Make datetime bucket seeding independent of SET TIMEZONE =

Author: pdobacz

src/query/anonymization.c

@@ -632,8 +632,9 @@ static hash_t hash_label(Oid type, Datum value, bool is_null)
   if (TypeCategory(type) == TYPCATEGORY_DATETIME)
   {
     char value_as_string[MAXDATELEN + 1];
-    /* Leveraging `json.h` as a way to get style-stable encoding of various datetime types. */
-    JsonEncodeDateTime(value_as_string, value, type, NULL);
+    /* Leveraging `json.h` with UTC to get style-stable encoding of various datetime types. */
+    const int tzp = 0;
+    JsonEncodeDateTime(value_as_string, value, type, &tzp);
     return hash_string(value_as_string);
   }
 

test/expected/datetime.out

@@ -45,3 +45,17 @@ SELECT ts, count(*) FROM test_datetime GROUP BY 1;
  2012-05-14 00:00:00 |     9
 (1 row)
 
+SET TIMEZONE TO 'UTC';
+SELECT tz, count(*) FROM test_datetime GROUP BY 1;
+           tz           | count 
+------------------------+-------
+ 2012-05-14 07:00:00+00 |    11
+(1 row)
+
+SET TIMEZONE TO DEFAULT;
+SELECT tz, count(*) FROM test_datetime GROUP BY 1;
+           tz           | count 
+------------------------+-------
+ 2012-05-14 00:00:00-07 |    11
+(1 row)
+

test/sql/datetime.sql

@@ -38,3 +38,8 @@ SET datestyle = 'SQL';
 SELECT ts, count(*) FROM test_datetime GROUP BY 1;
 SET datestyle = 'ISO';
 SELECT ts, count(*) FROM test_datetime GROUP BY 1;
+
+SET TIMEZONE TO 'UTC';
+SELECT tz, count(*) FROM test_datetime GROUP BY 1;
+SET TIMEZONE TO DEFAULT;
+SELECT tz, count(*) FROM test_datetime GROUP BY 1;