bk commit into 4.1 tree (istruewing:1.2560) BUG#12240

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ChangeSet@stripped, 2006-10-11 09:52:53+02:00, istruewing@stripped +1 -0
  Bug#12240 - Rows Examined in Slow Log showing incorrect number?
  
  Examined rows are counted for every join part. The per-join-part
  counter was incremented over all iterations. The result variable
  was replaced at the end of every iteration. The final result was
  the number of examined rows by the join part that ended its
  execution as the last one. The numbers of other join parts was
  lost.
  
  Now we reset the per-join-part counter before every iteration and
  add it to the result variable at the end of the iteration. That
  way we get the sum of all iterations of all join parts.

  sql/sql_select.cc@stripped, 2006-10-11 09:52:50+02:00, istruewing@stripped +18 -6
    Bug#12240 - Rows Examined in Slow Log showing incorrect number?
    Fixed reseting and accumulation of examined rows counts.

# 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:	istruewing
# Host:	chilla.local
# Root:	/home/mydev/mysql-4.1-bug12240

--- 1.459/sql/sql_select.cc	2006-10-11 09:52:57 +02:00
+++ 1.460/sql/sql_select.cc	2006-10-11 09:52:57 +02:00
@@ -1171,12 +1171,13 @@ JOIN::exec()
     thd->examined_row_count= 0;
     DBUG_VOID_RETURN;
   }
-  /* 
-    don't reset the found rows count if there're no tables
-    as FOUND_ROWS() may be called.
-  */  
+  /*
+    Don't reset the found rows count if there're no tables as
+    FOUND_ROWS() may be called. Never reset the examined row count here.
+    It must be accumulated from all join iterations of all join parts.
+  */
   if (tables)
-    thd->limit_found_rows= thd->examined_row_count= 0;
+    thd->limit_found_rows= 0;
 
   if (zero_result_cause)
   {
@@ -1224,6 +1225,12 @@ JOIN::exec()
   List<Item> *curr_all_fields= &all_fields;
   List<Item> *curr_fields_list= &fields_list;
   TABLE *curr_tmp_table= 0;
+  /*
+    Initialize examined rows here because the values from all join parts
+    must be accumulated in examined_row_count. Hence every join
+    iteration must count from zero.
+  */
+  curr_join->examined_rows= 0;
 
   /* Create a tmp table if distinct or if the sort is too complicated */
   if (need_tmp)
@@ -1572,7 +1579,10 @@ JOIN::exec()
   error= thd->net.report_error ? -1 :
     do_select(curr_join, curr_fields_list, NULL, procedure);
   thd->limit_found_rows= curr_join->send_records;
-  thd->examined_row_count= curr_join->examined_rows;
+  /* Accumulate the counts from all join iterations of all join parts. */
+  thd->examined_row_count+= curr_join->examined_rows;
+  DBUG_PRINT("counts", ("thd->examined_row_count: %lu",
+                        (ulong) thd->examined_row_count));
   DBUG_VOID_RETURN;
 }
 
@@ -6179,6 +6189,8 @@ sub_select(JOIN *join,JOIN_TAB *join_tab
 	return -2;				/* purecov: inspected */
       }
       join->examined_rows++;
+      DBUG_PRINT("counts", ("join->examined_rows++: %lu",
+                            (ulong) join->examined_rows));
       join->thd->row_count++;
       if (!on_expr || on_expr->val_int())
       {