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.

3 files changed, 11 insertions, 5 deletions

diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 7ed743df970..508741fd443 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -53,6 +53,6 @@
  */
 
 /*							yyyymmddN */
-#define CATALOG_VERSION_NO	201502221
+#define CATALOG_VERSION_NO	201503011
 
 #endif
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 4268b99416e..b8a36601228 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -1155,7 +1155,9 @@ DATA(insert OID = 999 (  lseg_eq		   PGNSP PGUID 12 1 0 0 0 f f f t t f i 2 0 16
 
 /* OIDS 1000 - 1999 */
 
-DATA(insert OID = 1026 (  timezone		   PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 1114 "1186 1184" _null_ _null_ _null_ _null_ timestamptz_izone _null_ _null_ _null_ ));
+DATA(insert OID = 3994 (  timestamp_izone_transform PGNSP PGUID 12 1 0 0 0 f f f f t f i 1 0 2281 "2281" _null_ _null_ _null_ _null_ timestamp_izone_transform _null_ _null_ _null_ ));
+DESCR("transform a time zone adjustment");
+DATA(insert OID = 1026 (  timezone		   PGNSP PGUID 12 1 0 0 timestamp_izone_transform f f f f t f i 2 0 1114 "1186 1184" _null_ _null_ _null_ _null_ timestamptz_izone _null_ _null_ _null_ ));
 DESCR("adjust timestamp to new time zone");
 
 DATA(insert OID = 1031 (  aclitemin		   PGNSP PGUID 12 1 0 0 0 f f f f t f s 1 0 1033 "2275" _null_ _null_ _null_ _null_ aclitemin _null_ _null_ _null_ ));
@@ -1269,7 +1271,9 @@ DATA(insert OID = 1156 (  timestamptz_ge   PGNSP PGUID 12 1 0 0 0 f f f t t f i
 DATA(insert OID = 1157 (  timestamptz_gt   PGNSP PGUID 12 1 0 0 0 f f f t t f i 2 0 16 "1184 1184" _null_ _null_ _null_ _null_ timestamp_gt _null_ _null_ _null_ ));
 DATA(insert OID = 1158 (  to_timestamp	   PGNSP PGUID 14 1 0 0 0 f f f f t f i 1 0 1184 "701" _null_ _null_ _null_ _null_ "select (''epoch''::pg_catalog.timestamptz + $1 * ''1 second''::pg_catalog.interval)" _null_ _null_ _null_ ));
 DESCR("convert UNIX epoch to timestamptz");
-DATA(insert OID = 1159 (  timezone		   PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 1114 "25 1184" _null_ _null_ _null_ _null_	timestamptz_zone _null_ _null_ _null_ ));
+DATA(insert OID = 3995 (  timestamp_zone_transform PGNSP PGUID 12 1 0 0 0 f f f f t f i 1 0 2281 "2281" _null_ _null_ _null_ _null_ timestamp_zone_transform _null_ _null_ _null_ ));
+DESCR("transform a time zone adjustment");
+DATA(insert OID = 1159 (  timezone		   PGNSP PGUID 12 1 0 0 timestamp_zone_transform f f f f t f i 2 0 1114 "25 1184" _null_ _null_ _null_ _null_	timestamptz_zone _null_ _null_ _null_ ));
 DESCR("adjust timestamp to new time zone");
 
 DATA(insert OID = 1160 (  interval_in	   PGNSP PGUID 12 1 0 0 0 f f f f t f s 3 0 1186 "2275 26 23" _null_ _null_ _null_ _null_ interval_in _null_ _null_ _null_ ));
@@ -2996,9 +3000,9 @@ DESCR("date difference preserving months and years");
 DATA(insert OID = 2059 (  age				PGNSP PGUID 14 1 0 0 0 f f f f t f s 1 0 1186 "1114" _null_ _null_ _null_ _null_ "select pg_catalog.age(cast(current_date as timestamp without time zone), $1)" _null_ _null_ _null_ ));
 DESCR("date difference from today preserving months and years");
 
-DATA(insert OID = 2069 (  timezone			PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 1184 "25 1114" _null_ _null_ _null_ _null_ timestamp_zone _null_ _null_ _null_ ));
+DATA(insert OID = 2069 (  timezone			PGNSP PGUID 12 1 0 0 timestamp_zone_transform f f f f t f i 2 0 1184 "25 1114" _null_ _null_ _null_ _null_ timestamp_zone _null_ _null_ _null_ ));
 DESCR("adjust timestamp to new time zone");
-DATA(insert OID = 2070 (  timezone			PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 1184 "1186 1114" _null_ _null_ _null_ _null_	timestamp_izone _null_ _null_ _null_ ));
+DATA(insert OID = 2070 (  timezone			PGNSP PGUID 12 1 0 0 timestamp_izone_transform f f f f t f i 2 0 1184 "1186 1114" _null_ _null_ _null_ _null_	timestamp_izone _null_ _null_ _null_ ));
 DESCR("adjust timestamp to new time zone");
 DATA(insert OID = 2071 (  date_pl_interval	PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 1114 "1082 1186" _null_ _null_ _null_ _null_	date_pl_interval _null_ _null_ _null_ ));
 DATA(insert OID = 2072 (  date_mi_interval	PGNSP PGUID 12 1 0 0 0 f f f f t f i 2 0 1114 "1082 1186" _null_ _null_ _null_ _null_	date_mi_interval _null_ _null_ _null_ ));
diff --git a/src/include/utils/timestamp.h b/src/include/utils/timestamp.h
index 70118f599c6..530fef1915e 100644
--- a/src/include/utils/timestamp.h
+++ b/src/include/utils/timestamp.h
@@ -161,7 +161,9 @@ extern Datum timestamp_trunc(PG_FUNCTION_ARGS);
 extern Datum interval_trunc(PG_FUNCTION_ARGS);
 extern Datum timestamp_part(PG_FUNCTION_ARGS);
 extern Datum interval_part(PG_FUNCTION_ARGS);
+extern Datum timestamp_zone_transform(PG_FUNCTION_ARGS);
 extern Datum timestamp_zone(PG_FUNCTION_ARGS);
+extern Datum timestamp_izone_transform(PG_FUNCTION_ARGS);
 extern Datum timestamp_izone(PG_FUNCTION_ARGS);
 extern Datum timestamp_timestamptz(PG_FUNCTION_ARGS);