In this case we are setting the field Item_func_eq::in_eqaulity_no for the semi-join equalities.
This helps us to remove these equalites as the inner tables are not available during parent select execution
while the outer tables are not available during materialization phase.
We only have it set for the equalites for the fields involved with the IN subquery
and reset it for the equalities which do not belong to the IN subquery.

For example in case of nested IN subqueries:

    SELECT t1.a FROM t1 WHERE t1.a IN
      (SELECT t2.a FROM t2 where t2.b IN
          (select t3.b from t3 where t3.c=27 ))

there are two equalites involving the fields of the IN subquery

1) t2.b = t3.b :  the field Item_func_eq::in_eqaulity_no is set when we merge the grandchild select into the child select
2) t1.a = t2.a :  the field Item_func_eq::in_eqaulity_no is set when we merge the child select into the parent select

But when we perform case 2) we should ensure that we reset the equalities in the child's WHERE clause.

MDEV-16751: Server crashes in st_join_table::cleanup or TABLE_LIST::is_with_table_recursive_reference
            with join_cache_level>2

During muliple equality propagation for a query in which we have an IN subquery, the items in the select list of the
subquery may not be part of the multiple equality because there might be another occurence of the same field in the
where clause of the subquery.
So we keyuse_is_valid_for_access_in_chosen_plan function which expects the items in the select list of the subquery to
be same to the ones in the multiple equality (through these multiple equalities we create keyuse array).
The solution would be that we expect the same field not the same Item because when we have SEMI JOIN MATERIALIZATION SCAN,
we use copy back technique to copies back the materialised table fields to the original fields of the base tables.

This patch fixes another problem introduced by the patch for mdev-4817.
The latter changed Item_cond::fix_fields() in such a way that it could
call the virtual method is_expensive(). With the first its call
the method saves the result in Item::is_expensive_cache. For all next
calls the method returns the result from this cache. So if the item
once was determined as expensive the method always returns true.
For subqueries it's not good, because non-optimized subqueries always
is considered as expensive.
It means that the cache should be invalidated after the call of
optimize_constant_subqueries().

Due to a legacy bug in the code of make_join_statistics() detecting
so-called constant tables could miss some of them in rare queries
that used RIGHT JOIN. As a result these queries had execution plans
different from the execution plans of the equivalent queries with
LEFT JOIN.
Besides starting from 10.2 this could trigger an assertion failure.

Closes #551

fix_semijoin_strategies_for_picked_join_order() should set
join->sjm_lookup_tables to be a bitmap of tables inside
SJ-Materialization-Lookup nests.

In this issue we are using derived_with_keys optimization and we are using these keys to do a hash join which is incorrect.
We cannot create keys for dervied tables whose keyparts have types are of BLOB or TEXT type. TEXT or BLOB  columns can only be
indexed over a specified length.

When the definition of the index used for hash join was created
in create_hj_key_for_table() it could cause memory overwrite
due to a bug that led to an underestimation of the number of
the index component.

For the purpose of reporting an error to error log, shutdown thread was
attempting to access current_thd->variables.lc_messages->errmsgs->errmsgs.
Whereas current_thd was NULL.

We should log errors according to global lc_messages setting instead of
session setting.

MDEV-16512 Server crashes in find_field_in_table_ref on 2nd
execution of SP referring to non-existing field

Problem was in the natural join code that it changed TABLE_LIST and
Item_fields but didn't restore changed things if things goes wrong
and was not able to re-execute after failure.
Some of the problems could have been avoided if we would have run
fix_fields before doing natural join transformations.

Fixed by marking functions complete AFTER they had executed, instead at
start.
I had also to change some tests that checked if Item_fields are usable.

This doesn't fix all known problems, but at least avoids some crashes.
What should be done in the near future is to mark the statement in the SP
as 'not re-executable' and force a reparse of it on next execution.

Reviewer: Sergei Petrunia <psergey@askmonty.org>

This reverts commit d39629f0.

Because running mtr for many hours with no output whatsoever
is not really what we should do.

And in 5.5 `make test` just works anyway, nothing to fix here.

MDEV-16534 PPC64: Unexpected error with a negative value into auto-increment columns in HEAP, MyISAM, ARIA

Added unregistering writers in case of log error.
Added more debugging control about adding/removing writers to the buffers.

           SELECT .. LIMIT 0 (new variant)

This is another attempt to fix the problem of mdev-14515.

update table->pos_in_table_list during prepare,
just like it's done in normal execution.

otherwise it'll be a dangling pointer

adjust tests

rewrite tautological engine descriptions

The order of outputting stored procedures is important. Stored
procedures must be available on view creation, for views which make use
of them. Make sure to print them before outputting tables.

Undo the revert that happened by mystake in commit 7fca4b50.

GCC-8 introduced multiple warnings and increased the level of
strictness.

* -Wshadow will warn if a local variable shadows a typedef.
* GCC will also warn when memsetting a non-trivial type.
  In this case a non-trivial type can not have a custom constructor.
  For all intents and purposes, the class is trivially-copyable.
* GCC will also warn if you use too many paranthesses which are not
necessary

This reverts commit 1735fa34.

Assign all tests added via MY_ADD_TEST to a bogus default_ignore target,
so that they are not ran by default when doing bare make test. Add default
test named MTR that calls mysql-test-run suite, which is now the single
test run by make test.

In consequence, modified unit/suite.pm to exclude the MTR test and run the
real ctests flagged for default_ignore target, thus no circular
loop.

This is happening because they are declared as packed
and clang has -Waddress-of-packed-member when passing the
address of a packed member, a legit concern on different
architectures. The easiest way to get rid of the errors is to
remove the packed attribute from said structs.

Fix build on macOS 10.13:

39dceaae MDEV-10983: TokuDB does not compile on OS X 10.12
Make use of a different function to get the current tid.
Additionally, librt doesn't exist on OS X. Use System library instead.

 storage/tokudb/PerconaFT/cmake_modules/TokuFeatureDetection.cmake | 4 +++-
 storage/tokudb/PerconaFT/portability/portability.cc               | 9 ++++++++-
 storage/tokudb/PerconaFT/portability/tests/test-xid.cc            | 9 ++++++++-
 storage/tokudb/PerconaFT/portability/toku_config.h.in             | 1 +
 4 files changed, 20 insertions(+), 3 deletions(-)

The bug arises when one uses --auto-generate-sql-guid-primary (and
--auto-generate-sql-secondary-indexes) with mysqlslap and also have
sql_mode=STRICT_TRANS_TABLE.

When using this option, mysqlslap should create a column with varchar(36),
but it appears to create it as a varchar(32) only. Then if one has
sql_mode=STRICT_TRANS_TABLES, it throws an error, like:

  mysqlslap: Cannot run query INSERT INTO t1 VALUES (...)
  ERROR : Data too long for column 'id' at row 1

Upstream bug report: BUG#80329.

Partially revert 4ef74979
that caused regression.

Any ssl- option must imply use_ssl=1, even if mysql_set_ssl() was not
used.

For non-semi-join subquery optimization we do a cost based decision between
Materialisation and IN -> EXIST transformation. The issue in this case is that for IN->EXIST transformation
we run JOIN::reoptimize with the IN->EXISt conditions and we come up with a new query plan. But when we compare
the cost with Materialization, we make the decision to chose Materialization so we need to restore the query plan
for Materilization.
The saving and restoring for keyuse array and join_tab keyuse is only done when we have atleast
one element in the keyuse_array , we are now changing to do it even for 0 elements to main the generality.

gdb's "set args" equivalent for lldb would be "settings set target.run-args",
however it doesn't play well with double dashed args (--).

           upon SELECT .. LIMIT 0

The code must differentiate between a SELECT with contradictory
WHERE/HAVING and one with LIMIT 0.
Also for the latter printed 'Zero limit' instead of 'Impossible where'
in the EXPLAIN output.

It should work ok on all Unixes, but on Windows ,only worked by accident
in the past, with client not being Unicode safe.

It stopped working with Visual Studio 2017 15.7 update now.

When Item_insert_value needs a dummy field,
use zero-length Field_string, not Field_null.
The latter isn't compatible with CREATE ... SELECT.

Analyze core independently of max-save-datadir and max-save-core setting.

Increment $num_saved_cores only if core was actually saved.

"Move any core files from e.g. mysqltest" independently of
max-save-datadir setting. Note: it may overwrite core from mysqld, which
might not be desired (it did work this way even before).