Avoid calling select_default_timezone() when backing out an unwanted TZ

setting.  This is a temporary kluge to keep Alvaro happy; eventually we
should fix the TZ library API to make the problem really go away.

diff --git a/src/backend/commands/variable.c b/src/backend/commands/variable.c
index 45ed717951ebdc92172fb443f29b5136bcae40df..58cf97408f3193c46338029c780488a5191d8ef7 100644 (file)
--- a/src/backend/commands/variable.c
+++ b/src/backend/commands/variable.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/commands/variable.c,v 1.95 2004/05/21 05:07:57 tgl Exp $
+ *       $PostgreSQL: pgsql/src/backend/commands/variable.c,v 1.96 2004/05/23 23:12:11 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -329,9 +329,13 @@ assign_timezone(const char *value, bool doit, GucSource source)
                         * Otherwise assume it is a timezone name.
                         *
                         * We have to actually apply the change before we can have any
-                        * hope of checking it.  So, save the old value in case we
-                        * have to back out.  We have to copy since pg_get_current_timezone
+                        * hope of checking it.  So, save the old value in case we have
+                        * to back out.  We have to copy since pg_get_current_timezone
                         * returns a pointer to its static state.
+                        *
+                        * This would all get a lot simpler if the TZ library had a better
+                        * API that would let us look up and test a timezone name without
+                        * making it the default.
                         */
                        const char *cur_tz;
                        char       *save_tz;
@@ -361,8 +365,31 @@ assign_timezone(const char *value, bool doit, GucSource source)
                                 */
                                if (save_tz)
                                        pg_tzset(save_tz);
-                               else                    /* TZ library not initialized yet */
-                                       select_default_timezone();
+                               else
+                               {
+                                       /*
+                                        * TZ library wasn't initialized yet.  Annoyingly, we will
+                                        * come here during startup because guc-file.l checks
+                                        * the value with doit = false before actually applying.
+                                        * The best approach seems to be as follows:
+                                        *
+                                        * 1. known && acceptable: leave the setting in place,
+                                        * since we'll apply it soon anyway.  This is mainly
+                                        * so that any log messages printed during this interval
+                                        * are timestamped with the user's requested timezone.
+                                        *
+                                        * 2. known && !acceptable: revert to GMT for lack of
+                                        * any better idea.  (select_default_timezone() may get
+                                        * called later to undo this.)
+                                        *
+                                        * 3. !known: no need to do anything since TZ library
+                                        * did not change its state.
+                                        *
+                                        * Again, this should all go away sometime soon.
+                                        */
+                                       if (known && !acceptable)
+                                               pg_tzset("GMT");
+                               }
                                /* Complain if it was bad */
                                if (!known)
                                {