bk commit into 5.1 tree (sergefp:1.2231) BUG#14940

[Sergey Petrunia]

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

ChangeSet@stripped, 2006-07-30 00:02:09+04:00, sergefp@stripped +1 -0
  BUG#14940: post-review fixes

  sql/opt_range.cc@stripped, 2006-07-30 00:02:06+04:00, sergefp@stripped +8 -6
    BUG#14940: post-review fixes:
     - fix comments
     - use set_if_smaller

# 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:	sergefp
# Host:	newbox.mylan
# Root:	/home/psergey/mysql-5.1-bug14940-r4

--- 1.224/sql/opt_range.cc	2006-07-30 00:02:14 +04:00
+++ 1.225/sql/opt_range.cc	2006-07-30 00:02:14 +04:00
@@ -1872,14 +1872,17 @@
     correlations between sets of rows they will return.
     
     For example, if values of tbl.key1 and tbl.key2 are independent (a right
-    assumption if we have no infromation about their correlation) then the
+    assumption if we have no information about their correlation) then the
     correct estimate will be:
     
       E(#rows("tbl.key1 < c1 AND tbl.key2 < c2")) = 
-      = E(#rows(tbl.key1 < c1)) / total_rows(tbl) * E(#rows(tbl.key2 < c2) / 
-        total_rows(tbl).
+      = E(#rows(tbl.key1 < c1)) / total_rows(tbl) * E(#rows(tbl.key2 < c2)
 
-    which is smaller than MIN(rows(tbl.key1 < c1), rows(tbl.key2 < c2)).
+    which is smaller than 
+      
+       MIN(E(#rows(tbl.key1 < c1), E(#rows(tbl.key2 < c2)))
+
+    which is currently produced.
 
   TODO
    * Change the value returned in quick_condition_rows from a pessimistic
@@ -4469,8 +4472,7 @@
   trp->read_cost= total_cost;
   trp->records= records;
   trp->cpk_scan= NULL;
-  if (records < param->table->quick_condition_rows)
-     param->table->quick_condition_rows= records;
+  set_if_smaller(param->table->quick_condition_rows, records); 
 
   DBUG_PRINT("info",
              ("Returning covering ROR-intersect plan: cost %g, records %lu",