When allocate_block() have failed Query_cache::insert_table() misses
to init node->parent which is then accessed with outdated data. There
is check in Query_cache::register_all_tables():
if (block_table->parent)
unlink_table(block_table);
So unlink_table() is avoided when parent is 0.
Synopsis: If SELECT returned answer from Query Cache it is not really executed.
The reason for firing of assertion
DBUG_ASSERT((mem_root->flags & ROOT_FLAG_READ_ONLY) == 0);
is that in case the query_cache is on and the same query run by different
stored routines the following use case can take place:
First, lets say that bodies of routines used by the test case are the same
and contains the only query 'SELECT * FROM t1';
call p1() -- a result set is stored in query cache for further use.
call p2() -- the same query is run against the table t1, that result in
not running the actual query but using its cached result.
On finishing execution of this routine, its memory root is
marked for read only since every SP instruction that this
routine contains has been executed.
INSERT INT t1 VALUE (1); -- force following invalidation of query cache
call p2() -- query the table t1 will result in assertion failure since its
execution would require allocation on the memory root that
has been already marked as read only memory root
The root cause of firing the assertion is that memory root of the stored
routine 'p2' was marked as read only although actual execution of the query
contained inside hadn't been performed.
To fix the issue, mark a SP instruction as not yet run in case its execution
doesn't result in real query processing and a result set got from query cache
instead.
Note that, this issue relates server built in debug mode AND with the protect
statement memory root feature turned on. It doesn't affect server built
in release mode.
This was done after discussions with Igor, Sanja and Bar.
The main reason for removing the deprication was to ensure that MariaDB
is always backward compatible whenever possible.
Other things:
- Added statistics counters, mainly for the feedback plugin.
- INTO OUTFILE
- INTO variable
- If INTO is using the old syntax (end of query)
Withing this task the following changes were made:
- Added sending of metadata info in prepare phase for the admin related
command (check table, checksum table, repair, optimize, analyze).
- Refactored implmentation of HELP command to support its execution in
PS mode
- Added support for execution of LOAD INTO and XA- related statements
in PS mode
- Modified mysqltest.cc to run statements in PS mode unconditionally
in case the option --ps-protocol is set. Formerly, only those statements
were executed using PS protocol that matched the hard-coded regular expression
- Fixed the following issues:
The statement
explain select (select 2)
executed in regular and PS mode produces different results:
MariaDB [test]> prepare stmt from "explain select (select 2)";
Query OK, 0 rows affected (0,000 sec)
Statement prepared
MariaDB [test]> execute stmt;
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
| 1 | PRIMARY | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
| 2 | SUBQUERY | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
2 rows in set (0,000 sec)
MariaDB [test]> explain select (select 2);
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
| 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
1 row in set, 1 warning (0,000 sec)
In case the statement
CREATE TABLE t1 SELECT * FROM (SELECT 1 AS a, (SELECT a+0)) a
is run in PS mode it fails with the error
ERROR 1054 (42S22): Unknown column 'a' in 'field list'.
- Uniform handling of read-only variables both in case the SET var=val
statement is executed as regular or prepared statememt.
- Fixed assertion firing on handling LOAD DATA statement for temporary tables
- Relaxed assert condition in the function lex_end_stage1() by adding
the commands SQLCOM_ALTER_EVENT, SQLCOM_CREATE_PACKAGE,
SQLCOM_CREATE_PACKAGE_BODY to a list of supported command
- Removed raising of the error ER_UNSUPPORTED_PS in the function
check_prepared_statement() for the ALTER VIEW command
- Added initialization of the data memember st_select_lex_unit::last_procedure
(assign NULL value) in the constructor
Without this change the test case main.ctype_utf8 fails with the following
report in case it is run with the optoin --ps-protocol.
mysqltest: At line 2278: query 'VALUES (_latin1 0xDF) UNION VALUES(_utf8'a' COLLATE utf8_bin)' failed: 2013: Lost connection
- The following bug reports were fixed:
MDEV-24460: Multiple rows result set returned from stored
routine over prepared statement binary protocol is
handled incorrectly
CONC-519: mariadb client library doesn't handle server_status and
warnign_count fields received in the packet
COM_STMT_EXECUTE_RESPONSE.
Reasons for these bug reports have the same nature and caused by
missing loop iteration on results sent by server in response to
COM_STMT_EXECUTE packet.
Enclosing of statements for processing of COM_STMT_EXECUTE response
in the construct like
do
{
...
} while (!mysql_stmt_next_result());
fixes the above mentioned bug reports.
