merging with mysql-5.1-bugteam tree

storage/myisam/ha_myisam.cc

@@ -315,6 +315,7 @@ int table2myisam(TABLE *table_arg, MI_KEYDEF **keydef_out,
       t2_keys          in    Number of keys in second table
       t2_recs          in    Number of records in second table
       strict           in    Strict check switch
+      table            in    handle to the table object
 
   DESCRIPTION
     This function compares two MyISAM definitions. By intention it was done
@@ -330,6 +331,10 @@ int table2myisam(TABLE *table_arg, MI_KEYDEF **keydef_out,
     Otherwise 'strict' flag must be set to 1 and it is not required to pass
     converted dot-frm definition as t1_*.
 
+    For compatibility reasons we relax some checks, specifically:
+    - 4.0 (and earlier versions) always set key_alg to 0.
+    - 4.0 (and earlier versions) have the same language for all keysegs.
+
   RETURN VALUE
     0 - Equal definitions.
     1 - Different definitions.
@@ -344,10 +349,11 @@ int table2myisam(TABLE *table_arg, MI_KEYDEF **keydef_out,
 int check_definition(MI_KEYDEF *t1_keyinfo, MI_COLUMNDEF *t1_recinfo,
                      uint t1_keys, uint t1_recs,
                      MI_KEYDEF *t2_keyinfo, MI_COLUMNDEF *t2_recinfo,
-                     uint t2_keys, uint t2_recs, bool strict)
+                     uint t2_keys, uint t2_recs, bool strict, TABLE *table_arg)
 {
   uint i, j;
   DBUG_ENTER("check_definition");
+  my_bool mysql_40_compat= table_arg && table_arg->s->frm_version < FRM_VER_TRUE_VARCHAR;
   if ((strict ? t1_keys != t2_keys : t1_keys > t2_keys))
   {
     DBUG_PRINT("error", ("Number of keys differs: t1_keys=%u, t2_keys=%u",
@@ -386,8 +392,9 @@ int check_definition(MI_KEYDEF *t1_keyinfo, MI_COLUMNDEF *t1_recinfo,
                             test(t2_keyinfo[i].flag & HA_SPATIAL)));
        DBUG_RETURN(1);
     }
-    if (t1_keyinfo[i].keysegs != t2_keyinfo[i].keysegs ||
-        t1_keyinfo[i].key_alg != t2_keyinfo[i].key_alg)
+    if ((mysql_40_compat &&
+        t1_keyinfo[i].key_alg != t2_keyinfo[i].key_alg) ||
+        t1_keyinfo[i].keysegs != t2_keyinfo[i].keysegs)
     {
       DBUG_PRINT("error", ("Key %d has different definition", i));
       DBUG_PRINT("error", ("t1_keysegs=%d, t1_key_alg=%d",
@@ -417,8 +424,9 @@ int check_definition(MI_KEYDEF *t1_keyinfo, MI_COLUMNDEF *t1_recinfo,
           t1_keysegs_j__type= HA_KEYTYPE_VARBINARY1; /* purecov: inspected */
       }
 
-      if (t1_keysegs_j__type != t2_keysegs[j].type ||
-          t1_keysegs[j].language != t2_keysegs[j].language ||
+      if ((mysql_40_compat &&
+          t1_keysegs[j].language != t2_keysegs[j].language) ||
+          t1_keysegs_j__type != t2_keysegs[j].type ||
           t1_keysegs[j].null_bit != t2_keysegs[j].null_bit ||
           t1_keysegs[j].length != t2_keysegs[j].length)
       {
@@ -671,7 +679,8 @@ int ha_myisam::open(const char *name, int mode, uint test_if_locked)
     }
     if (check_definition(keyinfo, recinfo, table->s->keys, recs,
                          file->s->keyinfo, file->s->rec,
-                         file->s->base.keys, file->s->base.fields, true))
+                         file->s->base.keys, file->s->base.fields,
+                         true, table))
     {
       /* purecov: begin inspected */
       my_errno= HA_ERR_CRASHED;

storage/myisammrg/ha_myisammrg.cc

@@ -137,7 +137,8 @@ extern int table2myisam(TABLE *table_arg, MI_KEYDEF **keydef_out,
 extern int check_definition(MI_KEYDEF *t1_keyinfo, MI_COLUMNDEF *t1_recinfo,
                             uint t1_keys, uint t1_recs,
                             MI_KEYDEF *t2_keyinfo, MI_COLUMNDEF *t2_recinfo,
-                            uint t2_keys, uint t2_recs, bool strict);
+                            uint t2_keys, uint t2_recs, bool strict,
+                            TABLE *table_arg);
 static void split_file_name(const char *file_name,
 			    LEX_STRING *db, LEX_STRING *name);
 
@@ -595,7 +596,7 @@ int ha_myisammrg::attach_children(void)
       if (check_definition(keyinfo, recinfo, keys, recs,
                            u_table->table->s->keyinfo, u_table->table->s->rec,
                            u_table->table->s->base.keys,
-                           u_table->table->s->base.fields, false))
+                           u_table->table->s->base.fields, false, NULL))
       {
         DBUG_PRINT("error", ("table definition mismatch: '%s'",
                              u_table->table->filename));