pgsql: Fix reporting of column typmods for multi-row VALUES constructs.

Fix reporting of column typmods for multi-row VALUES constructs.

expandRTE() and get_rte_attribute_type() reported the exprType() and
exprTypmod() values of the expressions in the first row of the VALUES as
being the column type/typmod returned by the VALUES RTE.  That's fine for
the data type, since we coerce all expressions in a column to have the same
common type.  But we don't coerce them to have a common typmod, so it was
possible for rows after the first one to return values that violate the
claimed column typmod.  This leads to the incorrect result seen in bug
#14448 from Hassan Mahmood, as well as some other corner-case misbehaviors.

The desired behavior is the same as we use in other type-unification
cases: report the common typmod if there is one, but otherwise return -1
indicating no particular constraint.  It's cheap for transformValuesClause
to determine the common typmod while transforming a multi-row VALUES, but
it'd be less cheap for expandRTE() and get_rte_attribute_type() to
re-determine that info every time they're asked --- possibly a lot less
cheap, if the VALUES has many rows.  Therefore, the best fix is to record
the common typmods explicitly in a list in the VALUES RTE, as we were
already doing for column collations.  This looks quite a bit like what
we're doing for CTE RTEs, so we can save a little bit of space and code by
unifying the representation for those two RTE types.  They both now share
coltypes/coltypmods/colcollations fields.  (At some point it might seem
desirable to populate those fields for all RTE types; but right now it
looks like constructing them for other RTE types would add more code and
cycles than it would save.)

The RTE change requires a catversion bump, so this fix is only usable
in HEAD.  If we fix this at all in the back branches, the patch will
need to look quite different.

Report: https://postgr.es/m/20161205143037.4377.60754@wrigleys.postgresql.org
Discussion: https://postgr.es/m/27429.1480968538@sss.pgh.pa.us

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/0b78106cd4651ad7867036a463ec743f6d3d2e86

Modified Files
--------------
src/backend/nodes/copyfuncs.c             |  7 +--
src/backend/nodes/equalfuncs.c            |  7 +--
src/backend/nodes/outfuncs.c              | 10 ++--
src/backend/nodes/readfuncs.c             | 10 ++--
src/backend/optimizer/plan/setrefs.c      |  7 +--
src/backend/parser/analyze.c              | 54 +++++++++++++-----
src/backend/parser/parse_relation.c       | 94 ++++++++-----------------------
src/include/catalog/catversion.h          |  2 +-
src/include/nodes/parsenodes.h            | 15 +++--
src/include/parser/parse_relation.h       |  4 +-
src/test/regress/expected/create_view.out | 37 ++++++++++++
src/test/regress/sql/create_view.sql      | 13 +++++
12 files changed, 151 insertions(+), 109 deletions(-)