trx_undo_page_get_prev_rec(), trx_undo_page_get_last_rec(),
trx_undo_page_get_first_rec(), trx_undo_page_get_start():
Move to the only caller, trx0undo.cc.

Add some const qualifiers.

trx_rseg_get_nth_undo(), trx_rsegf_undo_find_free():
Add a const qualifier, and remove the unused parameter mtr_t*.

trx_sysf_t: Remove.

trx_sysf_get(): Return the TRX_SYS page, not a pointer within it.

trx_sysf_rseg_get_space(), trx_sysf_rseg_get_page_no():
Remove a parameter, and merge the declaration and definition.
Take the TRX_SYS page as a parameter.

TRX_SYS_N_RSEGS: Correct the comment.

trx_sysf_rseg_find_free(), trx_sys_update_mysql_binlog_offset(),
trx_sys_update_wsrep_checkpoint(): Take the TRX_SYS page as a parameter.

trx_rseg_header_create(): Add a parameter for the TRX_SYS page.

trx_sysf_rseg_set_space(), trx_sysf_rseg_set_page_no(): Remove;
merge to the only caller, trx_rseg_header_create().

srv_init_abort_low(): Call srv_shutdown_bg_undo_sources() so that if
startup aborts while creating InnoDB system tables, the shutdown will
proceed correctly.

server crash in JOIN::fix_all_splittings_in_plan

Cost formulas must take into account the case when a splittable table
has now rows.

Only give warning if warnings > 2, as there is no plan to change
the current behavior.

- When adding LEX_CSTRING to String, we are now checking that
  string is \0 terminated (as normally LEX_CSTRING should be
  usable for printf(). In the cases when one wants to avoid the
  checking one can use String->append(ptr, length) instead of just
  String->append(LEX_CSTRING*)

This preserves const str for constant strings

Other things
- A few variables where changed from LEX_STRING to LEX_CSTRING
- Incident_log_event::Incident_log_event and record_incident where
  changed to take LEX_CSTRING* as an argument instead of LEX_STRING

This is to make it easier to use the
create_mysqld_error_find_printf_error tool to find wrong print

Rename was done as the old 'name' hide the original item name.

This was done in, among other things:
- thd->db and thd->db_length
- TABLE_LIST tablename, db, alias and schema_name
- Audit plugin database name
- lex->db
- All db and table names in Alter_table_ctx
- st_select_lex db

Other things:
- Changed a lot of functions to take const LEX_CSTRING* as argument
  for db, table_name and alias. See init_one_table() as an example.
- Changed some function arguments from LEX_CSTRING to const LEX_CSTRING
- Changed some lists from LEX_STRING to LEX_CSTRING
- threads_mysql.result changed because process list_db wasn't always
  correctly updated
- New append_identifier() function that takes LEX_CSTRING* as arguments
- Added new element tmp_buff to Alter_table_ctx to separate temp name
  handling from temporary space
- Ensure we store the length after my_casedn_str() of table/db names
- Removed not used version of rename_table_in_stat_tables()
- Changed Natural_join_column::table_name and db_name() to never return
  NULL (used for print)
- thd->get_db() now returns db as a printable string (thd->db.str or "")

MDEV-11415 Remove excessive undo logging during ALTER TABLE…ALGORITHM=COPY

Move a test from innodb.rename_table_debug to innodb.alter_copy.

ha_innobase::extra(HA_EXTRA_BEGIN_ALTER_COPY): Register id-versioned
tables so that mysql.transaction_registry will be updated, even for
empty tables that are subjected to ALTER TABLE…ALGORITHM=COPY.

If a crash occurs during ALTER TABLE…ALGORITHM=COPY, InnoDB would spend
a lot of time rolling back writes to the intermediate copy of the table.
To reduce the amount of busy work done, a work-around was introduced in
commit fd069e2b in MySQL 4.1.8 and 5.0.2,
to commit the transaction after every 10,000 inserted rows.

A proper fix would have been to disable the undo logging altogether and
to simply drop the intermediate copy of the table on subsequent server
startup. This is what happens in MariaDB 10.3 with MDEV-14717,MDEV-14585.
In MariaDB 10.2, the intermediate copy of the table would be left behind
with a name starting with the string #sql.

This is a backport of a bug fix from MySQL 8.0.0 to MariaDB,
contributed by jixianliang <271365745@qq.com>.

Unlike recent MySQL, MariaDB supports ALTER IGNORE. For that operation
InnoDB must for now keep the undo logging enabled, so that the latest
row can be rolled back in case of an error.

In Galera cluster, the LOAD DATA statement will retain the existing
behaviour and commit the transaction after every 10,000 rows if
the parameter wsrep_load_data_splitting=ON is set. The logic to do
so (the wsrep_load_data_split() function and the call
handler::extra(HA_EXTRA_FAKE_START_STMT)) are joint work
by Ji Xianliang and Marko Mäkelä.

The original fix:

Author: Thirunarayanan Balathandayuthapani <thirunarayanan.balathandayuth@oracle.com>
Date:   Wed Dec 2 16:09:15 2015 +0530

Bug#17479594 AVOID INTERMEDIATE COMMIT WHILE DOING ALTER TABLE ALGORITHM=COPY

Problem:

During ALTER TABLE, we commit and restart the transaction for every
10,000 rows, so that the rollback after recovery would not take so long.

Fix:

Suppress the undo logging during copy alter operation. If fts_index is
present then insert directly into fts auxiliary table rather
than doing at commit time.

ha_innobase::num_write_row: Remove the variable.

ha_innobase::write_row(): Remove the hack for committing every 10000 rows.

row_lock_table_for_mysql(): Remove the extra 2 parameters.

lock_get_src_table(), lock_is_table_exclusive(): Remove.
Reviewed-by: Marko Mäkelä <marko.makela@oracle.com>
Reviewed-by: Shaohua Wang <shaohua.wang@oracle.com>
Reviewed-by: Jon Olav Hauglid <jon.hauglid@oracle.com>

Fortify wsrep_hton so that wsrep calls are not done to NULL-pointers.

        Implementing the 'IF EXISTS' option for statements
        ALTER TABLE ALTER COLUMN SET/DROP DEFAULT.

- Galera tests that was not updated with connection change
  messages
- Test where out of memory error was changed (We are now using the
  standard out of memory error in most places)
- Removed tokudb tests that uses include files that doesn't exist
  in MariaDB
- Removed not supported mariadb startup option from option file

- Galera tests that was not updated with connection change
  messages
- Disabled some TokuDB tests that always timed out.
  These should be enabled again when we have an option to
  specicy timeouts per tests.

Do not apply splitting for constant tables.

Do not SET DEBUG_DBUG=-d,... in tests. To disable debug instrumentation,
save and restore the original value of the variable DEBUG_DBUG.
Assigning -d,... will enable the output of a lot of unrelated DBUG
messages to the server error log.

rx_i_s_cache_t is now bool, not ibool.

The patch for MDEV-15107 fixed this problem. Adding tests only.

Tests started to fail after a merge of MDEV-15107 (from bb-10.2-ext to 10.3),
because MDEV-15107 additionally fixed this problem:
  MDEV-15112 Inconsistent evaluation of spvariable=0 in strict mode

Modifying tests not to reply on the pre-MDEV-15112 behavior.

This reverts commit 3486135b.

The commit comment ended in the words: "This is needed later."
Apparently the "later" never arrived.

Remove unnecessary repeated lookups for undo pages.

trx_undo_assign(), trx_undo_assign_low(), trx_undo_seg_create(),
trx_undo_create(): Return the undo log block to the caller.

Inside InnoDB, each mini-transaction that generates any redo log records
will acquire log_sys->mutex during mtr_t::commit() in order to copy the
records into the global log_sys->buf for writing into the redo log file.

For single-row transactions, this incurs quite a bit of overhead.
We would use two mini-transactions for writing a record into a
freshly updated undo log page. (Only if the undo record will
not fit in that page, then we will have to commit and restart
the mini-transaction.)

trx_undo_assign(): Assign undo log for a persistent transaction,
or return the already assigned one.

trx_undo_assign_low(): Assign undo log for an operation on a
persistent or temporary table.

trx_undo_create(), trx_undo_reuse_cached(): Remove redundant parameters.
Merge the logic from trx_undo_mark_as_dict_operation().