MDEV-20605 Awaken transaction can miss inserted by other transaction records due to wrong persistent cursor restoration

Backported from 10.5 20e9e804 and
5948d760.

sel_restore_position_for_mysql() moves forward persistent cursor
position after btr_pcur_restore_position() call if cursor relative position
is BTR_PCUR_ON and the cursor points to the record with NOT the same field
values as in a stored record(and some other not important for this case
conditions).

It was done because btr_pcur_restore_position() sets
page_cur_mode_t mode  to PAGE_CUR_LE for cursor->rel_pos ==  BTR_PCUR_ON
before opening cursor. So we are searching for the record less or equal
to stored one. And if the found record is not equal to stored one, then
it is less and we need to move cursor forward.

But there can be a situation when the stored record was purged, but the
new one with the same key but different value was inserted while
row_search_mvcc() was suspended. In this case, when the thread is
awaken, it will invoke sel_restore_position_for_mysql(), which, in turns,
invoke btr_pcur_restore_position(), which will return false because found
record don't match stored record, and
sel_restore_position_for_mysql() will move forward cursor position.

The above can lead to the case when awaken row_search_mvcc() do not see
records inserted by other transactions while it slept. The mtr test case
shows the example how it can be.

The fix is to return special value from persistent cursor restoring
function which would notify its caller that uniq fields of restored
record and stored record are the same, and in this case
sel_restore_position_for_mysql() don't move cursor forward.

Delete-marked records are correctly processed in row_search_mvcc().
Non-unique secondary indexes are "uniquified" by adding the PK, the
index->n_uniq should then be index->n_fields. So there is no need in
additional checks in the fix.

If transaction's readview can't see the changes made in secondary index
record, it requests clustered index record in row_search_mvcc() to check
its transaction id and get the correspondent record version. After this
row_search_mvcc() commits mtr to preserve clustered index latching
order, and starts mtr. Between those mtr commit and start secondary
index pages are unlatched, and purge has the ability to remove stored in
the cursor record, what causes rows duplication in result set for
non-locking reads, as cursor position is restored to the previously
visited record.

To solve this the changes are just switched off for non-locking reads,
it's quite simple solution, besides the changes don't make sense for
non-locking reads.

The more complex and effective from performance perspective solution is
to create mtr savepoint before clustered record requesting and rolling
back to that savepoint after that. See MDEV-27557.

One more solution is to have per-record transaction id for secondary
indexes. See MDEV-17598.

If any of those is implemented, just remove select_lock_type argument in
sel_restore_position_for_mysql().

(cherry picked from commit 66465914)

The code was backported from 10.5 be811386
commit. See that commit message for details.

The sys_var class has the deprecation_substitute member to mark the
deprecated variables. As it's set, the server produces warnings when
these variables are used. However, the plugin has no means to utilize
that functionality.

So, the PLUGIN_VAR_DEPRECATED flag is introduced to set the
deprecation_substitute with the empty string. A non-empty string can
make the warning more informative, but there's no nice way seen to
specify it, and not that needed at the moment.

Fix detection. SSD is when storage does *not* incur a seek penalty.

The .rdiff files were not correctly adjusted in
commit 8f4a3bf0 (MDEV-25057).

convert_error_code_to_mysql(): Use the correct limit FK_MAX_CASCADE_DEL
in the error message. The DICT_FK_MAX_RECURSIVE_LOAD applies to
the number of foreign key constraints in table definitions,
not to the number of rows that are visited while processing
a foreign key constraint.

On FreeBSD, the error message would say "Resource deadlock avoided".
Let us simply replace the error message string in the test.

MDEV-22500 Assertion `thd->killed != 0' failed in ha_maria::enable_indexes

For MDEV-17223 the issue was an assert that didn't take into account that
we could get duplicate key errors when enablling unique indexes.
Fixed by not retrying repair in case of duplicate key error for this
case, which avoids the assert.

For MDEV-22500 I removed the assert, as it's not critical (just a way to
find potential wrong code) and we will anyway get things logged in the
error log if this happens. This case cannot triggered an assert in 10.3
but I verified that it would trigger in 10.5 and that this patch fixes
it.

Some GNU/Linux distributions ship a zlib that is modified to use
the s390x DFLTCC instruction. That modification would essentially
redefine compressBound(sourceLen) as (sourceLen * 16 + 2308) / 8 + 6.

Let us relax the tests for InnoDB ROW_FORMAT=COMPRESSED to cope with
such a weaker compression guarantee.

create_table_info_t::row_size_is_acceptable(): Remove a bogus debug-only
assertion that would fail to hold for the test innodb_zip.bug36169.
The function page_zip_empty_size() may indeed return 0.

Added ability to disable/enable (--disable_view_protocol/--enable_view_protocol) view-protocol in tests.
When the  option "--disable_view_protocol" is used  util connections are closed.
Added new test for checking view-protocol

The rpl.rpl_seconds_behind_master_spike test would sometimes
timeout or take a very long time to complete. This happened
because an MTR DEBUG_SYNC signal would be lost due to a
subsequent call to RESET. I.e., the slave SQL thread would
be paused due to the WAIT_FOR signal being lost, resulting in
either a failed test if the `select master_pos_wait` timeout
occurs first, or a very long run-time if the DBUG_SYNC timeout
occurs first.

The fix ensures that the MTR signal is processed by the slave
SQL thread before issuing the call to RESET

Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>

MDEV-27746 Wrong comparision of BLOB's empty preffix with non-preffixed BLOB causes rows count mismatch for clustered and secondary indexes during non-locking read

row_sel_sec_rec_is_for_clust_rec() treats empty BLOB prefix field in
secondary index as a field equal to any external BLOB field in clustered
index. Row_sel_get_clust_rec_for_mysql::operator() doesn't zerro out
clustered record pointer in row_search_mvcc(), and row_search_mvcc()
thinks that delete-marked secondary index record has visible for
"CHECK TABLE"'s read view old-versioned clustered index record, and
row_scan_index_for_mysql() counts it as a row.

The fix is to execute row_sel_sec_rec_is_for_blob() in
row_sel_sec_rec_is_for_clust_rec() if clustered field contains BLOB's
reference.

The asserion failure was caused by this query

  select /*id=1*/ from t1
  where
   col= ( select /*id=2*/ from ... where corr_cond1
          union
          select /*id=4*/ from ... where corr_cond2)

Here,
- select with id=2 was correlated due to corr_cond1.
- select with id=4 was initially correlated due to corr_cond2, but then
  the optimizer optimized away the correlation, making the select with id=4
  uncorrelated.

However, since select with id=2 remained correlated, the execution had to
re-compute the whole UNION. When it tried to execute select with id=4, it
hit an assertion  (join buffer already free'd).

This is because select with id=4 has freed its execution structures after
it has been executed once. The select is uncorrelated, so it did not expect
it would need to be executed for the second time.

Fixed this by adding this logic in
st_select_lex::optimize_unflattened_subqueries():

  If a member of a UNION is correlated, mark all its members as
  correlated, so that they are prepared to be executed multiple times.

don't let Aria create a table that it cannot open

use the correct check. before invoking handler methods we
need to know that the table was opened, not only created.

Do not assume that subquery Item always present.

Removed all dependencies of command line arguments based on positions in
an array (this kind of code should never have been written).
Instead use option names, which are stable.

Reviewer: Sergei Golubchik