Fixed rare bug in MYISAM introduced in 4.0.3 where the index file header was not updated directly after an UPDATE of split dynamic rows.

myisam/mi_locking.c:
  Added DBUG info
myisam/mi_open.c:
  Added DBUG info
myisam/mi_update.c:
  More comments
  Fixed rare bug in MYISAM introduced in 4.0.3 where the index file header
  was not updated directly after an UPDATE of split dynamic rows.
mysql-test/r/myisam.result:
  Added test case for MyISAM UPDATE bug
mysql-test/t/myisam.test:
  Added test case for MyISAM UPDATE bug

myisam/mi_locking.c

@@ -76,6 +76,8 @@ int mi_lock_database(MI_INFO *info, int lock_type)
       }
       if (!count)
       {
+	DBUG_PRINT("info",("changed: %u  w_locks: %u",
+			   (uint) share->changed, share->w_locks));
 	if (share->changed && !share->w_locks)
 	{
 	  share->state.process= share->last_process=share->this_process;
@@ -352,6 +354,8 @@ int _mi_writeinfo(register MI_INFO *info, uint operation)
   int error,olderror;
   MYISAM_SHARE *share=info->s;
   DBUG_ENTER("_mi_writeinfo");
+  DBUG_PRINT("info",("operation: %u  tot_locks: %u", operation,
+		     share->tot_locks));
 
   error=0;
   if (share->tot_locks == 0)
@@ -379,9 +383,7 @@ int _mi_writeinfo(register MI_INFO *info, uint operation)
     my_errno=olderror;
   }
   else if (operation)
-  {
     share->changed= 1;			/* Mark keyfile changed */
-  }
   DBUG_RETURN(error);
 } /* _mi_writeinfo */
 

myisam/mi_open.c

@@ -730,6 +730,7 @@ uint mi_state_info_write(File file, MI_STATE_INFO *state, uint pWrite)
   uchar *ptr=buff;
   uint	i, keys= (uint) state->header.keys,
 	key_blocks=state->header.max_block_size;
+  DBUG_ENTER("mi_state_info_write");
 
   memcpy_fixed(ptr,&state->header,sizeof(state->header));
   ptr+=sizeof(state->header);
@@ -780,10 +781,10 @@ uint mi_state_info_write(File file, MI_STATE_INFO *state, uint pWrite)
   }
 
   if (pWrite & 1)
-     return my_pwrite(file,(char*) buff, (uint) (ptr-buff), 0L,
+    DBUG_RETURN(my_pwrite(file,(char*) buff, (uint) (ptr-buff), 0L,
-		      MYF(MY_NABP | MY_THREADSAFE));
+			  MYF(MY_NABP | MY_THREADSAFE)));
-  else
+  DBUG_RETURN(my_write(file,  (char*) buff, (uint) (ptr-buff),
-    return my_write(file,  (char*) buff, (uint) (ptr-buff), MYF(MY_NABP));
+		       MYF(MY_NABP)));
 }
 
 

myisam/mi_update.c

@@ -94,7 +94,14 @@ int mi_update(register MI_INFO *info, const byte *oldrec, byte *newrec)
 	if (_mi_ft_cmp(info,i,oldrec, newrec))
 	{
 	  if ((int) i == info->lastinx)
+	  {
+	  /*
+	    We are changeing the index we are reading on.  Mark that
+	    the index data has changed and we need to do a full search
+	    when doing read-next
+	  */
 	    key_changed|=HA_STATE_WRITTEN;
+	  }
 	  changed|=((ulonglong) 1 << i);
 	  if (_mi_ft_update(info,i,(char*) old_key,oldrec,newrec,pos))
 	    goto err;
@@ -121,25 +128,36 @@ int mi_update(register MI_INFO *info, const byte *oldrec, byte *newrec)
   }
   /*
     If we are running with external locking, we must update the index file
-    that something has changed
+    that something has changed.
   */
   if (changed || !my_disable_locking)
-    key_changed|= HA_STATE_KEY_CHANGED;
+    key_changed|= HA_STATE_CHANGED;
 
   if (share->calc_checksum)
   {
     info->checksum=(*share->calc_checksum)(info,newrec);
-    key_changed|= HA_STATE_KEY_CHANGED;		/* Must update index file */
+    /* Store new checksum in index file header */
+    key_changed|= HA_STATE_CHANGED;
   }
   {
-    /* Don't update index file if data file is not extended */
+    /*
+      Don't update index file if data file is not extended and no status
+      information changed
+    */
     MI_STATUS_INFO state;
+    ha_rows org_split;
+    my_off_t org_delete_link;
+
     memcpy((char*) &state, (char*) info->state, sizeof(state));
+    org_split=	     share->state.split;
+    org_delete_link= share->state.dellink;
     if ((*share->update_record)(info,pos,newrec))
       goto err;
     if (!key_changed &&
-	memcmp((char*) &state, (char*) info->state, sizeof(state)))
+	(memcmp((char*) &state, (char*) info->state, sizeof(state)) ||
-      key_changed|= HA_STATE_KEY_CHANGED;	/* Must update index file */  
+	 org_split != share->state.split ||
+	 org_delete_link != share->state.dellink))
+      key_changed|= HA_STATE_CHANGED;		/* Must update index file */
   }
   if (auto_key_changed)
     update_auto_increment(info,newrec);
@@ -163,7 +181,7 @@ err:
   DBUG_PRINT("error",("key: %d  errno: %d",i,my_errno));
   save_errno=my_errno;
   if (changed)
-    key_changed|= HA_STATE_KEY_CHANGED;
+    key_changed|= HA_STATE_CHANGED;
   if (my_errno == HA_ERR_FOUND_DUPP_KEY || my_errno == HA_ERR_RECORD_FILE_FULL)
   {
     info->errkey= (int) i;

mysql-test/r/myisam.result

@@ -364,3 +364,25 @@ explain select * from t1 force index (a) where a=0 or a=2;
 table	type	possible_keys	key	key_len	ref	rows	Extra
 t1	range	a	a	4	NULL	4	Using where
 drop table t1,t2;
+create table t1 (a int not null auto_increment primary key, b varchar(255));
+insert into t1 (b) values (repeat('a',100)),(repeat('b',100)),(repeat('c',100));
+update t1 set b=repeat(left(b,1),200) where a=1;
+delete from t1 where (a & 1)= 0;
+update t1 set b=repeat('e',200) where a=1;
+flush tables;
+check table t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+update t1 set b=repeat(left(b,1),255) where a between 1 and 5;
+update t1 set b=repeat(left(b,1),10) where a between 32 and 43;
+update t1 set b=repeat(left(b,1),2) where a between 64 and 66;
+update t1 set b=repeat(left(b,1),65) where a between 67 and 70;
+check table t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+insert into t1 (b) values (repeat('z',100));
+update t1 set b="test" where left(b,1) > 'n';
+check table t1;
+Table	Op	Msg_type	Msg_text
+test.t1	check	status	OK
+drop table t1;

mysql-test/t/myisam.test

@@ -352,3 +352,37 @@ explain select * from t1,t2 force index(c) where t1.a=t2.a;
 explain select * from t1 where a=0 or a=2;
 explain select * from t1 force index (a) where a=0 or a=2;
 drop table t1,t2;
+
+#
+# Test bug when updating a split dynamic row where keys are not changed
+#
+
+create table t1 (a int not null auto_increment primary key, b varchar(255));
+insert into t1 (b) values (repeat('a',100)),(repeat('b',100)),(repeat('c',100));
+update t1 set b=repeat(left(b,1),200) where a=1;
+delete from t1 where (a & 1)= 0;
+update t1 set b=repeat('e',200) where a=1;
+flush tables;
+check table t1;
+
+#
+# check updating with keys
+#
+
+disable_query_log;
+let $1 = 100;
+while ($1)
+{
+  eval insert into t1 (b) values (repeat(char(($1 & 32)+65), $1));
+  dec $1;
+}
+enable_query_log;
+update t1 set b=repeat(left(b,1),255) where a between 1 and 5;
+update t1 set b=repeat(left(b,1),10) where a between 32 and 43;
+update t1 set b=repeat(left(b,1),2) where a between 64 and 66;
+update t1 set b=repeat(left(b,1),65) where a between 67 and 70;
+check table t1;
+insert into t1 (b) values (repeat('z',100));
+update t1 set b="test" where left(b,1) > 'n';
+check table t1;
+drop table t1;