This patch adds a way to override default collations
(or "character set collations") for desired character sets.
The SQL standard says:
> Each collation known in an SQL-environment is applicable to one
> or more character sets, and for each character set, one or more
> collations are applicable to it, one of which is associated with
> it as its character set collation.
In MariaDB, character set collations has been hard-coded so far,
e.g. utf8mb4_general_ci has been a hard-coded character set collation
for utf8mb4.
This patch allows to override (globally per server, or per session)
character set collations, so for example, uca1400_ai_ci can be set as a
character set collation for Unicode character sets
(instead of compiled xxx_general_ci).
The array of overridden character set collations is stored in a new
(session and global) system variable @@character_set_collations and
can be set as a comma separated list of charset=collation pairs, e.g.:
SET @@character_set_collations='utf8mb3=uca1400_ai_ci,utf8mb4=uca1400_ai_ci';
The variable is empty by default, which mean use the hard-coded
character set collations (e.g. utf8mb4_general_ci for utf8mb4).
The variable can also be set globally by passing to the server startup command
line, and/or in my.cnf.
Allow ALTER TABLE ... IMPORT TABLESPACE without creating the table
followed by discarding the tablespace.
That is, assuming we want to import table t1 to t2, instead of
CREATE TABLE t2 LIKE t1;
ALTER TABLE t2 DISCARD TABLESPACE;
FLUSH TABLES t1 FOR EXPORT;
--copy_file $MYSQLD_DATADIR/test/t1.cfg $MYSQLD_DATADIR/test/t2.cfg
--copy_file $MYSQLD_DATADIR/test/t1.ibd $MYSQLD_DATADIR/test/t2.ibd
UNLOCK TABLES;
ALTER TABLE t2 IMPORT TABLESPACE;
We can simply do
FLUSH TABLES t1 FOR EXPORT;
--copy_file $MYSQLD_DATADIR/test/t1.cfg $MYSQLD_DATADIR/test/t2.cfg
--copy_file $MYSQLD_DATADIR/test/t1.frm $MYSQLD_DATADIR/test/t2.frm
--copy_file $MYSQLD_DATADIR/test/t1.ibd $MYSQLD_DATADIR/test/t2.ibd
UNLOCK TABLES;
ALTER TABLE t2 IMPORT TABLESPACE;
We achieve this by creating a "stub" table in the second scenario
while opening the table, where t2 does not exist but needs to import
from t1. The "stub" table is similar to a table that is created but
then instructed to discard its tablespace.
We include tests with various row formats, encryption, with indexes
and auto-increment.
Adding virtual methods to class Schema:
make_item_func_replace()
make_item_func_substr()
make_item_func_trim()
This is a non-functional preparatory change for MDEV-27744.
This patch is the result of running
run-clang-tidy -fix -header-filter=.* -checks='-*,modernize-use-equals-default' .
Code style changes have been done on top. The result of this change
leads to the following improvements:
1. Binary size reduction.
* For a -DBUILD_CONFIG=mysql_release build, the binary size is reduced by
~400kb.
* A raw -DCMAKE_BUILD_TYPE=Release reduces the binary size by ~1.4kb.
2. Compiler can better understand the intent of the code, thus it leads
to more optimization possibilities. Additionally it enabled detecting
unused variables that had an empty default constructor but not marked
so explicitly.
Particular change required following this patch in sql/opt_range.cc
result_keys, an unused template class Bitmap now correctly issues
unused variable warnings.
Setting Bitmap template class constructor to default allows the compiler
to identify that there are no side-effects when instantiating the class.
Previously the compiler could not issue the warning as it assumed Bitmap
class (being a template) would not be performing a NO-OP for its default
constructor. This prevented the "unused variable warning".
The reason for this is that we call file->index_flags(index, 0, 1)
multiple times in best_access_patch()when optimizing a table.
For example, in InnoDB, the calls is not trivial (4 if's and 2 assignments)
Now the function is inlined and is just a memory reference.
Other things:
- handler::is_clustering_key() and pk_is_clustering_key() are now inline.
- Added TABLE::can_use_rowid_filter() to simplify some code.
- Test if we should use a rowid_filter only if can_use_rowid_filter() is
true.
- Added TABLE::is_clustering_key() to avoid a memory reference.
- Simplify some code using the fact that HA_KEYREAD_ONLY is true implies
that HA_CLUSTERED_INDEX is false.
- Added DBUG_ASSERT to TABLE::best_range_rowid_filter() to ensure we
do not call it with a clustering key.
- Reorginized elements in struct st_key to get better memory alignment.
- Updated ha_innobase::index_flags() to not have
HA_DO_RANGE_FILTER_PUSHDOWN for clustered index
Specifically:
Revert "MDEV-29664 Assertion `!n_mysql_tables_in_use' failed in innobase_close_connection"
This reverts commit ba875e9396.
Revert "MDEV-29620 Assertion `next_insert_id == 0' failed in handler::ha_external_lock"
This reverts commit aa08a7442a.
Revert "MDEV-29628 Memory leak after CREATE OR REPLACE with foreign key"
This reverts commit c579d66ba6.
Revert "MDEV-29609 create_not_windows test fails with different result"
This reverts commit cb583b2f1b.
Revert "MDEV-29544 SIGSEGV in HA_CREATE_INFO::finalize_locked_tables"
This reverts commit dcd66c3814.
Revert "MDEV-28933 CREATE OR REPLACE fails to recreate same constraint name"
This reverts commit cf6c517632.
Revert "MDEV-28933 Moved RENAME_CONSTRAINT_IDS to include/sql_funcs.h"
This reverts commit f1e1c1335b.
Revert "MDEV-28956 Locking is broken if CREATE OR REPLACE fails under LOCK TABLES"
This reverts commit a228ec80e3.
Revert "MDEV-25292 gcol.gcol_bugfixes --ps fix"
This reverts commit 24fff8267d.
Revert "MDEV-25292 Disable atomic replace for slave-generated or-replace"
This reverts commit 2af15914cb.
Revert "MDEV-25292 backup_log improved"
This reverts commit 34398a20b5.
Revert "MDEV-25292 Atomic CREATE OR REPLACE TABLE"
This reverts commit 93c8252f02.
Revert "MDEV-25292 Table_name class for (db, table_name, alias)"
This reverts commit d145dda9c7.
Revert "MDEV-25292 ha_table_exists() cleanup and improvement"
This reverts commit 409b8a86de.
Revert "MDEV-25292 Cleanups"
This reverts commit 595dad83ad.
Revert "MDEV-25292 Refactoring: moved select_field_count into Alter_info."
This reverts commit f02af1d229.
Atomic CREATE OR REPLACE allows to keep an old table intact if the
command fails or during the crash. That is done through creating
a table with a temporary name and filling it with the data
(for CREATE OR REPLACE .. SELECT), then renaming the original table
to another temporary (backup) name and renaming the replacement table
to original table. The backup table is kept until the last chance of
failure and if that happens, the replacement table is thrown off and
backup recovered. When the command is complete and logged the backup
table is deleted.
Atomic replace algorithm
Two DDL chains are used for CREATE OR REPLACE:
ddl_log_state_create (C) and ddl_log_state_rm (D).
1. (C) Log CREATE_TABLE_ACTION of TMP table (drops TMP table);
2. Create new table as TMP;
3. Do everything with TMP (like insert data);
finalize_atomic_replace():
4. Link chains: (D) is executed only if (C) is closed;
5. (D) Log DROP_ACTION of BACKUP;
6. (C) Log RENAME_TABLE_ACTION from ORIG to BACKUP (replays BACKUP -> ORIG);
7. Rename ORIG to BACKUP;
8. (C) Log CREATE_TABLE_ACTION of ORIG (drops ORIG);
9. Rename TMP to ORIG;
finalize_ddl() in case of success:
10. Close (C);
11. Replay (D): BACKUP is dropped.
finalize_ddl() in case of error:
10. Close (D);
11. Replay (C):
1) ORIG is dropped (only after finalize_atomic_replace());
2) BACKUP renamed to ORIG (only after finalize_atomic_replace());
3) drop TMP.
If crash happens (C) or (D) is replayed in reverse order. (C) is
replayed if crash happens before it is closed, otherwise (D) is
replayed.
Temporary table for CREATE OR REPLACE
Before dropping "old" table, CREATE OR REPLACE creates "tmp" table.
ddl_log_state_create holds the drop of the "tmp" table. When
everything is OK (data is inserted, "tmp" is ready) ddl_log_state_rm
is written to replace "old" with "tmp". Until ddl_log_state_create
is closed ddl_log_state_rm is not executed.
After the binlogging is done ddl_log_state_create is closed. At that
point ddl_log_state_rm is executed and "tmp" is replaced with
"old". That is: final rename is done by the DDL log.
With that important role of DDL log for CREATE OR REPLACE operation
replay of ddl_log_state_rm must fail at the first hit error and
print the error message if possible. F.ex. foreign key error is
discovered at this phase: InnoDB rejects to drop the "old" table and
returns corresponding foreign key error code.
Additional notes
- CREATE TABLE without REPLACE is not affected by this commit.
- Engines having HTON_EXPENSIVE_RENAME flag set are not affected by
this commit.
- CREATE TABLE .. SELECT XID usage is fixed and now there is no need
to log DROP TABLE via DDL_CREATE_TABLE_PHASE_LOG (see comments in
do_postlock()). XID is now correctly updated so it disables
DDL_LOG_DROP_TABLE_ACTION. Note that binary log is flushed at the
final stage when the table is ready. So if we have XID in the
binary log we don't need to drop the table.
- Three variations of CREATE OR REPLACE handled:
1. CREATE OR REPLACE TABLE t1 (..);
2. CREATE OR REPLACE TABLE t1 LIKE t2;
3. CREATE OR REPLACE TABLE t1 SELECT ..;
- Test case uses 6 combinations for engines (aria, aria_notrans,
myisam, ib, lock_tables, expensive_rename) and 2 combinations for
binlog types (row, stmt). Combinations help to check differences
between the results. Error failures are tested for the above three
variations.
- expensive_rename tests CREATE OR REPLACE without atomic
replace. The effect should be the same as with the old behaviour
before this commit.
- Triggers mechanism is unaffected by this change. This is tested in
create_replace.test.
- LOCK TABLES is affected. Lock restoration must be done after "rm"
chain is replayed.
- Moved ddl_log_complete() from send_eof() to finalize_ddl(). This
checkpoint was not executed before for normal CREATE TABLE but is
executed now.
- CREATE TABLE will now rollback also if writing to the binary
logging failed. See rpl_gtid_strict.test
Rename and drop via DDL log
We replay ddl_log_state_rm to drop the old table and rename the
temporary table. In that case we must throw the correct error
message if ddl_log_revert() fails (f.ex. on FK error).
If table is deleted earlier and not via DDL log and the crash
happened, the create chain is not closed. Linked drop chain is not
executed and the new table is not installed. But the old table is
already deleted.
ddl_log.cc changes
Now we can place action before DDL_LOG_DROP_INIT_ACTION and it will
be replayed after DDL_LOG_DROP_TABLE_ACTION.
report_error parameter for ddl_log_revert() allows to fail at first
error and print the error message if possible.
ddl_log_execute_action() now can print error message.
Since we now can handle errors from ddl_log_execute_action() (in
case of non-recovery execution) unconditional setting "error= TRUE"
is wrong (it was wrong anyway because it was overwritten at the end
of the function).
On XID usage
Like with all other atomic DDL operations XID is used to avoid
inconsistency between master and slave in the case of a crash after
binary log is written and before ddl_log_state_create is closed. On
recovery XIDs are taken from binary log and corresponding DDL log
events get disabled. That is done by
ddl_log_close_binlogged_events().
On linking two chains together
Chains are executed in the ascending order of entry_pos of execute
entries. But entry_pos assignment order is undefined: it may assign
bigger number for the first chain and then smaller number for the
second chain. So the execution order in that case will be reverse:
second chain will be executed first.
To avoid that we link one chain to another. While the base chain
(ddl_log_state_create) is active the secondary chain
(ddl_log_state_rm) is not executed. That is: only one chain can be
executed in two linked chains.
The interface ddl_log_link_chains() was done in "MDEV-22166
ddl_log_write_execute_entry() extension".
More on CREATE OR REPLACE .. SELECT
We use create_and_open_tmp_table() like in ALTER TABLE to create
temporary TABLE object (tmp_table is (NON_)TRANSACTIONAL_TMP_TABLE).
After we created such TABLE object we use create_info->tmp_table()
instead of table->s->tmp_table when we need to check for
parser-requested tmp-table.
External locking is required for temporary table created by
create_and_open_tmp_table(). F.ex. that disables logging for Aria
transactional tables and without that (when no mysql_lock_tables()
is done) it cannot work correctly.
For making external lock the patch requires Aria table to work in
non-transactional mode. That is usually done by
ha_enable_transaction(false). But we cannot disable transaction
completely because: 1. binlog rollback removes pending row events
(binlog_remove_pending_rows_event()). The row events are added
during CREATE .. SELECT data insertion phase. 2. replication slave
highly depends on transaction and cannot work without it.
So we put temporary Aria table into non-transactional mode with
"thd->transaction->on hack". See comment for on_save variable.
Note that Aria table has internal_table mode. But we cannot use it
because:
if (!internal_table)
{
mysql_mutex_lock(&THR_LOCK_myisam);
old_info= test_if_reopen(name_buff);
}
For internal_table test_if_reopen() is not called and we get a new
MARIA_SHARE for each file handler. In that case duplicate errors are
missed because insert and lookup in CREATE .. SELECT is done via two
different handlers (see create_lookup_handler()).
For temporary table before dropping TABLE_SHARE by
drop_temporary_table() we must do ha_reset(). ha_reset() releases
storage share. Without that the share is kept and the second CREATE
OR REPLACE .. SELECT fails with:
HA_ERR_TABLE_EXIST (156): MyISAM table '#sql-create-b5377-4-t2' is
in use (most likely by a MERGE table). Try FLUSH TABLES.
HA_EXTRA_PREPARE_FOR_DROP also removes MYISAM_SHARE, but that is
not needed as ha_reset() does the job.
ha_reset() is usually done by
mark_tmp_table_as_free_for_reuse(). But we don't need that mechanism
for our temporary table.
Atomic_info in HA_CREATE_INFO
Many functions in CREATE TABLE pass the same parameters. These
parameters are part of table creation info and should be in
HA_CREATE_INFO (or whatever). Passing parameters via single
structure is much easier for adding new data and
refactoring.
InnoDB changes (revised by Marko Mäkelä)
row_rename_table_for_mysql(): Specify the treatment of FOREIGN KEY
constraints in a 4-valued enum parameter. In cases where FOREIGN KEY
constraints cannot exist (partitioned tables, or internal tables of
FULLTEXT INDEX), we can use the mode RENAME_IGNORE_FK.
The mod RENAME_REBUILD is for any DDL operation that rebuilds the
table inside InnoDB, such as TRUNCATE and native ALTER TABLE
(or OPTIMIZE TABLE). The mode RENAME_ALTER_COPY is used solely
during non-native ALTER TABLE in ha_innobase::rename_table().
Normal ha_innobase::rename_table() will use the mode RENAME_FK.
CREATE OR REPLACE will rename the old table (if one exists) along
with its FOREIGN KEY constraints into a temporary name. The replacement
table will be initially created with another temporary name.
Unlike in ALTER TABLE, all FOREIGN KEY constraints must be renamed
and not inherited as part of these operations, using the mode RENAME_FK.
dict_get_referenced_table(): Let the callers convert names when needed.
create_table_info_t::create_foreign_keys(): CREATE OR REPLACE creates
the replacement table with a temporary name table, so for
self-references foreign->referenced_table will be a table with
temporary name and charset conversion must be skipped for it.
Reviewed by:
Michael Widenius <monty@mariadb.org>
Changing the error messages in a statement like this:
CREATE DATABASE db1
COLLATE utf8mb4_bin
CHARACTER SET utf8mb4
CHARACTER SET latin1;
from
COLLATION 'utf8mb4_bin' is not valid for CHARACTER SET 'latin1'
to a more expected:
Conflicting declarations: 'CHARACTER SET utf8mb4' and 'CHARACTER SET latin1'
In order to do this:
- Adding a new type TYPE_CHARACTER_SET_COLLATE_EXACT into
Lex_exact_charset_extended_collation_attrs_st
- Removing m_had_charset_exact from its descendant class
Lex_extended_charset_extended_collation_attrs_st
Additional cleanup:
- Changing methods in Lex_exact_charset_extended_collation_attrs_st
set_charset(), set_charset_collate_default(), set_charset_collate_binary()
to get Lex_exact_charset instead CHARSET_INFO as a parameter,
to guarantee that the argument is only CHARACTER SET and does not have
any COLLATE clauses yet. This change is not directly related to
the error message change.
- Renaming Lex_charset_collation_st to
Lex_exact_charset_extended_collation_attrs_st
- Renaming Lex_explicit_charset_opt_collate to
Lex_exact_charset_opt_extended_collate
- Renaming their methods charset_collation() to charset_info(),
so the name clearly tells that it returns CHARSET_INFO.
Soon we'll have new classes (e.g. Lex_exact_collation) and
methods returning Lex_exact_collation. So the old name would be
confusing about the return type.
- Adding data type aliases:
using Lex_column_charset_collation_attrs_st = Lex_charset_collation_st;
using Lex_column_charset_collation_attrs = Lex_charset_collation;
and using them all around the code (except lex_charset.*)
instead of the original names.
- Renaming Lex_field_type_st::lex_charset_collation()
to charset_collation_attrs()
- Renaming Column_definition::set_lex_charset_collation()
to set_charset_collation_attrs()
- Renaming Column_definition::lex_charset_collation()
to charset_collation_attrs()
Rationale:
The name "Lex_charset_collation" was a not very good name.
It does not tell details about its properties:
1. if the charset is optional (yes)
2. if the collation is optional (yes)
3. if the charset can be exact (yes) or context (no)
4. if the collation can be: exact (yes) or context (yes)
5. if the clauses can be repeated multiple times (yes)
We'll need a few new data types soon with different properties.
For example, to fix MDEV-27896 and MDEV-27782, we'll need a new
data type which is very like Lex_charset_collation, but additionally
supports CHARACTER SET DEFAULT (which is allowed on table and database level,
but is not allowed on the column level yet), i.e. with:
"the charset can be exact (yes) or context (yes)" in N3.
So we'll have to rename Lex_charset_collation to something else,
e.g.: Lex_exact_charset_extended_collation_attrs,
and add a new data type:
e.g. Lex_extended_charset_extended_collation_attrs
Also, we'll possibly allow CHARACTER SET DEFAULT at the column level for
consistency with other places. So the storge on the column level can change:
- from Lex_exact_charset_extended_collation_attrs
- to Lex_extended_charset_extended_collation_attrs
Adding the aliases introduces a convenient abstraction against
upcoming renames and c++ data type changes.
The cause of the bug is overflow of uint16 KEY_PART_INFO::length and/or
uint16 KEY_PART_INFO::store_length. The solution is to increase the size
of those variables to the 'uint' type (which is 32-bit long)
This patch also fixes:
MDEV-27690 Crash on `CHARACTER SET csname COLLATE DEFAULT` in column definition
MDEV-27853 Wrong data type on column `COLLATE DEFAULT` and table `COLLATE some_non_default_collation`
MDEV-28067 Multiple conflicting column COLLATE clauses are not rejected
MDEV-28118 Wrong collation of `CAST(.. AS CHAR COLLATE DEFAULT)`
MDEV-28119 Wrong column collation on MODIFY + CONVERT
This is used by InnoDB to detect if CREATE...SELECT is used
Other things:
- Changed InnoDB to use thd_ddl_options()
- Removed lock checking code for create...select (Approved by Marko)
This commit implements the standard SQL extension
OFFSET start { ROW | ROWS }
[FETCH { FIRST | NEXT } [ count ] { ROW | ROWS } { ONLY | WITH TIES }]
To achieve this a reserved keyword OFFSET is introduced.
The general logic for WITH TIES implies:
1. The number of rows a query returns is no longer known during optimize
phase. Adjust optimizations to no longer consider this.
2. During end_send make use of an "order Cached_item"to compare if the
ORDER BY columns changed. Keep returning rows until there is a
change. This happens only after we reached the row limit.
3. Within end_send_group, the order by clause was eliminated. It is
still possible to keep the optimization of using end_send_group for
producing the final result set.
Replace
* select_lex::offset_limit
* select_lex::select_limit
* select_lex::explicit_limit
with select_lex::Lex_select_limit
The Lex_select_limit already existed with the same elements and was used in
by the yacc parser.
This commit is in preparation for FETCH FIRST implementation, as it
simplifies a lot of the code.
Additionally, the parser is simplified by making use of the stack to
return Lex_select_limit objects.
Cleanup of init_query() too. Removes explicit_limit= 0 as it's done a bit later
in init_select() with limit_params.empty()
Adds an implementation for SELECT ... FOR UPDATE SKIP LOCKED /
SELECT ... LOCK IN SHARED MODE SKIP LOCKED
This is implemented only InnoDB at the moment, not in RockDB yet.
This adds a new hander flag HA_CAN_SKIP_LOCKED than
will be used when the storage engine advertises the flag.
When a storage engine indicates this flag it will get
TL_WRITE_SKIP_LOCKED and TL_READ_SKIP_LOCKED transaction types.
The Lex structure has been updated to store both the FOR UPDATE/LOCK IN
SHARE as well as the SKIP LOCKED so the SHOW CREATE VIEW
implementation is simplier.
"SELECT FOR UPDATE ... SKIP LOCKED" combined with CREATE TABLE AS or
INSERT.. SELECT on the result set is not safe for STATEMENT based
replication. MIXED replication will replicate this as row based events."
Thanks to guidance from Facebook commit
193896c466
This helped verify basic test case, and components that need implementing
(even though every part was implemented differently).
Thanks Marko for guidance on simplier InnoDB implementation.
Reviewers: Marko, Monty
This feature adds the functionality of ignorability for indexes.
Indexes are not ignored be default.
To control index ignorability explicitly for a new index,
use IGNORE or NOT IGNORE as part of the index definition for
CREATE TABLE, CREATE INDEX, or ALTER TABLE.
Primary keys (explicit or implicit) cannot be made ignorable.
The table INFORMATION_SCHEMA.STATISTICS get a new column named IGNORED that
would store whether an index needs to be ignored or not.
The issue happens when the secondary keys are extended with primary
key parts. Inside the function TABLE_SHARE::init_from_binary_frm_image()
adds the length bytes for the primary key key parts to the length of the
secondary key. This is not needed because when the extended keys are
used we recalculate the length for the used key parts.
Also removed TABLE_SHARE::total_key_length as it is not used in the code
Apporved-by: Monty <monty@mariadb.org>
The data member tv_usec of the struct timeval is declared as suseconds_t
on MacOS. Size of suseconds_t is 4 bytes. On the other hand, size of ulong
is 8 bytes on 64-bit MacOS, so attempt to assign a value of wider type
(usec) to a value (tv_usec) of narrower type leads to error.
- Adding optional qualifiers to data types:
CREATE TABLE t1 (a schema.DATE);
Qualifiers now work only for three pre-defined schemas:
mariadb_schema
oracle_schema
maxdb_schema
These schemas are virtual (hard-coded) for now, but may turn into real
databases on disk in the future.
- mariadb_schema.TYPE now always resolves to a true MariaDB data
type TYPE without sql_mode specific translations.
- oracle_schema.DATE translates to MariaDB DATETIME.
- maxdb_schema.TIMESTAMP translates to MariaDB DATETIME.
- Fixing SHOW CREATE TABLE to use a qualifier for a data type TYPE
if the current sql_mode translates TYPE to something else.
The above changes fix the reported problem, so this script:
SET sql_mode=ORACLE;
CREATE TABLE t2 AS SELECT mariadb_date_column FROM t1;
is now replicated as:
SET sql_mode=ORACLE;
CREATE TABLE t2 (mariadb_date_column mariadb_schema.DATE);
and the slave can unambiguously treat DATE as the true MariaDB DATE
without ORACLE specific translation to DATETIME.
Similar,
SET sql_mode=MAXDB;
CREATE TABLE t2 AS SELECT mariadb_timestamp_column FROM t1;
is now replicated as:
SET sql_mode=MAXDB;
CREATE TABLE t2 (mariadb_timestamp_column mariadb_schema.TIMESTAMP);
so the slave treats TIMESTAMP as the true MariaDB TIMESTAMP
without MAXDB specific translation to DATETIME.
* The overlaps check is implemented on a handler level per row command.
It creates a separate cursor (actually, another handler instance) and
caches it inside the original handler, when ha_update_row or
ha_insert_row is issued. Cursor closes on unlocking the handler.
* Containing the same key in index means unique constraint violation
even in usual terms. So we fetch left and right neighbours and check
that they have same key prefix, excluding from the key only the period part.
If it doesnt match, then there's no such neighbour, and the check passes.
Otherwise, we check if this neighbour intersects with the considered key.
* The check does not introduce new error and fails with ER_DUPP_KEY error.
This might break REPLACE workflow and should be fixed separately
