It was meaningful only for one-thread-per-connection scheduler anyway,
so call init_new_connection_handler_thread() directly from
handle_one_connection().

It was somewhat harmful for no-threads scheduler, because it'd attempt to
detach main thread on AIX_3_2 and Siemens unix (and DEC OSF/1 3.2 too).
Also it does duplicate my_thread_init() call, which may produce a warning
under EXTRA_DEBUG_THREADS.

start_wsrep_THD() shouldn't have called it at all: it already detached
and called my_thread_init().

Part of MDEV-19515 - Improve connect speed

Gives ~10% throughput improvemet in sysbench connect benchmark.

Part of MDEV-19515 - Improve connect speed

Gives ~3% throughput improvemet in sysbench connect benchmark.

Part of MDEV-19515 - Improve connect speed

Rather than iterating global plugin collection, iterate THD local
collection. Removes two LOCK_plugin locks per connection.

Part of MDEV-19515 - Improve connect speed

Part of MDEV-19515 - Improve connect speed

Use thd_get_ha_data()/thd_set_ha_data() which protect against plugin
removal until it has THD ha_data.

Do not reset THD ha_data in rocksdb_close_connection(), cleaner approach
is to let ha_close_connection() do it.

Removed transaction objects cleanup from rocksdb_done_func(). As we lock
plugin properly, there must be no transaction objects during RocksDB
shutdown.

Part of MDEV-19515 - Improve connect speed

Part of MDEV-19515 - Improve connect speed

Use thd_get_ha_data()/thd_set_ha_data() which protect against plugin
removal until it has THD ha_data.

Part of MDEV-19515 - Improve connect speed

Use thd_get_ha_data()/thd_set_ha_data() which protect against plugin
removal until it has THD ha_data.

Do not reset THD ha_data in sphinx_close_connection(), cleaner approach
is to let ha_close_connection() do it.

Part of MDEV-19515 - Improve connect speed

Use thd_get_ha_data()/thd_set_ha_data() which protect against plugin
removal until it has THD ha_data.

Do not reset THD ha_data in mrn_close_connection(), cleaner approach
is to let ha_close_connection() do it.

Part of MDEV-19515 - Improve connect speed

Do not reset THD ha_data in spider_close_connection(), cleaner approach
is to let ha_close_connection() do it.

Part of MDEV-19515 - Improve connect speed

Use thd_get_ha_data()/thd_set_ha_data() which protect against plugin
removal until it has THD ha_data.

Do not reset THD ha_data in ha_federatedx::disconnect(), cleaner approach
is to let ha_close_connection() do it.

Part of MDEV-19515 - Improve connect speed

Part of MDEV-19515 - Improve connect speed

It was wrong anyway, as it may not get updated by the time created thread
reads it. And it was 0 for cached threads.

Part of MDEV-19515 - Improve connect speed

Part of MDEV-19515 - Improve connect speed

Part of MDEV-19515 - Improve connect speed

It may be beneficial for slow-path, where new thread is to be created.
However it is harmful for fast-path, where thread cache can fulfil
request: it caused 2 extra loads of write-contended variables.

Also shrink variables scope.

Part of MDEV-19515 - Improve connect speed

Removed FD_CLOEXEC setting: already done by mysql_socket_accept().

Moved O_NONBLOCK setting out of accepting loop.

Removed blocking acceptance attempt, which was dead code. It was supposed
to be executed before the last iteration, however it was actually executed
during the last iteration. And it is not correct to block on one socket
leaving other sockets unattended anyway.

Gives ~5% throughput improvemet in sysbench connect benchmark.

Part of MDEV-19515 - Improve connect speed

Part of MDEV-19515 - Improve connect speed

Part of MDEV-19515 - Improve connect speed

abort_loop is intended to break accepting connections loop in main thread,
however it is being used for other purposes.

cache_thread() is governed by kill_cached_threads, no need to check
abort_loop here.

Check in create_new_thread() is redundant, abort_loop already checked
by caller.

Part of MDEV-19515 - Improve connect speed

This commit adds a new feature to the server to add comments at the database
level. 1024 bytes is the maximum comment length allowed. If the comment length
exceeds this limit, a new error/warning code 4144 is thrown, based on whether
thd->is_strict_mode() is true/false. The database comment is also added to the
db.opt file, as well as to the information_schema.schemata table.

Make sure that SIGNALs are not overwritten before they
are received.

Use different signal names, so that subsequent WAIT_FOR is not awaken by
previous signal.

MDEV-19277: Add status variable that gets incremented if connection is aborted prior to authentication
MDEV-19282: Log more specific warning with log_warnings=2 if connection is aborted prior to authentication

In 62d28f83 the CMake variable
IS_BIG_ENDIAN became orphaned. Remove it.

In wsrep_plugins_post_init we iterate all theads and if they are
galera appliers (wsrep_applier) we init session variables. However,
current_thd was not set and recent changes on session variables
require holding LOCK_gloal_system_variables mutex.

This is 10.4 version.

With MDEV-19384 fixed FTWRL releases HANDLER locks early, which allows
concurrent threads to go. Test case may get stuck on FTWRL waiting for
LOCK TABLES.

- Remove warning about aria_control_file
- Write to unique test file

Other things:
- Fixed typo in aria_chk --help

So to push index condition for each join tab we have calculate the index condition that can be pushed and then
remove this index condition from the original condition. This is done through the function make_cond_remainder.
The problem is the function make_cond_remainder does not remove index condition when there is an OR operator.

Fixed this by making the function make_cond_remainder to keep in mind of the OR operator.
Also updated results for multiple test files which were incorrectly updated by the commit e0c1b3f2

code which was supposed to remove the condition present in the index
condition was not getting executed when the condition had OR operator, with AND the pushed
index condition was getting removed from where.

This problem affects all versions starting from 5.5 but this is a performance improvement, so fixing it in 10.4

Problem was that SHOW CREATE didn't remove PAGE_CHECKSUM=1

Signed-off-by: hygonsoc <hygonsoc@gmail.com>

For a table column `a`, the above expressions logically
equate to false in all cases.

With this patch the optimizer knows about this and queries
like:

SELECT * FROM t1 WHERE a!=a

no longer need to evaluate a!=a for every row.

The same applies if the expression was `a<a`, or `a>a`

An `EXPLAIN SELECT COOUNT(*) FROM t1 WHERE a<a` will show:

id     select_type     table   type    possible_keys   key     key_len ref     rows    Extra
1      SIMPLE  NULL    NULL    NULL    NULL    NULL    NULL    NULL    Impossible WHERE

Similarly `NOT (a!=a)` is always true.

EXPLAIN SELECT COUNT(*) FROM t1 WHERE not (a!=a);
id     select_type     table   type    possible_keys   key     key_len ref     rows    Extra
1      SIMPLE  NULL    NULL    NULL    NULL    NULL    NULL    NULL    Select tables optimized away