InnoDB divides the allocation of undo logs into rollback segments.
The DB_ROLL_PTR system column of clustered indexes can address up to
128 rollback segments (TRX_SYS_N_RSEGS). Originally, InnoDB only
created one rollback segment. In MySQL 5.5 or in the InnoDB Plugin
for MySQL 5.1, all 128 rollback segments were created.

MySQL 5.7 hard-codes the rollback segment IDs 1..32 for temporary undo logs.
On upgrade, unless a slow shutdown (innodb_fast_shutdown=0)
was performed on the old server instance, these rollback segments
could be in use by transactions that are in XA PREPARE state or
transactions that were left behind by a server kill followed by a
normal shutdown immediately after restart.

Persistent tables cannot refer to temporary undo logs or vice versa.
Therefore, we should keep two distinct sets of rollback segments:
one for persistent tables and another for temporary tables. In this way,
all 128 rollback segments will be available for both types of tables,
which could improve performance. Also, MariaDB 10.2 will remain more
compatible than MySQL 5.7 with data files from earlier versions of
MySQL or MariaDB.

trx_sys_t::temp_rsegs[TRX_SYS_N_RSEGS]: A new array of temporary
rollback segments. The trx_sys_t::rseg_array[TRX_SYS_N_RSEGS] will
be solely for persistent undo logs.

srv_tmp_undo_logs. Remove. Use the constant TRX_SYS_N_RSEGS.

srv_available_undo_logs: Change the type to ulong.

trx_rseg_get_on_id(): Remove. Instead, let the callers refer to
trx_sys directly.

trx_rseg_create(), trx_sysf_rseg_find_free(): Remove unneeded parameters.
These functions only deal with persistent undo logs.

trx_temp_rseg_create(): New function, to create all temporary rollback
segments at server startup.

trx_rseg_t::is_persistent(): Determine if the rollback segment is for
persistent tables.

trx_sys_is_noredo_rseg_slot(): Remove. The callers must know based on
context (such as table handle) whether the DB_ROLL_PTR is referring to
a persistent undo log.

trx_sys_create_rsegs(): Remove all parameters, which were always passed
as global variables. Instead, modify the global variables directly.

enum trx_rseg_type_t: Remove.

trx_t::get_temp_rseg(): A method to ensure that a temporary
rollback segment has been assigned for the transaction.

trx_t::assign_temp_rseg(): Replaces trx_assign_rseg().

trx_purge_free_segment(), trx_purge_truncate_rseg_history():
Remove the redundant variable noredo=false.
Temporary undo logs are discarded immediately at transaction commit
or rollback, not lazily by purge.

trx_purge_mark_undo_for_truncate(): Remove references to the
temporary rollback segments.

trx_purge_mark_undo_for_truncate(): Remove a check for temporary
rollback segments. Only the dedicated persistent undo log tablespaces
can be truncated.

trx_undo_get_undo_rec_low(), trx_undo_get_undo_rec(): Add the
parameter is_temp.

trx_rseg_mem_restore(): Split from trx_rseg_mem_create().
Initialize the undo log and the rollback segment from the file
data structures.

trx_sysf_get_n_rseg_slots(): Renamed from
trx_sysf_used_slots_for_redo_rseg(). Count the persistent
rollback segment headers that have been initialized.

trx_sys_close(): Also free trx_sys->temp_rsegs[].

get_next_redo_rseg(): Merged to trx_assign_rseg_low().

trx_assign_rseg_low(): Remove the parameters and access the
global variables directly. Revert to simple round-robin, now that
the whole trx_sys->rseg_array[] is for persistent undo log again.

get_next_noredo_rseg(): Moved to trx_t::assign_temp_rseg().

srv_undo_tablespaces_init(): Remove some parameters and use the
global variables directly. Clarify some error messages.

Adjust the test innodb.log_file. Apparently, before these changes,
InnoDB somehow ignored missing dedicated undo tablespace files that
are pointed by the TRX_SYS header page, possibly losing part of
essential transaction system state.

this closes the memory leak, that started to appear after da5c3e03

trx::has_logged_persistent(): Renamed from trx_is_redo_rseg_updated().
Determines if a transaction has generated any persistent undo log.

trx::has_logged(): Renamed from trx_is_rseg_updated().
Determines if a transaction has generated any undo log.

Added CHECK constraints to I_S.TABLE_CONSTRAINTS.
Fixed a bug regarding virtual column definitions whose name is the field name.
Added test case: check_constraint_show

The function Item::split_sum_func2() incorrectly processed the function
items with window functions that were not window functions themselfes
and were used as arguments of other functions.

With the current design the function copy_funcs() should ignore
the items with window functions from the array **func_ptr.

followup for da5c3e03

moved to storage/innobase/

also removed duplicate checks from storage/innobase/CMakeLists.txt
(they're all in storage/innobase/innodb.cmake)

MDEV-11605 Assertion `(longlong) thd->status_var.local_memory_used >= 0 || !debug_assert_on_not_freed_memory' failed in my_malloc_size_cb_func

MyISAM in compute_vcols() - which is used only in mi_check code -
was computing indexed vcols into an internally allocated buffer
(not record[0]) and the buffer was calculated to be long enough to fit
every keyseg (a keyseg knows where its value in a record buffer is
and the length of the value).

This logic didn' work for prefix keys, because the keyseg length is the
length of a prefix, but the record buffer needs to fit the complete
value of a vcol. In this bug MyISAM was writing a 2K varchar
into a buffer too short.

Also it didn't work for repair-with-keycache, because that code
recalculats all vcols, not only indexed ones.

So, the buffer size (MYISAM_SHARE::vreclength) should include all
vcols' full lengths. But it was calculated in mi_open and low-level
MyISAM code has no knowledge of vcols.

As a fix we now recalculate MYISAM_SHARE::vreclength in
ha_myisam::setup_vcols_for_repair() which is always called
before compute_vcols().

MDEV-10354 Assertion `! is_set()' failed in Diagnostics_area::set_ok_status on CREATE TABLE with invalid default

test case

MDEV-11114 Cannot drop column referenced by CHECK constraint: Unknown column 'a' in 'virtual column function'

clarify the error message

add columns needed for CHECK constraints not only to read_set,
but also to vcol_set.

give threads more descriptive names

don't build the server with jemalloc.
only build tokudb with it.
move tokudb into a separate package, because it brings a new dependency

disable XtraDB in a way that makes it impossible to be built

* remove redundant casts
* fix fix_win_paths() not to pretend that it takes const char* string
  because it changes it. Fix its callers not to pass const strings
  into it.
* use _WIN32 not __WIN__

increase stack size for labrador

* add a clarifying comment
* apply /wd4244 /wd4146 to ref10 source files, not to the library

        Added IS_GENERATED and GENERATION_EXPRESSION columns required by
        the SQL standard

The function st_select_lex_unit::exec_recursive() incorrectly determined
that a CTE mutually recursive with some others was stabilized in the case
when the non-recursive part of the CTE returned an empty set. As a result
the server fell into an infinite loop when executing a query using
this CTE.

Do not truncate pointers returned by _findfirst to int.

Mutually recursive CTE could cause a crash of the server in the case
when they were not Standard compliant. The crash happened in
mysql_derived_prepare(), because the destructor the derived_result
object created for a CTE that was mutually recursive with some others
was called twice. Yet this destructor should not be called for resursive
references.

The method With_element::check_unrestricted_recursive() icorrectly performed
the check that no recursive reference is not encountered in inner parts of
outer joins. As a result the server reported errors for valid specifications
with outer joins.

This could fix a race condition between mysqld and perl on Windows.

The test was unnecessarily depending on InnoDB purge, which can
sometimes fail to proceed.

Let us rewrite the test to use BEGIN;INSERT;ROLLBACK to cause the
immediate removal of the desired records.