BUG#18160 - Memory-/HEAP Table endless growing indexes

Updating data in HEAP table with BTREE index results in wrong index_length
counter value, which keeps growing after each update.

When inserting new record into tree counter is incremented by:
sizeof(TREE_ELEMENT) + key_size + tree->size_of_element
But when deleting element from tree it doesn't decrement counter by key_size:
sizeof(TREE_ELEMENT) + tree->size_of_element

This fix makes accurate allocated memory counter for tree. That is
decrease counter by key_size when deleting tree element.


heap/hp_delete.c:
  Added size of the key to tree_delete() for accurate allocated memory counter.
include/my_tree.h:
  Added size of the key to tree_delete() for accurate allocated memory counter.
myisam/myisamlog.c:
  Added size of the key to tree_delete() for accurate allocated memory counter.
mysql-test/r/heap_btree.result:
  Testcase for BUG#18160.
mysql-test/t/heap_btree.test:
  Testcase for BUG#18160.
mysys/tree.c:
  Added size of the key to tree_delete() for accurate allocated memory counter.
  Note that this size is optional. If one doesn't need precise counter it is safe
  to pass 0 as key_size.

1 files changed, 10 insertions, 0 deletions

diff --git a/mysql-test/r/heap_btree.result b/mysql-test/r/heap_btree.result
index 374d2c63632..b63eaf7e48c 100644
--- a/mysql-test/r/heap_btree.result
+++ b/mysql-test/r/heap_btree.result
@@ -246,3 +246,13 @@ DELETE from t1 where a < 100;
 SELECT * from t1;
 a
 DROP TABLE t1;
+CREATE TABLE t1(val INT, KEY USING BTREE(val)) ENGINE=memory;
+INSERT INTO t1 VALUES(0);
+SELECT INDEX_LENGTH FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME='t1';
+INDEX_LENGTH
+21
+UPDATE t1 SET val=1;
+SELECT INDEX_LENGTH FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_SCHEMA=DATABASE() AND TABLE_NAME='t1';
+INDEX_LENGTH
+21
+DROP TABLE t1;