pgsql: Extend DomainHasConstraints() to optionally check constraint vol

Extend DomainHasConstraints() to optionally check constraint volatility

Add an optional bool *has_volatile output parameter to
DomainHasConstraints(). When non-NULL, the function checks whether any
CHECK constraint contains a volatile expression. Callers that don't
need this information pass NULL and get the same behavior as before.

This is needed by a subsequent commit that enables the fast default
optimization for domains with non-volatile constraints: we can safely
evaluate such constraints once at ALTER TABLE time, but volatile
constraints require a full table rewrite.

Author: Jian He <jian(dot)universality(at)gmail(dot)com>
Reviewed-by: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
Reviewed-by: Andrew Dunstan <andrew(at)dunslane(dot)net>
Reviewed-by: Viktor Holmberg <viktor(dot)holmberg(at)aiven(dot)io>
Discussion: https://postgr.es/m/CACJufxE_+iZBR1i49k_AHigppPwLTJi6km8NOsC7FWvKdEmmXg@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/487cf2cbd2f5a32cf9756eb9bd6dbf9f3956c8b7

Modified Files
--------------
src/backend/commands/copyfrom.c | 2 +-
src/backend/commands/tablecmds.c | 4 ++--
src/backend/executor/execExpr.c | 2 +-
src/backend/optimizer/util/clauses.c | 2 +-
src/backend/parser/parse_expr.c | 2 +-
src/backend/utils/cache/typcache.c | 27 +++++++++++++++++++++++++--
src/include/utils/typcache.h | 2 +-
7 files changed, 32 insertions(+), 9 deletions(-)