bk commit into 5.0 tree (svoj:1.2294) BUG#23526

[Sergey Vojtovich]

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5.0 repository of svoj. When svoj does a push these changes will
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ChangeSet@stripped, 2006-11-09 15:55:27+04:00, svoj@stripped +3 -0
  BUG#23526 - show table status reports incorrect values for MyISAM tables
  
  This problem could happen when show table status get outdated copy
  of TABLE object from table cache.
  
  MyISAM updates state info when external_lock() method is called. Though
  I_S does not lock a table to avoid deadlocks. If I_S opens a table which
  is in a table cache it will likely get outdated state info copy.
  
  In this case shared state copy is more recent than local copy. This problem
  is fixed by reading state info directly from share not locking it.
  
  As a side effect show table status will report outdated state info when
  it is run inside LOCK TABLES.
  
  Affects MyISAM only.

  include/my_base.h@stripped, 2006-11-09 15:55:26+04:00, svoj@stripped +5 -0
    Added HA_STATUS_FROM_SHARE flag, that instruct handler to read state
    info from share not performing a lock.

  myisam/mi_info.c@stripped, 2006-11-09 15:55:26+04:00, svoj@stripped +10 -8
    In case HA_STATUS_FROM_SHARE is set, read state info from myisam share.

  sql/sql_show.cc@stripped, 2006-11-09 15:55:26+04:00, svoj@stripped +1 -1
    Get state info from share, which is likely more recent than
    local handler copy of the state.

# 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:	april.(none)
# Root:	/home/svoj/devel/mysql/BUG23526/mysql-5.0-engines

--- 1.81/include/my_base.h	2006-11-09 15:55:32 +04:00
+++ 1.82/include/my_base.h	2006-11-09 15:55:32 +04:00
@@ -316,6 +316,11 @@ enum ha_base_keytype {
   update handler::auto_increment_value
 */
 #define HA_STATUS_AUTO          64
+/*
+  in case local copy of the 'info' is likely outdated, read it from the share.
+*/
+#define HA_STATUS_FROM_SHARE 128
+
 
 	/* Errorcodes given by functions */
 

--- 1.15/myisam/mi_info.c	2006-11-09 15:55:32 +04:00
+++ 1.16/myisam/mi_info.c	2006-11-09 15:55:32 +04:00
@@ -50,17 +50,19 @@ int mi_status(MI_INFO *info, register MI
   }
   if (flag & HA_STATUS_VARIABLE)
   {
-    x->records	 	= info->state->records;
-    x->deleted	 	= info->state->del;
-    x->delete_length	= info->state->empty;
-    x->data_file_length	=info->state->data_file_length;
-    x->index_file_length=info->state->key_file_length;
+    MI_STATUS_INFO *state= (flag & HA_STATUS_FROM_SHARE) ? &share->state.state
:
+                           info->state;
+    x->records= state->records;
+    x->deleted= state->del;
+    x->delete_length= state->empty;
+    x->data_file_length= state->data_file_length;
+    x->index_file_length= state->key_file_length;
 
     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= state->records ?
+                       (ulong) ((x->data_file_length - x->delete_length) /
+                       x->records) : (ulong) share->min_pack_length;
   }
   if (flag & HA_STATUS_ERRKEY)
   {

--- 1.329/sql/sql_show.cc	2006-11-09 15:55:32 +04:00
+++ 1.330/sql/sql_show.cc	2006-11-09 15:55:32 +04:00
@@ -2444,7 +2444,7 @@ static int get_schema_tables_record(THD 
     handler *file= show_table->file;
 
     file->info(HA_STATUS_VARIABLE | HA_STATUS_TIME | HA_STATUS_AUTO |
-               HA_STATUS_NO_LOCK);
+               HA_STATUS_NO_LOCK | HA_STATUS_FROM_SHARE);
     if (share->tmp_table == SYSTEM_TMP_TABLE)
       table->field[3]->store(STRING_WITH_LEN("SYSTEM VIEW"), cs);
     else if (share->tmp_table)