The patch that is applied at the end of the email makes sure that these

conditions are always met. The patch can be applied to any version
of Postgres95 from 1.02 to 1.05. After applying the patch, queries
using indices on bpchar and varchar fields should (hopefully ;-) )
always return the same tuple set regardless to the fact whether
indices are used or not.

Submitted by: Gerhard Reithofer 

diff --git a/src/backend/utils/adt/varchar.c b/src/backend/utils/adt/varchar.c
index f33295d27db6f00cf72fdf5eadcdca6190ea493f..025c5a575656f33c90627c45d75c65f85fa7cff8 100644 (file)
--- a/src/backend/utils/adt/varchar.c
+++ b/src/backend/utils/adt/varchar.c
@@ -7,7 +7,7 @@
  *
  *
  * IDENTIFICATION
- *    $Header: /cvsroot/pgsql/src/backend/utils/adt/varchar.c,v 1.2 1996/07/15 19:11:23 scrappy Exp $
+ *    $Header: /cvsroot/pgsql/src/backend/utils/adt/varchar.c,v 1.3 1996/08/26 20:38:52 scrappy Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -245,13 +245,18 @@ int32
 bpcharle(char *arg1, char *arg2)
 {
     int len1, len2;
+    int cmp;
 
     if (arg1 == NULL || arg2 == NULL)
    return((int32) 0);
     len1 = bcTruelen(arg1);
     len2 = bcTruelen(arg2);
 
-    return(strncmp(arg1+4, arg2+4, Min(len1,len2)) <= 0);
+    cmp = strncmp(arg1+4, arg2+4, Min(len1,len2));
+    if (0 == cmp)
+      return (int32)(len1 <= len2 ? 1 : 0);
+    else
+      return (int32)(cmp <= 0);
 }
 
 int32
@@ -276,24 +281,34 @@ int32
 bpcharge(char *arg1, char *arg2)
 {
     int len1, len2;
+    int cmp;
 
     if (arg1 == NULL || arg2 == NULL)
    return((int32) 0);
     len1 = bcTruelen(arg1);
     len2 = bcTruelen(arg2);
 
-    return(strncmp(arg1+4, arg2+4, Min(len1,len2)) >= 0);
+    cmp = strncmp(arg1+4, arg2+4, Min(len1,len2));
+    if (0 == cmp)
+      return (int32)(len1 >= len2 ? 1 : 0);
+    else
+      return (int32)(cmp >= 0);
 }
 
 int32
 bpcharcmp(char *arg1, char *arg2)
 {
     int len1, len2;
+    int cmp;
 
     len1 = bcTruelen(arg1);
     len2 = bcTruelen(arg2);
 
-    return(strncmp(arg1+4, arg2+4, Min(len1,len2)));
+    cmp = strncmp(arg1+4, arg2+4, Min(len1,len2));
+    if ((0 == cmp) && (len1 != len2))
+      return (int32)(len1 < len2 ? -1 : 1);
+    else
+      return cmp;
 }
 
 /*****************************************************************************
@@ -369,13 +384,18 @@ int32
 varcharle(char *arg1, char *arg2)
 {
     int len1, len2;
+    int cmp;
 
     if (arg1 == NULL || arg2 == NULL)
    return((int32) 0);
     len1 = vcTruelen(arg1);
     len2 = vcTruelen(arg2);
 
-    return(strncmp(arg1+4, arg2+4, Min(len1,len2)) <= 0);
+    cmp = strncmp(arg1+4, arg2+4, Min(len1,len2));
+    if (0 == cmp)
+      return (int32)( len1 <= len2 ? 1 : 0);
+    else
+      return (int32)(cmp <= 0);
 }
 
 int32
@@ -400,24 +420,34 @@ int32
 varcharge(char *arg1, char *arg2)
 {
     int len1, len2;
+    int cmp;
 
     if (arg1 == NULL || arg2 == NULL)
    return((int32) 0);
     len1 = vcTruelen(arg1);
     len2 = vcTruelen(arg2);
 
-    return(strncmp(arg1+4, arg2+4, Min(len1,len2)) >= 0);
+    cmp = strncmp(arg1+4, arg2+4, Min(len1,len2));
+    if (0 == cmp)
+      return (int32)(len1 >= len2 ? 1 : 0);
+    else 
+      return (int32)(cmp >= 0);
+
 }
 
 int32
 varcharcmp(char *arg1, char *arg2)
 {
     int len1, len2;
+    int cmp;
 
     len1 = vcTruelen(arg1);
     len2 = vcTruelen(arg2);
-
-    return(strncmp(arg1+4, arg2+4, Min(len1,len2)));
+    cmp = (strncmp(arg1+4, arg2+4, Min(len1,len2)));
+    if ((0 == cmp) && (len1 != len2))
+      return (int32)(len1 < len2 ? -1 : 1);
+    else
+      return (int32)(cmp);
 }
 
 /*****************************************************************************