- if test_if_skip_sort_order() decides to switch to using an index, or
  switch from using ref to using quick select, it should set all
  members accordingly.

Re-work test_if_order_by_key() to work correctly for extended indexes.

Fix test_if_skip_sort_order() logic:
WHEN
we use index X, which doesn't produce needed ordering, but there is
an index Y which does and has the same prefix as used prefix of X
THEN
don't just switch to using ref access on Y. If range(Y) would use more
key parts, use range(Y).

on binlog_innodb_row test.

result of innodb_sys_index test.

Fixed test failures seen on defragment tests, innodb.innodb-wl5522-debug-zip
and innodb.innodb_bug12902967.

SHOW COLUMNS and SHOW KEYS commands fill IS_table_read_plan
in a special way - they don't set or use lookup_field_vals
member.

Added a "trivial_show_command" flag that signals that
lookup_field_vals has no valid data, made EXPLAIN code honor it.

The problem was caused by the following scenario:
- range optimizer picks an index IDX1 which doesn't match the ORDER BY ...
  LIMIT clause.
- test_if_skip_sort_order() decides to switch to index IDX2 which matches
  the ORDER BY ... LIMIT.
- it runs SQL_SELECT::test_quick_select() for the second time to produce
  an quick select for IDX2.
- However, test_quick_select() would figure that full index scan on IDX1
  is still cheaper (its calculations ignore the LIMIT n).

Fixed this by
- passing force_quick_range=true to test_quick_select()
- in test_quick_select, don't consider full index scans if the mentioned
  parameter is true.

Numerous changes in .result files are caused by test_quick_select() being
run after "early/late NULLs filtering" feature has injected NOT NULL
condition.

  MDEV-6656: Test wsrep.variables hangs

  Analysis: wsrep_applier_thread shutdown signaling does not always work
  correctly causing a timing problem where main thread is waiting in a
  condition variable a signal that all worker threads to end.

option.

When ORDER BY ... LIMIT check whether it should switch from index IDX1
to index IDX2, it should not ignore the fact that IDX2 may have a
potential range or ref(const) access.
Istead, it should calculate their costs: there is now a saved range
optimizer cost and code to re-calculate what best_access_path()
calculated for ref(const).

/* in current cost model these two can be very different
numbers unfortunately */

Let range optimizer remove parts of OR-clauses for which range analysis
produced SEL_TREE(IMPOSSIBLE).
There is no need to remove parts of AND-clauses: either they are inside
of OR (and the whole AND-clause will be removed), or the AND-clause is
at the top level, in which case the whole WHERE (or ON) is always FALSE
and this is a degenerate case which receives special treatment.

The removal process takes care not to produce 1-way ORs (in that case
we substitute the OR for its remaining member).

    Merged lp:maria/maria-10.0-galera up to revision 3880.

    Added a new functions to handler API to forcefully abort_transaction,
    producing fake_trx_id, get_checkpoint and set_checkpoint for XA. These
    were added for future possiblity to add more storage engines that
    could use galera replication.

Merged lp:maria/maria-10.0-galera up to revision 3879.

Added a new functions to handler API to forcefully abort_transaction,
producing fake_trx_id, get_checkpoint and set_checkpoint for XA. These
were added for future possiblity to add more storage engines that
could use galera replication.

Added a new functions to handler API to forcefully abort_transaction,
producing fake_trx_id, get_checkpoint and set_checkpoint for XA. These
were added for future possiblity to add more storage engines that
could use galera replication.

Reverted workaround for gcc bug, which was fixed 3 years ago:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=34772

3871..3879.

IS [NOT] NULL predicate is sargable within an outer join. Range
analysis only uses predicates from ON expressions, which have
regular semantics (without null-complemented rows, etc).
There is no reason not use IS [NOT] NULL predicates.