bk commit into 4.1 tree (stewart:1.2483) BUG#19914

[Stewart Smith]

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ChangeSet
  1.2483 06/05/24 00:06:32 stewart@stripped +2 -0
  BUG#19914 SELECT COUNT(*) sometimes returns MAX_INT on cluster tables
  
  The optimizer can use the handler::info function for a quick COUNT(*) if
  the handler says it can do exact count.
  
  But, for NDB, ::info can fail (as it talks to the cluster). Check for error and
  try an alternative method.
  
  See comments in the bug for more details.

  sql/opt_sum.cc
    1.46 06/05/24 00:06:26 stewart@stripped +15 -1
    With NDB, ha_ndbcluster::info may have an error condition when getting the
    exact count.
    
    Handle this and try alternative methods to get a row count. These are less
    efficient, so we should first try to use ::info.

  sql/ha_ndbcluster.cc
    1.181 06/05/24 00:06:26 stewart@stripped +4 -1
    If there was an error getting the table statistics, say we had an error by
    setting m_ha_not_exact_count.
    
    This is just per-handler, so eventually we'll retry getting the exact count
    from NDB the quick way.

# 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:	stewart
# Host:	willster.(none)
# Root:	/home/stewart/Documents/MySQL/4.1/bug19914

--- 1.45/sql/opt_sum.cc	2005-09-26 04:22:20 +10:00
+++ 1.46/sql/opt_sum.cc	2006-05-24 00:06:26 +10:00
@@ -126,7 +126,21 @@
     else
     {
       tl->table->file->info(HA_STATUS_VARIABLE | HA_STATUS_NO_LOCK);
-      count*= tl->table->file->records;
+      /*
+        Since handler::info is void and not int, error notification for
+        an error on getting exact count is reported back by setting
+        the HA_NOT_EXACT_COUNT table_flag.
+
+        Optimiser can then try a different method to get the count.
+        You may then get a better error message.
+       */
+      if(tl->table->file->table_flags() & HA_NOT_EXACT_COUNT)
+      {
+        is_exact_count= FALSE;
+        count= 1;
+      }
+      else
+        count*= tl->table->file->records;
     }
   }
 

--- 1.180/sql/ha_ndbcluster.cc	2006-05-16 00:23:54 +10:00
+++ 1.181/sql/ha_ndbcluster.cc	2006-05-24 00:06:26 +10:00
@@ -273,6 +273,8 @@
     if(ndb_get_table_statistics(ndb, m_tabname, &rows, 0) == 0){
       info->records= rows;
     }
+    else
+      m_ha_not_exact_count= true;
   }
   {
     THD *thd= current_thd;
@@ -2820,7 +2822,8 @@
       Ndb *ndb= get_ndb();
       Uint64 rows= 100;
       if (current_thd->variables.ndb_use_exact_count)
-	ndb_get_table_statistics(ndb, m_tabname, &rows, 0);
+	if(ndb_get_table_statistics(ndb, m_tabname, &rows, 0)<0)
+          m_ha_not_exact_count= true;
       records= rows;
     }
   }