=== modified file 'sql/sql_select.cc'
--- sql/sql_select.cc	2013-03-29 02:18:36 +0000
+++ sql/sql_select.cc	2013-03-31 22:59:12 +0000
@@ -1041,6 +1041,24 @@ JOIN::optimize()
       MEMROOT for prepared statements and stored procedures.
     */
 
+    if (!thd->lex->describe &&
+        conds &&
+        select_lex &&
+        select_lex->table_list.first &&
+        select_lex->table_list.first->table &&
+        conds->used_tables() &&
+        conds->used_tables() == select_lex->table_list.first->table->map &&
+        select_lex->table_list.first->table->s->tmp_table != NO_TMP_TABLE &&
+        select_lex->table_list.first->derived == 0 &&
+        select_lex->table_list.first->view == 0)
+    {
+      COND_STATISTIC cond= {conds, 0};
+      List<COND_STATISTIC> li;
+      li.push_back(&cond);
+      check_selectivity(thd, 10, select_lex->table_list.first->table, &li);
+      li.empty();
+    }
+
     Query_arena *arena= thd->stmt_arena, backup;
     if (arena->is_conventional())
       arena= 0;                                   // For easier test
@@ -23398,6 +23416,78 @@ uint get_index_for_order(ORDER *order, T
   return MAX_KEY;
 }
 
+/*
+  Count how much times conditions are true for several first rows of the table
+
+  @param thd             thread handle
+  @param rows_to_read    how much rows to check
+  @param table           table which should be checked
+  @conds conds           list of conditions and countars for them
+
+  @return number of really checked rows or 0 in case of error or empty table
+*/
+
+ulong check_selectivity(THD *thd,
+                        ulong rows_to_read,
+                        TABLE *table,
+                        List<COND_STATISTIC> *conds)
+{
+  ulong count= 0;
+  COND_STATISTIC *cond;
+  List_iterator_fast<COND_STATISTIC> it(*conds);
+  handler *file= table->file;
+  uchar *record= table->record[0];
+  int error= 0;
+  DBUG_ENTER("check_selectivity");
+
+  DBUG_ASSERT(rows_to_read > 0);
+  while ((cond= it++))
+  {
+    DBUG_ASSERT(cond->cond);
+    DBUG_ASSERT(cond->cond->used_tables() == table->map);
+    cond->positive= 0;
+  }
+  it.rewind();
+
+  if (file->ha_rnd_init_with_error(1))
+    DBUG_RETURN(0);
+  do
+  {
+    error= file->ha_rnd_next(record);
+
+    if (thd->killed)
+    {
+      thd->send_kill_message();
+      count= 0;
+      goto err;
+    }
+    if (error)
+    {
+      if (error == HA_ERR_RECORD_DELETED)
+        continue;
+      if (error == HA_ERR_END_OF_FILE)
+	break;
+      goto err;
+    }
+
+    count++;
+    while ((cond= it++))
+    {
+      if (cond->cond->val_bool())
+        cond->positive++;
+    }
+    it.rewind();
+
+  } while (count < rows_to_read);
+
+  file->ha_rnd_end();
+  DBUG_RETURN(count);
+
+err:
+  DBUG_PRINT("error", ("error %d", error));
+  file->ha_rnd_end();
+  DBUG_RETURN(0);
+}
 
 /**
   @} (end of group Query_Optimizer)

=== modified file 'sql/sql_select.h'
--- sql/sql_select.h	2013-02-28 21:47:29 +0000
+++ sql/sql_select.h	2013-03-31 22:13:35 +0000
@@ -1823,4 +1823,16 @@ void setup_tmp_table_column_bitmaps(TABL
 double prev_record_reads(POSITION *positions, uint idx, table_map found_ref);
 void fix_list_after_tbl_changes(SELECT_LEX *new_parent, List<TABLE_LIST> *tlist);
 
+struct st_cond_statistic
+{
+  Item *cond;
+  ulong positive;
+};
+typedef struct st_cond_statistic COND_STATISTIC;
+
+ulong check_selectivity(THD *thd,
+                        ulong rows_to_read,
+                        TABLE *table,
+                        List<COND_STATISTIC> *conds);
+
 #endif /* SQL_SELECT_INCLUDED */