For each SELECT the list sj_nests is built by the
function simplify_joins() when scanning different
join nests. This function may be called several
times for the same join nest. That's why before
adding a new member to sj_nests it is necessary
to check if it's already in the list.
The code of simplify_joins() lacked this check and
as a result it could cause memory overwright for
some queries.

             in buildbot

Removed plugin_array_version: it is being checked without mutex protection and
thus is prone to data race and race conditions. In effect plugins are not
protected from concurrent destruction.

Removed state_mask inversion: doesn't seem to make any sense.

When collecting local plugins list, only add plugins that match state_mask.

Use plugin ref counting to protect against concurrent plugin destruction.

MDEV-9208: Function->Function->View = Mysqld segfault (Server crashes in Dependency_marker::visit_field on 2nd execution with merged subquery)

Prevent crossing name resolution border in finding item tables.

MDEV-13595: mariadb-10.2.8/storage/maria/ma_loghandler.c:2730]: (style) Array index 'chunk_offset' is used before limits check.

In fact just a cosmetic fix, code was safe because translog_get_first_chunk_offset return offsets inside the page.

btr_cur_pessimistic_delete(): Discard a possible record lock also in
the case when the record was the only one in the page. Failure to
do this would corrupt the record lock data structures in a partial
rollback (ROLLBACK TO SAVEPOINT or rolling back a row operation due
to some error, such as a duplicate key in a unique secondary index).

        The MySQL 5.6 doesn't always send the MYSQL_AUDIT_GENERAL_LOG
        notification. So we have to suppress the log_current_query()
        in this case.

MDEV-11240: Server crashes in check_view_single_update or Assertion `derived->table' failed in mysql_derived_merge_for_insert

Before "merge" view shoud be inited to maintaing transitive attributes like "multitable".

The test wasn't restoring log_output properly.
Also added output of query_time in case of wrong result, to
investigate the failure described in MDEV-13408

MDEV-13458: Wrong result for aggregate function with distinct clause when the value for tmp_table_size is small

Fixed by making sure that the sort buffer would have atleast MERGEBUFF2 keys.
Also fixed MDEV-13457 by making sure that an empty tree is never dumped to the disk

Problem
rpl.rpl_mdev-11092 fails in buildbot because after starting slave in
wait_for_slave_sql_error_and_skip.inc slave is started but there may be
chances that we have not skipped the last error and Last_SQL_Errno is
still not zero untill the end of rpl_end.inc , which will compare
Last_SQL_Errno to 0. So in this this case rpl_mdev-11092 fails.

Solution
After starting slave in wait_for_slave_sql_error_and_skip.inc we will wait for
Last_SQL_Errno to become 0.

Inspired by: https://github.com/devexp-db/mariadb/blob/f27/mariadb-covscan-stroverflow.patch

Signed-off-by: Daniel Black <daniel.black@au.ibm.com>

test case

simplify.
add a test case.

MDEV-11240: Server crashes in check_view_single_update or Assertion `derived->table' failed in mysql_derived_merge_for_insert

Move table pointer for single table view (even if it is view over other view) to make the access universal.

        Set name_length properly in Item_idnet constructors.

end_io_call uses uninitialized values from the new_data_cache

As such we the buffer 0 and check this before calling end_io_cache on it.

Thanks Sergey Vojtovich for the review and for this solution.

Found by Coverity (ref 972481).

A few tests assumes that the CYCLE timer is always available,
which is not true on some platforms (e.g. ARM).
Fixing the tests not to reply on the CYCLE availability.

in ab785bfe

Coverity report this as:
CID 971840 (#1 of 1): Operands don't affect result (CONSTANT_EXPRESSION_RESULT)
result_independent_of_operands: 4 | (flags & 1) is always true regardless of the values of its operands. This occurs as the logical first operand of "?:".

The C order of precidence has | of higher precidence than ?:. The
intenting implies an | of the 3 terms.

Adjust to intented meaning.

Avoid using STDERR_FILENO. The server uses freopen(stderr),
so stderr can be on any file descriptor.

field_names[x][y] is a pointer

client/mysql.cc: In function 'void build_completion_hash(bool, bool)':
client/mysql.cc:2855:37: error: invalid conversion from 'char' to 'char*' [-fpermissive]
       field_names[i][num_fields*2]= '\0';
Signed-off-by: Daniel Black <daniel.black@au.ibm.com>

Same MDEV, second bug.
Merge buffer must fit at least MERGEBUFF2 (that is, 15) key values.
Because merge_index() can merge that many buffers, and
merge_many_buff() leaves that many buffers unmerged.

use the correct value for the merge_buffer size, max_in_memory_size
is too small and merge_walk() fails.

also: remove a cast.

already fixed by be55bbc2
just add a test case

only compare field references with an alias (from the SELECT clause)
when this reference doesn't specify an explicit table name part.