Test for "current" time by comparing against "now".

src/test/regress/expected/datetime.out

@@ -36,15 +36,28 @@ one
   1
 (1 row)
 
-QUERY: INSERT INTO DATETIME_TBL VALUES ('current');
-QUERY: BEGIN;
-QUERY: INSERT INTO DATETIME_TBL VALUES ('now');
+QUERY: SELECT 'now'::datetime - 'current'::datetime AS ZeroSecs;
+zerosecs
+--------
+@ 0     
+(1 row)
+
 QUERY: SELECT count(*) AS one FROM DATETIME_TBL WHERE d1 = 'now'::datetime;
 one
 ---
   1
 (1 row)
 
+QUERY: DELETE FROM DATETIME_TBL;
+QUERY: INSERT INTO DATETIME_TBL VALUES ('current');
+QUERY: BEGIN;
+QUERY: INSERT INTO DATETIME_TBL VALUES ('now');
+QUERY: SELECT count(*) AS two FROM DATETIME_TBL WHERE d1 = 'now'::datetime;
+two
+---
+  2
+(1 row)
+
 QUERY: END;
 QUERY: DELETE FROM DATETIME_TBL;
 QUERY: INSERT INTO DATETIME_TBL VALUES ('invalid');

src/test/regress/sql/datetime.sql

@@ -3,7 +3,7 @@
 CREATE TABLE DATETIME_TBL( d1 datetime);
 
 -- Shorthand values
--- Not testable since these are not constant for regression testing.
+-- Not directly testable since these are not constant for regression testing.
 -- So, just try to test parser and hope for the best - tgl 97/04/26
 INSERT INTO DATETIME_TBL VALUES ('current');
 INSERT INTO DATETIME_TBL VALUES ('now');
@@ -19,10 +19,15 @@ SELECT count(*) AS one FROM DATETIME_TBL WHERE d1 = 'yesterday'::datetime;
 SELECT count(*) AS one FROM DATETIME_TBL WHERE d1 = 'today'::datetime + '1 day'::timespan;
 SELECT count(*) AS one FROM DATETIME_TBL WHERE d1 = 'today'::datetime - '1 day'::timespan;
 
+SELECT 'now'::datetime - 'current'::datetime AS ZeroSecs;
+SELECT count(*) AS one FROM DATETIME_TBL WHERE d1 = 'now'::datetime;
+DELETE FROM DATETIME_TBL;
+
+-- verify uniform transaction time within transaction block
 INSERT INTO DATETIME_TBL VALUES ('current');
 BEGIN;
 INSERT INTO DATETIME_TBL VALUES ('now');
-SELECT count(*) AS one FROM DATETIME_TBL WHERE d1 = 'now'::datetime;
+SELECT count(*) AS two FROM DATETIME_TBL WHERE d1 = 'now'::datetime;
 END;
 DELETE FROM DATETIME_TBL;