Make the range optimizer not call records_in_range() when it would
not give any benefit.

Part #2: make tree_or(tree1, tree2) to reuse tree1 for the result object
for simple cases. These include key IN (c1, ... cN).

The reuse was happening in old MySQL versions, but we stopped doing it
in the "fair choice between range and index_merge" patch.

MDEV-10154 - Remove some unnecessary parentheses

Post-fix #2:
- Update test results
- Make the optimization conditional under @@optimizer_switch flag.
- The optimization is now disabled by default, so .result files
  are changed back to be what they were before the MDEV-8989 patch.

Add big_test and not_debug requirements to avoid timeouts.

Fix spelling: shhould -> should

A partial backport of 67f21fb3a077dedfd14b9ca720e926c55e682f93,
Bug#22283790: RANGE OPTIMIZER UTILIZES TOO MUCH MEMORY WITH MANY OR CONDITIONS

The backported part changes SEL_TREE::keys from being an array of
MAX_KEY elements (64*8=512 bytes) to a Mem_root_array<SEL_ARG*> (32 bytes +
alloc'ed array of as many elements as we need).

The patch doesn't fix the "not limiting memory" part, but the memory usage
is much lower with it.

utf8mb4_thai_520_w2, ucs2_thai_520_w2, utf16_thai_520_w2, utf32_thai_520_w2

  from ctype_uca.test. This is to reuse ctype_thai.inc for other Unicode
  character sets later
- Removing separate ctype_uca.result

  and including it from t/ctype_uca.test
- Deleting r/ctype_uca_th.result

They have bytes 0x25 and 0x5F. Testing that these bytes are treated as parts
of multi-byte characters rather than underscore and percent sign.

Mark gssapi plugin as stable. No open bug reports, and no further work planned, thus stable is accurate

Post-fix: add comments, remove dead-code.

- Changing strnxfrm_multiply from 8 to 4, as agreed with Pruet Boonma
- Adjusting tests

Variant #4 of the fix.

Make ORDER BY optimization functions take into account multiple
equalities. This is done in several places:
- remove_const() checks whether we can sort the first table in the
  join, or we need to put rows into temp.table and then sort.
- test_if_order_by_key() checks whether there are indexes that
  can be used to produce the required ordering
- make_unireg_sortorder() constructs sort criteria for filesort.

When simplify_joins() converts an outer join to an inner, it should
reset the value of TABLE::dep_tables.  This is needed, because the
function may have already set TABLE::dep_tables according to the outer
join dependency.

don't use MY_THREAD_SPECIFIC on the client side
in embedded:
1. server memory accounting does not track client
   side memory
2. in not embedded builds, this still *might* be
   useful for plugins (handlersocket, connect, etc)

including the test case:

https://github.com/mysql/mysql-server/commit/520aedfe
INNODB: "DATA DIRECTORY" OPTION OF CREATE TABLE FAILS WITH PWRITE() OS
ERROR 22
Fix for version mysql-5.6
PROBLEM
========
For version mysql-5.6.27 onwards InnoDB fails to create a table
with explicit 'data directory' option when Innodb_flush_method
is set to O_DIRECT.While creating link file we get a  a pwrite
error 22 due to the alignment restrictions imposed by O_DIRECT
flag  which is being set for the link file created.

FIX
===
Fixed the above issue by making use of file IO functions while
creating the link file that wouldn't let the O_DIRECT flag
restrictions arise.
Reviewed-by: Kevin Lewis <kevin.lewis@oracle.com>
Reviewed-by: Shaohua Wang <shaohua.wang@oracle.com>
RB: 11387

Do not allow NULL password to pass directly to password
validation plugin.

An additional warning saying "tc-log cannot be enabled"
is emitted when InnoDB is installed at runtime on mysqld
built with wsrep-patch (-DWITH_WSREP=ON).

This happens because, installing InnoDB increments the
total number of 2pc-capable engines and with wsrep-patch
already enabled - the total count goes >1. Even though,
this condition is sufficient to enable tc-logging, it is
not permitted at runtime, and thus the warning.

Updated the testcase to avoid the warning.

Ha_trx_info should not be reset in ha_fake_trx_id() as it is
later used during commit.

This is to ensure that the list of valid values for
METADATA_LOCK_INFO fields is always kept in sync with
the parent MDL types.

Xtrabackup-based SST method uses socat. Move it from
Suggests to Depends list.

10.1 introduced a problem:
Execution time for various recursive stages
(walk, update_used_table, and propagate_equal_fields)
in NULLIF is O(recursion_level^2), because complexity is
doubled on every recursion level when we copy args[0] to args[2].

This change fixes to avoid unnecessary recursion in:
- Item_func_nullif::walk
- Item_func_nullif::update_used_tables
- Item_func_nullif::propagate_equal_fields
when possible.