Fix varstr_cmp's special case for UTF8 encoding on Windows so that strings

that are reported as "equal" by wcscoll() are checked to see if they really
are bitwise equal, and are sorted per strcmp() if not.  We made this happen
a couple of years ago in the regular code path, but it unaccountably got
left out of the Windows/UTF8 case (probably brain fade on my part at the
time).  As in the prior set of changes, affected users may need to reindex
indexes on textual columns.

Backpatch as far as 8.2, which is the oldest release we are still supporting
on Windows.

diff --git a/src/backend/utils/adt/varlena.c b/src/backend/utils/adt/varlena.c
index 52adbbb163f8f67f48a7ac34e9fef1a11d1065cf..75832856b6c7e89af7e4295929c9a447648a3e2f 100644 (file)
--- a/src/backend/utils/adt/varlena.c
+++ b/src/backend/utils/adt/varlena.c
@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *       $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.162 2008/01/01 19:45:53 momjian Exp $
+ *       $PostgreSQL: pgsql/src/backend/utils/adt/varlena.c,v 1.163 2008/03/13 18:31:56 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1003,6 +1003,19 @@ varstr_cmp(char *arg1, int len1, char *arg2, int len2)
                                ereport(ERROR,
                                                (errmsg("could not compare Unicode strings: %m")));
 
+                       /*
+                        * In some locales wcscoll() can claim that nonidentical strings
+                        * are equal.  Believing that would be bad news for a number of
+                        * reasons, so we follow Perl's lead and sort "equal" strings
+                        * according to strcmp (on the UTF-8 representation).
+                        */
+                       if (result == 0)
+                       {
+                               result = strncmp(arg1, arg2, Min(len1, len2));
+                               if ((result == 0) && (len1 != len2))
+                                       result = (len1 < len2) ? -1 : 1;
+                       }
+
                        if (a1p != a1buf)
                                pfree(a1p);
                        if (a2p != a2buf)