PROBLEM
-------

1. We are inserting a base column entry which causes an invalid value
   by the function provided to generate virtual column,but we go ahead
   and insert this due to ignore keyword.
2. We then delete this record, making this record delete marked in innodb.
   If we try to insert another record with the same pk as the deleted
   record and if the rec is not purged ,then we try to undelete mark this
   record and try to build a update vector with previous and updated value
   and while calculating the value of virtual column we get error from
   server that we cannot calculate this from base column.
   Innodb assumes that innobase_get_computed_value() Should always return
   a valid value for the base column present in the row. The failure of
   this call was not handled ,so we were crashing.

FIX

Thanks to commit 2614a0ab
before MDEV-5800, no version of MariaDB is affected by this bug
that was fixed in MySQL 5.7.25.

Rename it because it caused parser warning whenever --backup was used.

dict_sys_get_size(): Replace the time-consuming loop with
a crude estimate that can be computed without holding any mutex.

Even before dict_sys->size was removed in MDEV-13325,
not all memory allocations by the InnoDB data dictionary cache
were being accounted for. One example is foreign key constraints.
Another example is virtual column metadata, starting with 10.2.

on startup innodb is checking whether files "ib_logfileN"
(for N from 1 to 100) exist, and whether they're readable.
A non-existent file aborted the scan.
A directory instead of a file made InnoDB to fail.

Now it treats "directory exists" as "file doesn't exist".

When InnoDB is invoking posix_fallocate() to extend data files, it
was missing a call to fsync() to update the file system metadata.
If file system recovery is needed, the file size could be incorrect.

When the setting innodb_flush_method=O_DIRECT_NO_FSYNC
that was introduced in MariaDB 10.0.11 (and MySQL 5.6) is enabled,
InnoDB would wrongly skip fsync() after extending files.

Furthermore, the merge commit d8b45b0c
inadvertently removed XtraDB error checking for posix_fallocate()
which this fix is restoring.

fil_flush(): Add the parameter bool metadata=false to request that
fil_buffering_disabled() be ignored.

fil_extend_space_to_desired_size(): Invoke fil_flush() with the
extra parameter. After successful posix_fallocate(), invoke
os_file_flush(). Note: The bookkeeping for fil_flush() would not be
updated the posix_fallocate() code path, so the "redundant"
fil_flush() should be a no-op.

thd_destructor_proxy() may miss abort signal if innobase_end() is running
concurrently, which causes server hang in pthread_join() on shutdown.

The problem was that aborting wasn't protected by mutex:
proxy thr: while (!myvar->abort)
end thr: running->abort = 1;
end thr: mysql_cond_broadcast(...);
proxy thr: mysql_cond_wait(...); // nobody to awake it
end thr: pthread_join(...); // waits for proxy thr

Also made main.mysqld_option_err reentrant.

increase to 1M

MDEV-17973: Don't overwrite xtrabackup-v2/mariabackup SST logs by def…

In the function QUICK_RANGE_SELECT::init_ror_merged_scan we create a seperate handler if the handler in
head->file cannot be reused. The flag free_file tells us if we have a seperate handler or not.
There are cases where you might create a handler and then there might be a failure(running ALTER)
and then we have to revert the handler back to the original one. The code does that
but it does not reset the flag 'free_file' in this case.
Also backported f2c41807.

row_drop_table_for_mysql(): Fix a regression introduced in MDEV-16515.
Similar to the follow-up fixes MDEV-16647 and MDEV-17470, we must make
the internal tables of FULLTEXT INDEX immune to kills, to avoid noise
and resource leakage on DROP TABLE or ALTER TABLE. (Orphan internal tables
would be dropped at the next InnoDB startup only.)

server shutdown.

Prior to adding current thd to the global thd list, initialize
thd->mysys_var->current_cond / thd->mysys_var->current_mutex.

Otherwise thd_destructor_proxy can miss the abort condition, which is set
by the shutdown thread.

Problem:
========
MLOG_FILE_WRITE_CRYPT_DATA redo log fails to apply type for
the crypt_data present in the space. While processing the double-write
buffer pages, page fails to decrypt. It leads to warning message.

Fix:
====
Set the type while parsing MLOG_FILE_WRITE_CRYPT_DATA redo log.
If type and length is of invalid type then mark it as corrupted.

Corrects 94d722b6

- There is no need to wait for crypt thread to stop accessing space while
dropping the garbage encrypted tablespace during recover.

Allow table definition cache be bigger than open table cache (due to problem with VIEWs and prepared statements).

Implement according to standard SQL specification 2008.
The check_constraints table is used for fetching metadata about
the constraints defined for tables in all databases.

There were some result files which failed after running mtr.
These files are updated with newly create record with mtr --record.

Poisoning memory after munmap() and friends is totally incorrect as this memory
could be anything.

os_mem_free_large(): remove memory poisoning

If galera.galera_gtid_slave_sst_rsync is repeated more than once it will fail due incorrect GTID position. After stopping SLAVE node reset also GTID_SLAVE_POS variable.

The merge commit d833bb65 did not
correctly merge the commit 03eb1593.

Closes #948

This mutex can be freed when server shuts down (when thread_count goes down to 0)
, but it is still used inside THD::~THD() when Statement_map is destroyed.

The fix is to call Statement_map::reset() at the point where thread_count
is still positive, and avoid locking LOCK_prepared_stmt_count in THD
destructor.

Add the test case. The actual bug was fixed in MDEV-17541.

Closes #811

When performing a hash search via HASH_SEARCH we first look at a key of a node
and then at its pointer to the next node in chain. If we have those in one cache
line instead of a two we reduce memory reads.

I found dict_table_t, fil_space_t and buf_page_t suitable for such improvement.