... using TO

Fixed the 'wsrep_replicate_myisam' check to allow only limited
set of commands. Added a debug assert to discover such cases.

... with wsrep_replicate_myisam enabled

Internal updates to system statistical tables could wrongly
trigger an additional total-order replication if wsrep_repli
-cate_myisam is enabled.
Fixed by adding a check to skip total-order replication for
stat tables.

Essentially revert MDEV-6759, which addressed a double free of memory
by removing the freeing altogether, introducing the memory leaks.
No double free was observed when running the test suite -DWITH_ASAN.

Replace some mem_heap_free(foreign->heap) with dict_foreign_free(foreign)
so that the calls can be located and instrumented more easily when needed.

MySQL 5.7 supports only one shared temporary tablespace.

MariaDB 10.2 does not support any other shared InnoDB tablespaces than
the two predefined tablespaces: the persistent InnoDB system tablespace
(default file name ibdata1) and the temporary tablespace
(default file name ibtmp1).

InnoDB is unnecessarily allocating a tablespace ID for the predefined
temporary tablespace on every startup, and it is in several places
testing whether a tablespace ID matches this dynamically generated ID.

We should use a compile-time constant to reduce code size and to avoid
unnecessary updates to the DICT_HDR page at every startup.

Using a hard-coded tablespace ID will should make it easier to remove the
TEMPORARY flag from FSP_SPACE_FLAGS in MDEV-11202.

        JSON depth calculation fixed.

        String insertion fixed.

        The Item_func_json_contains_path was mistakenly set with the
        no '*' paths limitation.

MDEV-11562 Assertion `js->state == JST_VALUE' failed in check_contains(json_engine_t*, json_engine_t*).

        check_contains() fixed. When an item of an array is a complex
        structure, it can be half-read after the end of the recursive
        check_contains() call. So we just manually get to it's ending.

in slow shutdown mode don't stop purge threads until they've
purged everything there is

in slow shutdown mode stop all bg threads that might generate
new undo records to purge before stopping purge threads.

in slow shutdown mode purge threads really must exit only when there is
nothing to purge. Restore the trx_commit_disallowed check and
don't stop purge threads until all connection thread transactions
are gone.

The patch for bug mdev-10882 tried to fix it by providing an
implementation of the virtual method build_clone for the class
Item_cache. It's turned out that it is not easy provide a valid
implementation for Item_cache::build_clone(). At the same time
if the condition that can be pushed into a materialized view
contains a cached item this item can be substituted for a basic
constant of the same value. In such a way we can avoid building
proper clones for Item_cache objects when constructing pushdown
conditions.

* rpm upgrade fix
* update test results
* valgrind warning

        Now JSON functions return warnings if arguments are invalid.

name innodb background threads as such

MDEV-11518 Assertion `!table || (!table->read_set || bitmap_is_set(table->read_set, field_index))' failed in Field_long::val_int()

QUICK_RANGE_SELECT::init_ror_merged_scan() should
also set and restore TABLE::vcol_set

Aria supports virtual columns, but does not support indexes
on virtual columns. Let's issue an appropriate error in this case.

strangely enough, ?: variant does not link in some older gcc versions:

sql/sql_table.cc:6409: undefined reference to `Alter_inplace_info::ALTER_STORED_GCOL_EXPR'
sql/sql_table.cc:6409: undefined reference to `Alter_inplace_info::ALTER_VIRTUAL_GCOL_EXPR'

by introducing new Item::precedence() method and using it
to decide whether parentheses are required

* do setup/cleanup for charset and arena only once per table
  not for every vcol
* don't copy every vcol expression into table's memroot for parsing,
  do it in a temporary String buffer that is freed at the end
* add asserts

now, when expr_str is gone, expr_item can be unambiguously
renamed to expr.