safety first - tell mariadb client not to execute dangerous
cli commands, they cannot be present in the dump anyway.
wrapping the command in /*!999999 ..... */ guarantees that
if a non-mariadb-cli client loads the dump and sends it to the
server - the server will ignore the command it doesn't understand
This bug led to wrong result sets returned by the second execution of
prepared statements from selects using mergeable derived tables pushed
into external engine. Such derived tables are always materialized. The
decision that they have to be materialized is taken late in the function
mysql_derived_optimized(). For regular derived tables this decision is
usually taken at the prepare phase. However in some cases for some derived
tables this decision is made in mysql_derived_optimized() too. It can be
seen in the code of mysql_derived_fill() that for such a derived table it's
critical to change its translation table to tune it to the fields of the
temporary table used for materialization of the derived table and this
must be done after each refill of the derived table. The same actions are
needed for derived tables pushed into external engines.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
This patch adds for "--ps-protocol" second execution
of queries "SELECT".
Also in this patch it is added ability to disable/enable
(--disable_ps2_protocol/--enable_ps2_protocol) second
execution for "--ps-prototocol" in testcases.
ANALYZE FORMAT=JSON output now includes table.r_engine_stats which
has the engine statistics. Only non-zero members are printed.
Internally: EXPLAIN data structures Explain_table_acccess and
Explain_update now have handler* handler_for_stats pointer.
It is used to read statistics from handler_for_stats->handler_stats.
The following applies only to 10.9+, backport doesn't use it:
Explain data structures exist after the tables are closed. We avoid
walking invalid pointers using this:
- SQL layer calls Explain_query::notify_tables_are_closed() before
closing tables.
- After that call, printing of JSON output is disabled. Non-JSON output
can be printed but we don't access handler_for_stats when doing that.
There was no actual execution of the SQL of a pushed derived table,
which caused "r_rows" to be always displayed as 0 and "r_total_time_ms"
to show inaccurate numbers.
This commit makes a derived table SQL to be executed by the storage
engine, so the server is able to calculate the number of rows returned
and measure the execution time more accurately
The problem was that federated engine does not support comparable rowids
which was not taken into account by semijoin code.
Fixed by checking that we don't use semijoin with tables that does not
support comparable rowids.
Other things:
- Fixed some typos in the code comments
Deallocation of TABLE_LIST::dt_handler and TABLE_LIST::pushdown_derived
was performed in multiple places if code. This not only made the code
more difficult to maintain but also led to memory leaks and
ASAN heap-use-after-free errors.
This commit puts deallocation of TABLE_LIST::dt_handler and
TABLE_LIST::pushdown_derived to the single point - JOIN::cleanup()
FederatedX table may refer to a table with a different name on the
remote server:
test> CREATE TABLE t2 (...) ENGINE="FEDERATEDX"
CONNECTION="mysql://user:pass@192.168.1.111:9308/federatedx/t1";
test> select * from t2 where ...;
This could cause an issue with federated_pushdown=1, because FederatedX
pushes the query (or derived table's) text to the remote server. The remote
server will try to read from table t2 (while it should read from t1).
Solution: do not allow pushing down queries with tables that have different
db_name.table name on the local and remote server.
This patch also fixes:
MDEV-29863 Server crashes in federatedx_txn::acquire after select from the
FederatedX table with partitions
Solution: disallow pushdown when partitioned FederatedX tables are used.
