handle tree overflow in count(distinct)

test heap table/tree overflow in count(distinct)


mysql-test/r/count_distinct2.result:
  added test for tree/heap table overflow
mysql-test/t/count_distinct2.test:
  test tree/heap table overflow
sql/item_sum.cc:
  handle tree overflow in count(distinct)
sql/item_sum.h:
  t

1 files changed, 29 insertions, 0 deletions

diff --git a/mysql-test/t/count_distinct2.test b/mysql-test/t/count_distinct2.test
index 5ddd96198fe..2447a7c3611 100644
--- a/mysql-test/t/count_distinct2.test
+++ b/mysql-test/t/count_distinct2.test
@@ -43,3 +43,32 @@ select count(distinct n1), count(distinct n2) from t1;
 
 select count(distinct n2), n1 from t1 group by n1;
 drop table t1;
+
+# test the converstion from tree to MyISAM
+create table t1 (n int);
+let $1=5000;
+while ($1)
+{
+ eval insert into t1 values($1);
+ dec $1;
+}
+
+flush status;
+select count(distinct n) from t1;
+show status like 'Created_tmp_disk_tables';
+drop table t1;
+
+#test conversion from heap to MyISAM
+create table t1 (s text);
+let $1=5000;
+while ($1)
+{
+ eval insert into t1 values('$1');
+ dec $1;
+}
+
+flush status;
+select count(distinct s) from t1;
+show status like 'Created_tmp_disk_tables';
+drop table t1;
+