Thread: pgsql: Add transform functions for AT TIME ZONE.

Add transform functions for AT TIME ZONE.

This makes "ALTER TABLE tabname ALTER tscol TYPE ... USING tscol AT TIME
ZONE 'UTC'" skip rewriting the table when altering from "timestamp" to
"timestamptz" or vice versa.  While it would be nicer still to optimize
this in the absence of the USING clause given timezone==UTC, transform
functions must consult IMMUTABLE facts only.

Branch
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master

Details
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http://git.postgresql.org/pg/commitdiff/b8a18ad4850ea5ad7884aa6ab731fd392e73b4ad

Modified Files
--------------
src/backend/utils/adt/timestamp.c |  128 +++++++++++++++++++++++++++++++++++++
src/include/catalog/catversion.h  |    2 +-
src/include/catalog/pg_proc.h     |   12 ++--
src/include/utils/timestamp.h     |    2 +
4 files changed, 139 insertions(+), 5 deletions(-)