row_merge_read_clustered_index(): The row->fields[] could point
to a record in the clustered index page of the source table, or
to an old version of the record that was constructed in row_heap.

If the row->fields[] points to the clustered index page, then
we were modifying buffer pool data without holding appropriate
block->lock and without appropriate redo logging. The intention
was to modify a copy of the data, not the source file page,
because concurrent readers would still very much need the original
values of the DB_TRX_ID,DB_ROLL_PTR for their multi-versioning.

Either way, it is simplest to not write anything at all, and to
make row->fields[] point to the constant reset_trx_id.

so that even the ancient patch 2.5.4 could apply it correctly.

fixes centos5-x86

Follow-up to MDEV-13570 Assertion failure !srv_read_only_mode in --innodb-read-only shutdown when buf_resize_thread is active

logs_empty_and_mark_files_at_shutdown(): Actually skip the debug assertion
when the buf_resize_thread is active. The previous fix skipped the
debug assertion failure when buf_dump_thread is active. Both these
threads are created also in innodb_read_only mode. Depending on how
fast these threads react to the shutdown signal, the debug assertion
could be triggered.

There is no impact on non-debug servers, and very little impact on
debug servers either, because in innodb_read_only shutdown, no InnoDB
files will need to be written.

followup for 62139dc2

MDEV-13690: Remove unnecessary innodb_use_mtflush, innodb_mtflush_threads parameters and related code

Users can use innodb-page-cleaners instead.

innobase_rec_reset(): Remove. This function was introduced in the
InnoDB Plugin for MySQL 5.1, which later evolved into MySQL 5.5.
There used to be a bug that ADD UNIQUE INDEX would not always correctly
report the duplicate key value of the secondary index. This function
ensured that instead of reporting total garbage values, InnoDB
would report NULL.

It looks like the function was made unnecessary in MySQL 5.6.6 by
https://github.com/mysql/mysql-server/commit/d143097eb1e02904baed34990db637ff68fe3113

The corresponding test was subsequently adjusted in
https://github.com/mysql/mysql-server/commit/fde80cf49d4b7635d2aef47d8a77681f2df62105

The ALTER TABLE tests were imported to MariaDB as part of MDEV-13625,
and these tests do pass with this change.

The unnecessary function did not do any harm before MDEV-11371 introduced
compressed columns.

One question remains: What if we needed to report a duplicate key value
for a compressed column? The simple answer is that the test
main.column_compression demonstrates that no indexes can be defined
on compressed columns.

pretty_print_engine_list(): When the plugin list is empty, return
an empty string instead of allocating a buffer of 0 bytes and then
trying to write a NUL byte into it.

After MDEV-12288 and MDEV-13536, the DB_TRX_ID of old clustered index
records for which no history is available should be reset to 0.

This caused crashes in online table-rebuilding ALTER, because the
row_log_table_apply() is built on the assumption that the PRIMARY KEY
together with DB_TRX_ID,DB_ROLL_PTR identifies the record.

Both when copying the old table and when writing log about changes to
the old table, we must map "old" DB_TRX_ID to 0. "old" here is simply
"older than the trx_id of the ALTER TABLE transaction", because
the MDL_EXCLUSIVE (and exclusive InnoDB table lock) in
ha_innobase::prepare_inplace_alter_table() forces any transactions
accessing the table to commit or rollback. So, we know that we can
safely reset any DB_TRX_ID in the table that is older than the
transaction ID of the ALTER TABLE, because the undo log history would be
lost in a table-rebuilding ALTER.

Note: After a table-rebuilding online ALTER TABLE, the rebuilt table
may end up containing some nonzero DB_TRX_ID columns. The apply logic
identifies the rows by the combination of PRIMARY KEY and DB_TRX_ID.
These nonzero DB_TRX_ID would necessarily refer to concurrent DML
operations that were started during ha_innobase::inplace_alter_table().

row_log_allocate(): Add a parameter for the ALTER TABLE transaction.

row_log_t::min_trx: The ALTER TABLE transaction ID.

trx_id_check(): A debug function to check that DB_TRX_ID makes sense
(is either 0 or bigger than the ALTER TABLE transaction ID).

reset_trx_id[]: The reset DB_TRX_ID,DB_ROLL_PTR columns.

row_log_table_delete(), row_log_table_get_pk(): Reset the
DB_TRX_ID,DB_ROLL_PTR when they precede the ALTER TABLE transaction.

row_log_table_apply_delete(), row_log_table_apply_update():
Assert trx_id_check().

row_merge_insert_index_tuples(): Remove the unused parameter trx_id.

row_merge_read_clustered_index(): In a table-rebuilding ALTER,
reset the DB_TRX_ID,DB_ROLL_PTR when they precede the ALTER TABLE
transaction. Assert trx_id_check() on clustered index records that
are being buffered.

char* parameter is expected by the message ER_KEY_COLUMN_DOES_NOT_EXITS,
thus pass char*, rather than LEX_STRING.

ERROR_FILE_SYSTEM_LIMITATION was seen by support when backing up large
file. However mariabackup error message was not very helpful,
since it mapped the error to generic catch-all EINVAL.

With the patch, ERROR_FILE_SYSTEM_LIMITATION will be mapped to more
appropriate EFBIG. Also add mapping from ERROR_NO_SYSTEM_RESOURCES
to ENOMEM.

Storage engine independent support for column compression.

TINYBLOB, BLOB, MEDIUMBLOB, LONGBLOB, TINYTEXT, TEXT, MEDIUMTEXT, LONGTEXT,
VARCHAR and VARBINARY columns can be compressed.

New COMPRESSED column attribute added:
COMPRESSED[=<compression_method>]

System variables added:
column_compression_threshold
column_compression_zlib_level
column_compression_zlib_strategy
column_compression_zlib_wrap

Status variables added:
Column_compressions
Column_decompressions

Limitations:
- the only supported method currently is zlib
- CSV storage engine stores data uncompressed on-disk even if COMPRESSED
  attribute is present
- it is not possible to create indexes over compressed columns.

CURRENT_TEST: galera.galera_kill_applier
mysqltest: At line 14: query 'KILL $applier_thread' failed with wrong
errno 1064: 'You have an error in your SQL syntax; check the manual
that corresponds to your MariaDB server version for the right syntax
to use near '' at line 1', instead of 1095...

It doesn't serve any purpose, but generates extra virtual function call.

These parameters and associated code is to be removed in 10.3.
Users can use innodb-page-cleaners > 1 instead.

Updated qc_info tests, added new test that checks HITS is incremented.

Added hit_count field to Query_cache_query and methods to get and increment it.
The counter is incremented when query results are read from query cache.

READ_RECORD read_record;
...
// this
// read_record.read_record(&read_record);
// becomes just
read_record.read_record();

MDEV-12741: innodb.ibuf_not_empty failed in buildbot with "InnoDB: Trying to do I/O to a tablespace which does not exist"

Background thread is doing ibuf merge, in buf0rea.cc buf_read_ibuf_merge_pages().
It first tries to get page_size and if space is not found it deletes them, but
as we do not hold any mutexes, space can be marked as stopped between that
and buf_read_page_low() for same space. This naturally leads seen error
message on log.

buf_read_page_low(): Add parameter ignore_missing_space = false that
is passed to fil_io()

buf_read_ibuf_merge_pages(): call buf_read_page_low with
ignore_missing_space = true, this function will handle missing
space error code after buf_read_page_low returns.

fil_io(): if ignore_missing_space = true do not print error
message about trying to do I/0 for missing space, just return
correct error code that is handled later.

Make rocksdb.bloomfilter* tests 1.8x faster by doing loading in bulk

There is a race condition in InnoDB startup. A number of
fil_crypt_thread are created by fil_crypt_threads_init(). These threads
may call btr_scrub_complete_space() before btr_scrub_init() was called.
Those too early calls would be accessing an uninitialized scrub_stat_mutex.

innobase_start_or_create_for_mysql(): Invoke btr_scrub_init() before
fil_crypt_threads_init().

fil_crypt_complete_rotate_space(): Only invoke btr_scrub_complete_space()
if scrubbing is enabled. There is no need to update the statistics if
it is not enabled.

ATTRIBUTE_NORETURN is supported on all platforms (MSVS and GCC-like).
It declares that a function will not return; instead, the thread or
the whole process will terminate.

ATTRIBUTE_COLD is supported starting with GCC 4.3. It declares that
a function is supposed to be executed rarely. Rarely used error-handling
functions and functions that emit messages to the error log should be
tagged such.

galera.galera_kill_applier: Make the test less likely to fail
by adding sleep time.

galera.query_cache: Remove data truncation.

Part of the test file looks like it has been misinterpreted as latin1
and wrongly converted to UTF-8 encoding. In MariaDB 10.1, the server would
only warn about data truncation and not issue an error. 10.2 is stricter.
(The test should be carefully reviewed if it really makes sense.)

For running the Galera tests, the variable my_disable_leak_check
was set to true in order to avoid assertions due to memory leaks
at shutdown.

Some adjustments due to MDEV-13625 (merge InnoDB tests from MySQL 5.6)
were performed. The most notable behaviour changes from 10.0 and 10.1
are the following:

* innodb.innodb-table-online: adjustments for the DROP COLUMN
behaviour change (MDEV-11114, MDEV-13613)

* innodb.innodb-index-online-fk: the removal of a (1,NULL) record
from the result; originally removed in MySQL 5.7 in the
Oracle Bug #16244691 fix
https://github.com/mysql/mysql-server/commit/377774689bf6a16af74182753fe950d514c2c6dd

* innodb.create-index-debug: disabled due to MDEV-13680
(the MySQL Bug #77497 fix was not merged from 5.6 to 5.7.10)

* innodb.innodb-alter-autoinc: MariaDB 10.2 behaves like MySQL 5.6/5.7,
while MariaDB 10.0 and 10.1 assign different values when
auto_increment_increment or auto_increment_offset are used.
Also MySQL 5.6/5.7 exhibit different behaviour between
LGORITHM=INPLACE and ALGORITHM=COPY, so something needs to be tested
and fixed in both MariaDB 10.0 and 10.2.

* innodb.innodb-wl5980-alter: disabled because it would trigger an
InnoDB assertion failure (MDEV-13668 may need additional effort in 10.2)

After MDEV-13583: Improvements for MTR rebootstrap introduced in
MDEV-12042 bootsrap correctly creates mysql/innodb_table_stats
and mysql/innodb_index_stats InnoDB tables before innodb_encryption
test starts. These tables are also encrypted or decrypted, thus
we need to wait also these tables (if not we could randomly
get different results as system tablespace and these tables
are encrypted or decrypted in parallel).

Problem was incorrect definition of wsrep_recovery,
trx_sys_update_wsrep_checkpoint and
trx_sys_read_wsrep_checkpoint functions causing
innodb_plugin not to load as there was undefined symbols.