From: Date: April 12 2007 1:47pm
Subject: bk commit into 5.0 tree (svoj:1.2439) BUG#27516
List-Archive: http://lists.mysql.com/commits/24382
X-Bug: 27516
Message-Id: <20070412114728.78EE041CEC6@june.myoffice.izhnet.ru>

Below is the list of changes that have just been committed into a local
5.0 repository of svoj. When svoj does a push these changes will
be propagated to the main repository and, within 24 hours after the
push, to the public repository.
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see http://dev.mysql.com/doc/mysql/en/installing-source-tree.html

ChangeSet@stripped, 2007-04-12 16:47:25+05:00, svoj@stripped +1 -0
  BUG#27516 - divide by zero crash during optimize table
  
  When a table status is requested by statement like SHOW TABLE
  STATUS and there is another statement (e.g. DELETE) sets
  number of records to 0 concurrently, we may get division by
  zero error, which crashes a server.
  
  This is fixed by using thread local variable x->records instead
  of shared info->state->records when we check if it is zero and
  divide by it.

  myisam/mi_info.c@stripped, 2007-04-12 16:47:23+05:00, svoj@stripped +3 -3
    Information schema does not lock a table when it requests table
    state info. If another thread sets info->state->records to 0
    after we check if it is 0 and before we divide by it we may get
    division by zero error.
    
    Check and divide by local x->records variable instead of shared
    info->state->records.

# This is a BitKeeper patch.  What follows are the unified diffs for the
# set of deltas contained in the patch.  The rest of the patch, the part
# that BitKeeper cares about, is below these diffs.
# User:	svoj
# Host:	june.mysql.com
# Root:	/home/svoj/devel/mysql/BUG27516/mysql-5.0-engines

--- 1.17/myisam/mi_info.c	2006-12-31 00:02:04 +04:00
+++ 1.18/myisam/mi_info.c	2007-04-12 16:47:23 +05:00
@@ -57,9 +57,9 @@ int mi_status(MI_INFO *info, register MI
 
     x->keys	 	= share->state.header.keys;
     x->check_time	= share->state.check_time;
-    x->mean_reclength	= info->state->records ?
-      (ulong) ((info->state->data_file_length-info->state->empty)/
-	       info->state->records) : (ulong) share->min_pack_length;
+    x->mean_reclength= x->records ?
+                       (ulong) ((x->data_file_length - x->delete_length) /
+                                 x->records) : (ulong) share->min_pack_length;
   }
   if (flag & HA_STATUS_ERRKEY)
   {