When creating a recursive CTE, the column types are taken from the
non recursive part of the CTE (this is according to the SQL standard).
This patch adds code to abort the CTE if the calculated values in the
recursive part does not fit in the fields in the created temporary table.
The new code only affects recursive CTE, so it should not cause any notable
problems for old applications.
Other things:
- Fixed that we get correct row numbers for warnings generated with
WITH RECURSIVE
Reviewer: Alexander Barkov <bar@mariadb.com>
New Feature:
============
This patch adds a new system variable, @@slave_max_statement_time,
which limits the execution time of s slave’s events that implements
an equivalent to @@max_statement_time for slave applier.
Reviewed By:
============
Andrei Elkin <andrei.elkin@mariadb.com>
Part #2: Extend heuristic pruning to use multiple tables as the
"Model tables".
Before the patch, heuristic pruning uses only one "Model table":
The table which had the best cost AND record became the "Model table".
After that, if a table's cost and record were both worse than
those of the Model Table, the table would be pruned away.
This didn't work well when the first table (the optimizer sorts them
by record_count) had low record_count but relatively high cost: nothing
could be pruned afterwards.
The patch adds the two additional "Model tables": one with the least
cost and the other with the least record_count.
(In both cases, a table can be pruned away if BOTH its cost and
record_count are worse than those of a Model table)
The new pruning is active when the number of tables to consider for
the prefix is higher than @@optimizer_extra_pruning_depth.
One can see the new pruning in the Optimizer Trace as
- "pruned_by_heuristic":"min_record_count", or
- "pruned_by_heuristic":"min_read_time".
Old heuristic pruning shows as "pruned_by_heuristic":1.
MDEV-28073 Slow query performance in MariaDB when using many tables
The faster we can find a good query plan, the more options we have for
finding and pruning (ignoring) bad plans.
This patch adds sorting of plans to best_extension_by_limited_search().
The plans, from best_access_path() are sorted according to the numbers
of found rows. This allows us to faster find 'good tables' and we are
thus able to eliminate 'bad plans' faster.
One side effect of this patch is that if two tables have equal cost,
the table that which was used earlier in the query is preferred.
This allows users to improve plans by reordering eq_ref tables in the
order they would like them to be uses.
Result changes caused by the patch:
- Traces are different as now we print the cost for using tables before
we start considering them in the plan.
- Table order are changed for some plans. In most cases this is because
the plans are equal and tables are in this case sorted according to
their usage in the original query.
- A few plans was changed as the optimizer was able to find a better
plan (that was pruned by the original code).
Other things:
- Added a new statistic variable: "optimizer_join_prefixes_check_calls",
which counts number of calls to best_extension_by_limited_search().
This can be used to check the prune efficiency in greedy_search().
- Added variable "JOIN_TAB::embedded_dependent" to be able to handle
XX IN (SELECT..) in the greedy_optimizer. The idea is that we
should prune a table if any of the tables in embedded_dependent is
not yet read.
- When using many tables in a query, there will be some additional
memory usage as we need to pre-allocate table of
table_count*table_count*sizeof(POSITION) objects (POSITION is 312
bytes for now) to hold the pre-calculated best_access_path()
information. This memory usage is offset by the expected
performance improvement when using many tables in a query.
- Removed the code from an earlier patch to keep the table order in
join->best_ref in the original order. This is not needed anymore as we
are now sorting the tables for each best_extension_by_limited_search()
call.
Also fixes
MDEV-27782 Wrong columns when using table level `CHARACTER SET utf8mb4 COLLATE DEFAULT`
MDEV-28644 Unexpected error on ALTER TABLE t1 CONVERT TO CHARACTER SET utf8mb3, DEFAULT CHARACTER SET utf8mb4
MDEV-21810 MBR: Unexpected "Unsafe statement" warning for unsafe IODKU
MDEV-17614 fixes to replication unsafety for INSERT ON DUP KEY UPDATE
on two or more unique key table left a flaw. The fixes checked the
safety condition per each inserted record with the idea to catch a user-created
value to an autoincrement column and when that succeeds the autoincrement column
would become the source of unsafety too.
It was not expected that after a duplicate error the next record's
write_set may become different and the unsafe decision for that
specific record will be computed to screw the Query's binlogging
state and when @@binlog_format is MIXED nothing gets bin-logged.
This case has been already fixed in 10.5.2 by 91ab42a823 that
relocated/optimized THD::decide_logging_format_low() out of the record insert
loop. The safety decision is computed once and at the right time.
Pertinent parts of the commit are cherry-picked.
Also a spurious warning about unsafety is removed when MIXED
@@binlog_format; original MDEV-17614 test result corrected.
The original test of MDEV-17614 is extended and made more readable.
If UPDATE/DELETE does not change data it is skipped from
replication. We now force replication of such events when they trigger
partition auto-creation.
For ROLLBACK it is as simple as set OPTION_KEEP_LOG
flag. trans_cannot_safely_rollback() does the rest.
For UPDATE/DELETE .. LIMIT 0 we make additional binlog_query() calls
at the early points of return.
As a safety measure we also convert row format into statement if it is
needed. The condition is decided by
binlog_need_stmt_format(). Basically if there are some row events in
cache we don't need that: table open of row event will trigger
auto-creation anyway.
Multi-update/delete works via mysql_select(). There is no early points
of return, so binlogging is always checked by
send_eof()/abort_resultset(). But we must comply with the above
measure of converting into statement.
:: Syntax change ::
Keyword AUTO enables history partition auto-creation.
Examples:
CREATE TABLE t1 (x int) WITH SYSTEM VERSIONING
PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR AUTO;
CREATE TABLE t1 (x int) WITH SYSTEM VERSIONING
PARTITION BY SYSTEM_TIME INTERVAL 1 MONTH
STARTS '2021-01-01 00:00:00' AUTO PARTITIONS 12;
CREATE TABLE t1 (x int) WITH SYSTEM VERSIONING
PARTITION BY SYSTEM_TIME LIMIT 1000 AUTO;
Or with explicit partitions:
CREATE TABLE t1 (x int) WITH SYSTEM VERSIONING
PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR AUTO
(PARTITION p0 HISTORY, PARTITION pn CURRENT);
To disable or enable auto-creation one can use ALTER TABLE by adding
or removing AUTO from partitioning specification:
CREATE TABLE t1 (x int) WITH SYSTEM VERSIONING
PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR AUTO;
# Disables auto-creation:
ALTER TABLE t1 PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR;
# Enables auto-creation:
ALTER TABLE t1 PARTITION BY SYSTEM_TIME INTERVAL 1 HOUR AUTO;
If the rest of partitioning specification is identical to CREATE TABLE
no repartitioning will be done (for details see MDEV-27328).
:: Description ::
Before executing history-generating DML command (see the list of commands below)
add N history partitions, so that N would be sufficient for potentially
generated history. N > 1 may be required when history partitions are switched
by INTERVAL and current_timestamp is N times further than the interval
boundary of the last history partition.
If the last history partition equals or exceeds LIMIT records then new history
partition is created and selected as the working partition. According to
MDEV-28411 partitions cannot be switched (or created) while the command is
running. Thus LIMIT does not carry strict limitation and the history partition
size must be planned as LIMIT value plus average number of history one DML
command can generate.
Auto-creation is implemented by synchronous fast_alter_partition_table() call
from the thread of the executed DML command before the command itself is run
(by the fallback and retry mechanism similar to Discovery feature,
see Open_table_context).
The name for newly added partitions are generated like default partition names
with extension of MDEV-22155 (which avoids name clashes by extending assignment
counter to next free-enough gap).
These DML commands can trigger auto-creation:
DELETE (including multitable DELETE, excluding DELETE HISTORY)
UPDATE (including multitable UPDATE)
REPLACE (including REPLACE .. SELECT)
INSERT .. ON DUPLICATE KEY UPDATE (including INSERT .. SELECT .. ODKU)
LOAD DATA .. REPLACE
:: Bug fixes ::
MDEV-23642 Locking timeout caused by auto-creation affects original DML
The reasons for this are:
- Do not disrupt main business process (the history is auxiliary service);
- Consequences are non-fatal (history is not lost, but comes into wrong
partition; fixed by partitioning rebuild);
- There is more freedom for application to fail in this case or not: it may
read warning info and find corresponding error number.
- While non-failing command is easy to handle by an application and fail it,
the opposite is hard to handle: there is no automatic actions to fix
failed command and retry, DBA intervention is required and until then
application is non-functioning.
MDEV-23639 Auto-create does not work under LOCK TABLES or inside triggers
Don't do tdc_remove_table() for OT_ADD_HISTORY_PARTITION because it is
not possible in locked tables mode.
LTM_LOCK_TABLES mode (and LTM_PRELOCKED_UNDER_LOCK_TABLES) works out
of the box as fast_alter_partition_table() can reopen tables via
locked_tables_list.
In LTM_PRELOCKED we reopen and relock table manually.
:: More fixes ::
* some_table_marked_for_reopen flag fix
some_table_marked_for_reopen affets only reopen of
m_locked_tables. I.e. Locked_tables_list::reopen_tables() reopens only
tables from m_locked_tables.
* Unused can_recover_from_failed_open() condition
Is recover_from_failed_open() can be really used after
open_and_process_routine()?
:: Reviewed by ::
Sergei Golubchik <serg@mariadb.org>
rename OPTION_KEEP_LOG -> OPTION_BINLOG_THIS_TRX.
Meaning: transaction cache will be written to binlog even on rollback.
convert log_current_statement to OPTION_BINLOG_THIS_STMT.
Meaning: the statement will be written to binlog (or trx binlog cache)
even if it normally wouldn't be.
setting OPTION_BINLOG_THIS_STMT must always set OPTION_BINLOG_THIS_TRX,
otherwise the statement won't be logged if the transaction is rolled back.
Use OPTION_BINLOG_THIS to set both.
Problem:
========
If a primary is shutdown during an active semi-sync connection
during the period when the primary is awaiting an ACK, the primary
hard kills the active communication thread and does not ensure the
transaction was received by a replica. This can lead to an
inconsistent replication state.
Solution:
========
During shutdown, the primary should wait for an ACK or timeout
before hard killing a thread which is awaiting a communication. We
extend the `SHUTDOWN WAIT FOR SLAVES` logic to identify and ignore
any threads waiting for a semi-sync ACK in phase 1. Then, before
stopping the ack receiver thread, the shutdown is delayed until all
waiting semi-sync connections receive an ACK or time out. The
connections are then killed in phase 2.
Notes:
1) There remains an unresolved corner case that affects this
patch. MDEV-28141: Slave crashes with Packets out of order when
connecting to a shutting down master. Specifically, If a slave is
connecting to a master which is actively shutting down, the slave
can crash with a "Packets out of order" assertion error. To get
around this issue in the MTR tests, the primary will wait a small
amount of time before phase 1 killing threads to let the replicas
safely stop (if applicable).
2) This patch also fixes MDEV-28114: Semi-sync Master ACK Receiver
Thread Can Error on COM_QUIT
Reviewed By
============
Andrei Elkin <andrei.elkin@mariadb.com>
Analysis: There are 2 server variables- "old_mode" and "old". "old" is no
longer needed as "old_mode" has replaced it (however still used in some places
in the code). "old_mode" and "old" has same purpose- emulate behavior from
previous MariaDB versions. So they can be merged to avoid confusion.
Fix: Deprecate "old" variable and create another mode for @@old_mode to mimic
behavior of previous "old" variable. Create specific modes for specifix task
that --old sql variable was doing earlier and use the new modes instead.
the bug was that in_vector array in Item_func_in was allocated in the
statement arena, not in the table->expr_arena.
revert part of the 5acd391e8b. Instead, change the arena correctly
in fix_all_session_vcol_exprs().
Remove TABLE_ARENA, that was introduced in 5acd391e8b to force
item tree changes to be rolled back (because they were allocated in the
wrong arena and didn't persist. now they do)
Problem: In regular replication, when master binlogged using statement format
slave might not have written an event to its binary log when the Query
event aimed at a temporary table.
Specifically this was observed with LOAD DATA INFILE.
This effect was possible because unlike master slave holds temporary
tables in its pool and the master side check of existence of a
temporary table at the format bin-logging decision did not apply.
Solution: replace THD::has_thd_temporary_tables() with
THD::has_temporary_tables which allows to identify temporary table
presence on either side.
--
Reviewed by Andrei Elkin.
Using parallel slave applying can cause deadlock between between DDL and
other events. GTID with lower seqno can be blocked in galera when node
entered TOI mode, but DDL GTID which has higher node can be blocked
before previous GTIDs are applied locally.
Fix is to check prior commits before entering TOI.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>
Handling BF abort for prepared statement execution so that EXECUTE processing will continue
until parameter setup is complete, before BF abort bails out the statement execution.
THD class has new boolean member: wsrep_delayed_BF_abort, which is set if BF abort is observed
in do_command() right after reading client's packet, and if the client has sent PS execute command.
In such case, the deadlock error is not returned immediately back to client, but the PS execution
will be started. However, the PS execution loop, will now check if wsrep_delayed_BF_abort is set, and
stop the PS execution after the type information has been assigned for the PS.
With this, the PS protocol type information, which is present in the first PS EXECUTE command, is not lost
even if the first PS EXECUTE command was marked to abort.
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>
extra2_read_len resolved by keeping the implementation
in sql/table.cc by exposed it for use by ha_partition.cc
Remove identical implementation in unireg.h
(ref: bfed2c7d57)
