm still drawing the line at
UNION/INTERSECT/EXCEPT though: those'd require an unreasonable
amount of grammar refactoring, and the single-result-row restriction
makes them near useless anyway.)

Also rethink the documentation: this behavior is a property of
all pl/pgsql expressions, not just assignments.

Discussion: https://postgr.es/m/20210122134106.e94c5cd7@mail.verfriemelt.org
doc/src/sgml/plpgsql.sgml
src/backend/parser/analyze.c
src/backend/parser/gram.y