When starting to do a full table/index scan without a WHERE or JOIN
condition, tell the storage engine so and the corresponding
ulong-truncated LIMIT.
Include an innodb implementation: added an innodb switch
table_lock_on_full_scan, so that when the switch is on, on receiving
the full scan signal from the sql layer, if the truncated LIMIT is
ULONG_MAX (likely no LIMIT), attempt to acquire a table lock.
Updated tests that have different results with the switch on.
The three deadlock_*_race tests cannot reach their DEBUG_SYNC race
under a table lock (it degenerates to a timeout), and the three I_S
tests only restate a lock-mode change already covered
by innodb_full_scan.test.
(Comment and code edited by Sergei Petrunia <sergey@mariadb.com> and
Thirunarayanan Balathandayuthapani <thiru@mariadb.com>)
This is regression caused by MDEV-28750 commit 1f349968.
In multi-table update table list could contain tables
that are not yet opened because update does not really
change them. This can happen e.g. when update changes
table that is referenced by foreign key by table that
is not part of multi-table update.
Fixed by first checking is wsrep write set size limited.
If it is not multi-table update can continue normally.
If write set size is limited then check has update
updated both transactional and non-transactional tables
and those tables that have not yet been opened can be
safely skipped as they are not updated.
Analysis:
OLD_VALUE() swapped only field->ptr, leaving null_ptr pointing to the
current record. This caused incorrect NULL results.
Fix:
Store null_ptr_old for record[1] and swap it together with ptr to
preserve correct NULL semantics.
of type 'multi_update' in sql/sql_update.cc
| Sql_cmd_update::update_single_table
Analysis:
the 'result' object was being incorrectly used which maybe of the type
multi_update.This caused UBSAN error due to an invalid downcast in
Sql_cmd_update::update_single_table().
Fix:
Introduce a dedicated returning_result object for handling RETURNING output
instead of reusing result. This ensures the correct result handler is used
and avoids unsafe casts.
The patch introduces the OLD_VALUE() expression to reference the value
of a column before it was updated. The parser is extended to support
RETURNING and OLD_VALUE(), and RETURNING expressions are stored in a
separate returning_list in SELECT_LEX with independent wildcard tracking.
RETURNING is rejected for multi-table UPDATE.
During setup of RETURNING fields, THD::is_setting_returning is used
when resolving fields, particularly for updates through views.
When resolving view fields, Item_direct_view_ref may point to the
view's item_list, losing the information about whether the value
should be old or new. The original item in returning_list still
contains the correct is_old_value_reference flag, which is copied
back to the resolved item.
OLD_VALUE() is implemented by extending Item_field with a new
Item_old_field class. Item_field::set_field() initializes
Field::ptr_old to the corresponding location in record[1],
which stores the old row during UPDATE execution.
When sending result rows, Item_old_field::send() temporarily switches
the field pointer from record[0] (current row) to ptr_old so
OLD_VALUE() returns the value before the update.
The UPDATE execution path is modified to send a result set when
RETURNING is present instead of an OK packet.
Reason:
=======
Following the changes in MDEV-38734, the server no longer marks
all indexed virtual columns during an UPDATE operation.
Consequently, ha_innobase::update() populates the upd_t vector
with old_vrow but omits the actual data for these virtual columns.
Despite this omission, trx_undo_page_report_modify() continues to
write metadata for indexed virtual columns into the undo log. Because
the actual values are missing from the update vector, the undo log
entry is recorded without the historical data for these columns.
When the purge thread processes the undo log to reconstruct a
previous record state for MVCC, it identifies an indexed virtual
column but finds no associated data.
The purge thread incorrectly interprets this missing data as a NULL
value, rather than a "missing/unrecorded" value. The historical
record is reconstructed with an incorrect NULL for the virtual column.
This causes the purge thread to incorrectly identify and purge
records that are not actually delete-marked, leading to abort
of server.
Solution:
=========
ha_innobase::column_bitmaps_signal(): Revert the column-marking
logic to the state prior to commit a4e4a56720, ensuring all
indexed virtual columns are unconditionally marked during an UPDATE.
The previous "optimization" attempted to manually detect indexed
column changes before marking virtual columns. The manual check
for indexed column modifications is redundant. InnoDB already
provides the UPD_NODE_NO_ORD_CHANGE flag within row_upd_step().
This flag is being used in trx_undo_page_report_modify() and
trx_undo_read_undo_rec() should log or read virtual column values.
Refactored column_bitmaps_signal() to accept a mark_for_update
parameter that controls when indexed virtual columns are marked.
TABLE::mark_columns_needed_for_update() is the only place that needs
mark_for_update=true because only UPDATE operations need to mark
indexed virtual columns for InnoDB's undo logging mechanism.
INSERT operation is already handled by
TABLE::mark_virtual_columns_for_write(insert_fl=true).
Even the commit a4e4a56720 changes are
going to affect TABLE::mark_virtual_column_for_write(false) and
It is called during UPDATE operation, and that's when
column_bitmaps_signal() needs to mark indexed virtual columns.
Online DDL has separate code path which is handled by
row_log_mark_virtual_cols() for all DML operations
Problem was that in multi-table update that contains tables that are not
transactional and tables that are transactional error handling does not
work correctly if write set size is limited. Because, Galera
replication for MyISAM is experimental it is better to avoid
multi-table updates in this case.
Fixed by not allowing multi-table updates if statement contains
non transactional and transactional tables and write set size
is limited.
ft_handler isn't getting initialized for subqueries inside explain
delete/update queries. However, ft_handler is accessed inside ha_ft_read(),
and is the reason for NULL pointer exception.
This is not the case with non-explain delete/update queries, as
well as explain/non-explain select queries.
Follow the approach the SELECT statements are using in
JOIN::optimize_constant_subqueries(): remove SELECT_DESCRIBE
flag when invoking optimization of constant subqueries.
Single-table UPDATE/DELETEs have SELECT_LEX but don't have JOIN.
So, we make optimize_constant_subqueries() not to be a member
of JOIN class, and instead move it to SELECT_LEX, and then
invoke it from single-table UPDATE/DELETE as well as for SELECT queries.
in SIMULTANEOUS_ASSIGNMENT there is no need to switch value items
to new nullable copies of table Field's - they must refer to old
values in the row, which can never be null anyway.
skipping this redundant step simplifies moving field to record[1]
and back in fill_record()
We extend from the SQL standard to match the functionality of other
databases that allow the inclusion of a CTE definition prior to update
and delete statements.
These CTEs are currently read only, like other derived tables, so
cannot have their columns updated in updates set clause, nor have rows
removed in the delete statement.
Approved by: Oleksandr Byelkin (sanja@mariadb.com)
after 633417308f (MDEV-37312) lookup_handler is locked with F_WRLCK,
because it may be used for deleting rows.
And lookup_handler is locked with F_WRLCK after prune_partitions(),
but the main handler is locked before, and might expects all
partitions to be in the read least, non-pruned.
Let's prepare the lookup handler before prune_partitions().
main/statistics_json.result is updated for f8ba5ced55 (MDEV-36099)
The test uses 'delete from t1' in many places and then populates
the table again. The natural order of rows in a MyISAM table is well
defined and the test was implicitly relying on that.
before f8ba5ced55 delete was deleting rows one by one, using
ha_myisam::delete_row() because the connection was stuck in rbr mode.
This caused rows to be shown in the reverse insertion order (because of
the delete link list).
MDEV-36099 fixes this bug and the server now correctly uses
ha_myisam::delete_all_rows(). This makes rows to be shown in the
insertion order as expected.
mysql_update() aborts if SQL_SELECT::check_quick() fails.
SQL_SELECT::check_quick() fails when thd->killed is set.
Thus, mysql_update() must also test thd->killed to know how to
terminate - normally (impossible where) or abnormally.
in 11.4 multi_update::prepare() is called both for single and multi update.
as it's invoked before lock_tables(), it cannot do prepare_for_insert(),
which calls external_lock() and only can be used on an already locked table
Also expand vcol field index coverings to include indexes covering all
the fields in the expression. The reasoning goes as follows: let f(c1,
c2, ..., cn) be a function on applied to columns c1, c2, ..., cn, if
f(...) is covered by an index, so should vc whose expression is
f(...).
For example, if t.vf = t.c1 + t.c2, and t has three indexes (vf), (c1,
c2), (c1).
Before this change, vf's index covering is a singleton {(vf)}. Let's call
that the "conventional" index covering.
After this change vf's index covering is now {(vf), (c1, c2)}, since
(c1, c2) covers both c1 and c2. Let's call (c1, c2) in this case the
"extra" covering.
With the coverings updated, when an index in the "extra" covering is
chosen for keyread, the vcol also needs to be calculated. In this case
we mark vcol in the table read_set, and ensure it is computed.
With these changes, we see various improvements, including from using
full table scan + filesort to full index scan + filesort when ORDER BY
an indexed vcol (here vc = c + 1 is a vcol and both c and vc are
indexes):
explain select c + 1 from t order by vc;
id select_type table type possible_keys key key_len ref rows Extra
-1 SIMPLE t ALL NULL NULL NULL NULL 10000 Using filesort
+1 SIMPLE t index NULL c 5 NULL 10000 Using index; Using filesort
The substitutions are followed updates to all_fields which include a
copy of the ORDER BY/GROUP BY item pointers, as well as corresponding
updates to ref_pointer_array so that the all_fields and
ref_pointer_array remain in sync.
Another, related change is the recomputation of table index covering
on substitutions. It not only reflects the correct table index
covering after the substitutions, but also improve executions where
the vcol index can be chosen, such as this example (here vc = c + 1
and vc is the only index in the table), from full table scan +
filesort to full index scan:
select vc from t order by c + 1;
We do it in SELECT as well as in single table DELETE/UPDATE.
When processing queries like
INSERT INTO t1 (..) SELECT .. FROM t1, t2 ...,
there is a single query block (i.e., a single SELECT_LEX) for both INSERT and
SELECT parts. During hints resolution, when hints are attached to particular
TABLE_LIST's, the search is performed by table name across the whole
query block.
So, if a table mentioned in an optimizer hint is present in the INSERT part,
the hint is attached to the that table. This is obviously wrong as
optimizer hints are supposed to only affect the SELECT part of
an INSERT..SELECT clause.
This commit disables possible attaching hints to tables in the INSERT part
and fixes some other bugs related to INSERT..SELECT statements processing
It places a limit N (a timeout value in milliseconds) on how long
a statement is permitted to execute before the server terminates it.
Syntax:
SELECT /*+ MAX_EXECUTION_TIME(milliseconds) */ ...
Only top-level SELECT statements support the hint.
MDEV-36563 Assertion `!mysql_bin_log.is_open()' failed in
THD::mark_tmp_table_as_free_for_reuse
The purpose of this commit is to ensure that creation and changes of
temporary tables are properly and predicable logged to the binary
log. It also fixes some bugs where ROW logging was used in MIXED mode,
when STATEMENT would be a better (and expected) choice.
In this comment STATEMENT stands for logging to binary log in
STATEMENT format, MIXED stands for MIXED binlog format and ROW for ROW
binlog format.
New rules for logging of temporary tables
- CREATE of temporary tables are now by default binlogged only if
STATEMENT binlog format is used. If it is binlogged, 1 is stored in
TABLE_SHARE->table_creation_was_logged. The user can change this
behavior by setting create_temporary_table_binlog_formats to
MIXED,STATEMENT in which case the create is logged in statement
format also in MIXED mode (as before).
- Changes to temporary tables are only binlogged if and only if
the CREATE was logged. The logging happens under STATEMENT or MIXED.
If binlog_format=ROW, temporary table changes are not binlogged. A
temporary table that are changed under ROW are marked as 'not up to
date in binlog' and no future row changes are logged. Any usage of
this temporary table will force row logging of other tables in any
future statements using the temporary table to be row logged.
- DROP TEMPORARY is binlogged only of the CREATE was binlogged.
Changes done:
- Row logging is forced for any statement using temporary tables that
are not up to date in the binary log.
(Before the row logging was forced if the user has a temporary table)
- If there is any changes to the temporary table that is not binlogged,
the table is marked as not up to date.
- TABLE_SHARE->table_creation_was_logged has a new definition for
temporary tables:
0 Table creating was not logged to binary log
1 Table creating was logged to binary log and table is up to date.
2 Table creating was logged to binary log but some changes where
not logged to binary log.
Table is not up to date in binary log is defined as value 0 or 2.
- If a multi-table-update or multi-table-delete fails then
all updated temporary tables are marked as not up to date.
- Enforce row logging if the query is using temporary tables
that are not up to date.
Before row logging was enforced if the user had any
temporary tables.
- When dropping temporary tables use IF EXISTS. This ensures
that slave will not stop if it had crashed and lost the
temporary tables.
- Remove comment and version from DROP /*!4000 TEMPORARY.. generated when
a connection closes that has open temporary tables. Added 'generated by
server' at the end of the DROP.
Bugs fixed:
- When using temporary tables with commands that forced row based,
like INSERT INTO temporary_table VALUES (UUID()), this was never
logged which causes the temporary table to be inconsistent on
master and slave.
- Used binlog format is now clearly defined. It is now only depending
on the current binlog_format and the tables used.
Before it was depending on the user had ANY temporary tables and
the state of 'current_stmt_binlog_format' set by previous queries.
This also caused temporary tables to be logged to binary log in
some cases.
- CREATE TABLE t1 LIKE not_logged_temporary_table caused replication
to stop.
- Rename of not binlogged temporary tables where binlogged to binary log
which caused replication to stop.
Changes in behavior:
- By default create_temporary_table_binlog_formats=STATEMENT, which
means that CREATE TEMPORARY is not logged to binary log under MIXED
binary logging. This can be changed by setting
create_temporary_table_binlog_formats to MIXED,STATEMENT.
- Using temporary tables that was not logged to the binary log will
cause any query using them for updating other tables to be logged in
ROW format. Before all queries was logged in ROW format if the user had
any temporary tables, even if they were not used by the query.
- Generated DROP TEMPORARY TABLE is now always using IF EXISTS and
has a "generated by server" comment in the binary log.
The consequences of the above is that manipulations of a lot of rows
through temporary tables will by default be be slower in mixed mode.
For example:
BEGIN;
CREATE TEMPORARY TABLE tmp AS SELECT a, b, c FROM
large_table1 JOIN large_table2 ON ...;
INSERT INTO other_table SELECT b, c FROM tmp WHERE a <100;
DROP TEMPORARY TABLE tmp;
COMMIT;
By default this will create a huge entry in the binary log, compared
to just a few hundred bytes in statement mode. However the change in
this commit will make usage of temporary tables more reliable and
predicable and is thus worth it. Using statement mode or
create_temporary_table_binlog_formats can be used to avoid this issue.
