In 10.3, all records will be processed by purge due to MDEV-12288.
But, the insert undo records do not contain a transaction identifier.

row_purge_parse_undo_rec(): Use node->trx_id=TRX_ID_MAX for the
insert undo records. We cannot skip table lookups for these records
after DISCARD TABLESPACE other than by 'detaching' the table from
the undo logs by updating SYS_TABLES.ID on both DISCARD TABLESPACE
and IMPORT TABLESPACE.

Also, remove a redundant condition that was introduced
in the merge commit 814205f3.

recv_parse_log_recs(): Do not compare type if ptr==end_ptr
(we have reached the end of the redo log parsing buffer),
because it will not have been correctly initialized in that case.

GCC 6 and later can optimize away the memset() that is part of
mem_heap_zalloc() in a placement new call. So, instead of relying
on that kind of initialization, explicitly initialize the necessary
fields in the constructors.

que_common_t::que_common_t(): Initialize more fields in the
default constructor.

purge_vcol_info_t::purge_vcol_info_t(): Initialize all fields in
the default constructor.

purge_node_t::purge_node_t(): Initialize all necessary fields.

Reference:

    https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71388

    https://gcc.gnu.org/ml/gcc/2016-02/msg00207.html

row_merge_create_fts_sort_index(): Initialize dict_col_t in
an unambiguous way. GCC 6 and later appear to be able to optimize
away the memset() that is part of mem_heap_zalloc() in the
placement new call. Let us avoid using placement new in order
to ensure that the objects will actually be initialized.

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71388

https://gcc.gnu.org/ml/gcc/2016-02/msg00207.html

While the latter reference hints that the optimization is only
applicable to non-POD types (and dict_col_t does not define
any member functions before 10.2), it is most consistent to
use the same initialization across all versions.

MDEV-17070 Table corruption or Assertion `table->file->stats.records > 0 || error' or Assertion `!is_set() || (m_status == DA_OK_BULK && is_bulk_op())' failed upon actions on temporary table

This was caused by a combination of factors:
* MyISAM/Aria temporary tables historically never saved the state
  to disk (MYI/MAI), because the state never needed to persist
* certain ALTER TABLE operations modify the original TABLE structure
  and if they fail, the original table has to be reopened to
  revert all changes (m_needs_reopen=1)

as a result, when ALTER fails and MyISAM/Aria temp table gets reopened,
it reads the stale state from the disk.

As a fix, MyISAM/Aria tables now *always* write the state to disk
on close, *unless* HA_EXTRA_PREPARE_FOR_DROP was done first. And
the server now always does HA_EXTRA_PREPARE_FOR_DROP before dropping
a temporary table.

JSON_ARRAY and JSON_OBJECT functions with no arguments now get the
connection charset. Item_func_convert_charset returns the correct
is_json() flag.

ALTER TABLE ... ADD FOREIGN KEY may trigger assertion failure when
it has LOCK=EXCLUSIVE clause or concurrent FLUSH TABLES is being
executed.

In both cases being altered table is marked as flushed, which forces
subsequent attempt to open parent table to re-open. Which in turn is
not allowed while transaction is running.

Rather than opening parent table, just take appropriate MDL lock.

Also removed table_already_fk_prelocked() check: MDL itself has much
better methods to handle duplicate locks. E.g. the former won't acquire
MDL_SHARED_NO_WRITE if it already has MDL_SHARED_READ.

read_command_buf was not freed at exit, which could cause a warning from
valgrind

Recalculate distinct pointer if we cut chain of SELECTs

Initialize node->trx_id before checking if a table can be skipped.

wait_all_purged.inc: Wait for 60 seconds instead of 30 seconds.
Purge can be slow on buildbot, especially in ASAN-instrumented builds.

purge_node_t::in_progress: Replaces purge_node_t::done.
Only present in debug builds.

purge_node_t::start(): Moved from the start of row_purge_step().

purge_node_t::end(): Replaces row_purge_end().

trx_purge_attach_undo_recs(): Omit a check from non-debug builds.

If a table has been dropped, rebuilt, or its tablespace has been
discarded or the table is corrupted, it does not make sense to
look up that table again while purging old undo log records.

purge_node_t::purge_node_t(): Replaces row_purge_node_create().

que_common_t::que_common_t(): Constructor.

row_import_update_index_root(): Remove the constant parameter
dict_locked=true, and update the table->def_trx_id in the cache.

purge_node_t::unavailable_table_id: The latest unavailable table ID,
to avoid future lookups.

purge_node_t::def_trx_id: The latest modification of the table
identified by unavailable_table_id, or TRX_ID_MAX.

purge_node_t::is_skipped(): Determine if a table should be skipped.

purge_node_t::skip(): Note that a table should be skipped.

MTR tests for clearing orphaned SR transactions in Galera

Fixed sync points in MW-388 and fixed SP wsrep error handling to
avoid propagating wsrep errors via client-server protocol response.

This can be useful:
UBSAN_OPTIONS=log_path=/some/path

clang users may want to increase stack size in include/my_pthread.h or enable
some optimizations

Clean up after commit 0957d257
which introduced some disorder (unsorted or duplicated test names).

Removed redundant initialisation in unireg_init(): already done by
mysql_init_variables().

Slave threads already check THD::killed, which eliminates the need to
check abort_loop.

Removed unused wsrep_kill_mysql().

modified:   suite/galera/t/galera_autoinc_sst_mariabackup.test

remove WSREP_SST_OPT_SUFFIX_VALUE, checking [mysqld] is covered in the parse_cnf --mysqld case also in wsrep_sst_xtrabackup-v2

wsrep_sst: remove WSREP_SST_OPT_SUFFIX_VALUE, checking [mysqld] is covered in the parse_cnf --mysqld case

modified:   mysql-test/suite/galera/disabled.def
modified:   mysql-test/suite/galera/r/galera_many_rows.result
modified:   mysql-test/suite/galera/t/galera_kill_nochanges.test
new file:   mysql-test/suite/galera/t/galera_many_rows.cnf
modified:   mysql-test/suite/galera/t/galera_many_rows.test
modified:   mysql-test/suite/galera/t/galera_var_dirty_reads.test
modified:   scripts/wsrep_sst_mariabackup.sh

galera.partition and galera.galera_binlog_stmt_autoinc regularly display
mismatching values for AUTO_INCREMENT columns.

galera.MW-336 often times out while waiting for something in PROCESSLIST.

Also, sort the test names, remove the redundant "galera." prefix and
fix typos in 2 test names.

TVC uses derived as singlatable calls