d0a872c...
by
Dmitry Shulga <email address hidden>
MDEV-14959: Fixed memory leak relating with view and IS
Fixed memory leak taken place on executing a prepared statement or
a stored routine that querying a view and this view constructed
on an information schema table. For example,
Lets consider the following definition of the view 'v1'
CREATE VIEW v1 AS SELECT table_name FROM information_schema.views
ORDER BY table_name;
Querying this view in PS mode result in hit of assert.
PREPARE stmt FROM "SELECT * FROM v1";
EXECUTE stmt;
EXECUTE stmt; (*)
Running the statement marked with (*) leads to a crash in case
server build with mode to control allocation of a memory from SP/PS
memory root on the second and following executions of PS/SP.
The reason of leaking the memory is that a memory allocated on
processing of FRM file for the view requested from a PS/PS memory
root meaning that this memory be released only when a stored routine
be evicted from SP-cache or a prepared statement be deallocated
that typically happens on termination of a user session.
To fix the issue switch to a memory root specially created for
allocation of short-lived objects that requested on parsing FRM.
be02356...
by
Dmitry Shulga <email address hidden>
MDEV-14959: Fixed memory leak happened on re-parsing a view that substitutes a table
In case a table accessed by a PS/SP is dropped after the first execution of
PS/SP and a view created with the same name as a table just dropped then
the second execution of PS/SP leads to allocation of a memory on SP/PS
memory root already marked as read only on first execution.
For example, the following test case:
CREATE TABLE t1 (a INT);
PREPARE stmt FROM "INSERT INTO t1 VALUES (1)";
EXECUTE stmt;
DROP TABLE t1;
CREATE VIEW t1 S SELECT 1;
--error ER_NON_INSERTABLE_TABLE
EXECUTE stmt; # (*)
DROP VIEW t1;
will hit assert on running the statement 'EXECUTE stmt' marked with (*)
when allocation of a memory be performed on parsing the view.
Memory allocation is requested inside the function mysql_make_view
when a view definition being parsed. In order to avoid an assertion
failure, call of the function mysql_make_view() must be moved after
invocation of the function check_and_update_table_version().
It will result in re-preparing the whole PS statement or current
SP instruction that will free currently allocated items and reset
read_only flag for the memory root.
