Atomic CREATE OR REPLACE allows to keep an old table intact if the
command fails or during the crash. That is done by renaming the
original table to temporary name, as a backup and restoring it if the
CREATE fails. 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 rename of ORIG to TMP table (Rename TMP to original).
2. Rename orignal to TMP.
3. (C) Log CREATE_TABLE_ACTION of ORIG (drops ORIG);
4. Do everything with ORIG (like insert data)
5. (D) Log drop of TMP
6. Write query to binlog (this marks (C) to be closed in
case of failure)
7. Execute drop of TMP through (D)
8. Close (C) and (D)
If there is a failure before 6) we revert the changes in (C)
Chain (D) is only executed if 6) succeded (C is closed on
crash recovery).
Foreign key errors will be found at the 1) stage.
Additional notes
- CREATE TABLE without REPLACE and temporary tables is not affected
by this commit.
set @@drop_before_create_or_replace=1 can be used to
get old behaviour where existing tables are dropped
in CREATE OR REPLACE.
- CREATE TABLE is reverted if binlogging the query fails.
- Engines having HTON_EXPENSIVE_RENAME flag set are not affected by
this commit. Conflicting tables marked with this flag will be
deleted with CREATE OR REPLACE.
- Replication execution is not affected by this commit.
- Replication will first drop the conflicting table and then
creating the new one.
- 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 new
table is created or TMP is renamed back to ORIG
- 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
backup ddl log changes
- In case of a successfull CREATE OR REPLACE we only log
the CREATE event, not the DROP TABLE event of the old table.
ddl_log.cc changes
ddl_log_execute_action() now properly return error conditions.
ddl_log_disable_entry() added to allow one to disable one entry.
The entry on disk is still reserved until ddl_log_complete() is
executed.
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 defined in "MDEV-22166
ddl_log_write_execute_entry() extension".
Atomic info parameters 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.
Aria changes:
- Fixed issue in Aria engine with CREATE + locked tables
that data was not properly commited in some cases in
case of crashes.
InnoDB related changes (by Marko Mäkelä):
- table_name_t::is_create_or_replace(): A new predicate to check for
CREATE OR REPLACE TABLE will rename an old table to
and eventually drop after creating the replacement.
- dict_table_t::parse_name(): Do acquire MDL on #sql-create- names
for partitioned tables.
- dict_table_rename_in_cache(): On CREATE OR REPLACE TABLE ... SELECT,
forget the original dict_table_t::mdl_name so that purge will
acquire MDL on the #sql-create- name instead. In this way, the
MDL_EXCLUSIVE that the CREATE OR REPLACE TABLE holds on the
user-visible name will not unnecessarily block any purge of old history
until the very end when the #sql-create- table will be dropped.
- ha_innobase::delete_table(): Do not check FOREIGN KEY consistency
when dropping an #sql-create- table.
- row_rename_table_for_mysql(): Update SYS_FOREIGN.ID also
when renaming to #sql-create- in order to avoid any
duplicate key error when CREATE OR REPLACE TABLE is
creating some FOREIGN KEY constraints by names
that existed in the old table.
Other changes:
- Removed some auto variables in log.cc for better code readability.
- Fixed old bug that CREATE ... SELECT would not be able to auto repair
a table that is part of the SELECT.
- Marked MyISAM that it does not support ROLLBACK (not required but
done for better consistency with other engines).
- maria_create_trn_for_mysql() does not register a new transaction
handler for commits. This was needed to ensure create or replace
will not end with an active transaction.
- We do not get anymore warnings about "Engine not supporting atomic
create" when doing a legal CREATE OR REPLACE on a table with
foreign key constraints.
- Updated VIDEX engine flags to disable CREATE SEQUENCE.
- Removed mysql_mutex_unlock(&LOCK_gdl) / mysql_mutex_lock(&LOCK_gdl)
around calls to binlog as these are unsafe. The binlog code uses
global variables that needs protection from other caller.
- EITS data is preserved if create or replace fails if
drop_before_create_or_replace=OFF. If ON, then create or replace
will drop EITS before the drop of the original table (as before).
- Using CREATE OR REPLACE on a encrypted table that the user cannot
decrypt will fail instead of replacing the encrypted table.
The encrypted table will unchanged.
Known issues:
- One cannot use create or replace on an InnoDB tables that has foreign
key references point to it
- CREATE OR REPLACE TEMPORARY table is not full atomic. Any conflicting
table will always be dropped before creating a new one. (Old behaviour).
Bug fixes related to this MDEV:
MDEV-36435 Assertion failure in finalize_locked_tables()
MDEV-36439 Assertion `thd_arg->lex->sql_command != SQLCOM_CREATE_SEQUENCE...
MDEV-36498 Failed CoR in non-atomic mode no longer generates DROP in RBR...
MDEV-36508 Temporary files #sql-create-....frm occasionally stay after
crash recovery
MDEV-38479 Crash in CREATE OR REPLACE SEQUENCE when new sequence cannot
be created
MDEV-36497 Assertion failure after atomic CoR with Aria under lock in
transactional context
MDEV-36501 EITS data is lost after failed attempt to CREATE OR REPLACE
table
MDEV-36493 Atomic CREATE OR REPLACE ... SELECT blocks InnoDB purge
MDEV-39367 MSAN/valgrind errors in temp_file_size_cb_func,
main.tmp_space_usage fails
MDEV-39446 Atomic CREATE OR REPLACE fails if a table cannot be decrypted
MDEV-40776 Atomic CREATE OR REPLACE silently breaks the foreign key
MDEV-40765 Assertion `"unexpected references" == 0' failed upon failing
CREATE OR REPLACE
MDEV-40994 Atomic CoR: Transaction not registered for MariaDB 2PC, but
transaction is active
Reverted commits:
- MDEV-36685 "CREATE-SELECT may lose in binlog side-effects of
stored-routine" as it did not take into account that it safe to
clear binlogs if the created table is non transactional and there
are no other non transactional tables used.
This was done because it caused extra logging when it is not
needed (not using any non transactional tables) and it also did
not solve side effects when using statement based loggging.
1.
Only allow #mysql50# prefix on table names that
can not be decoded from a file name to a table name.
It is an error to put this prefix on a name that can be accessed
as a valid table name without a prefix. Use `t1` not `#mysql50#t1`,
use `a-b` not `#mysql50#a@002db`.
2.
Don't allow creation of new tables with the #mysql50# prefix.
Except when in SQLCOM_ALTER_DB_UPGRADE - main.upgrade test runs
ALTER DATABASE `#mysql50#mysqltest-1` UPGRADE DATA DIRECTORY NAME;
This command moves tables from the old db name to the new db name,
and some of these tables also have old #mysql50# names.
3.
Also don't allow to create such databases, views, partitions,
subpartitions, sequences, triggers.
The method Type_handler::Column_definition_fix_attributes() was an
addition for Type_handler::Column_definition_set_attributes().
The code in virtual implementations of Column_definition_fix_attributes()
has now been joined to corresponding virtual implementations of
Column_definition_set_attributes().
After this change everything is done in Column_definition_set_attributes().
This makes the code clearer. Previous implementation was rather confusing.
For example, for temporal data types:
(1) After Column_definition_set_attributes():
- Column_definition::length meant the fractional precision
- Column_definition::decimals was set to 0
(2) After Column_definition_fix_attributes():
- Column_definition::length means the full character length
- Column_definition::decimals means the fractional precision
Now everything gets set to (2) right in Column_definition_set_attributes().
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.
MDEV-33658 part 1’s refactoring ecaedbe299
introduced a new function init_key_info which (in part) aims to
calculate the total key length; however, it doesn’t account for the
key already having been initialized (as happens when called via
ALTER TABLE .. CONVERT PARTITION .. TO TABLE). This leads to crashes
when this key is later iterated over, because the iterator will try
to iterate over additional key parts which don’t exist because the
length reports as longer than the actual memory owned. The crash
reported by MDEV-36906 highlights this in function key_copy.
To explain how the keys already have been initialized, init_key_info
is called multiple times. That is, init_key_info is called from
mysql_prepare_create_table, which prepares a table and its key
structures for table creation, which is in turn called by
mysql_write_frm when using flags MFRM_WRITE_SHADOW and
MFRM_WRITE_CONVERTED_TO. The
ALTER TABLE .. CONVERT PARTITION .. TO TABLE use case (see function
fast_alter_partition_table), calls mysql_write_frm multiple times with
both of these flags set (first with MFRM_WRITE_CONVERTED_TO and then
with MFRM_WRITE_SHADOW).
Raising it up a level, mysql_prepare_create_table doesn't need to be
called again after it has already been invoked when just writing frms.
Init_key_info is the only place in that function which leads to side
effects, but the rest is redundant and can be skipped on the second
call (i.e. when writing the shadow).
The patch fixes this by skipping the call to mysql_prepare_create_table
in mysql_write_frm in the MFRM_WRITE_SHADOW block when it has already
been called previously. To track whether or not it has been previously
called, we add a new flag for the mysql_write_frm function,
MFRM_ALTER_INFO_PREPARED, which is hard-coded into the function call on
the later invocation.
Test case based on work by Elena Stepanova <elenst@mariadb.com>
Reviewed By:
============
Sergei Golubchik <serg@mariadb.org>
Nikita Malyavin <nikita.malyavin@mariadb.com>
There is a need in MDEV-25292 to have both C_ALTER_TABLE and
select_field_count in one call. Semantically creation mode and field
count are two different things. Making creation mode negative
constants and field count positive variable into one parameter seems
to be a lazy hack for not making the second parameter.
select_count does not make sense without alter_info->create_list, so
the natural way is to hold it in Alter_info too. select_count is now
stored in member select_field_count.
Merged and updated by: Monty
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.
when adding a column or index that uses plugin-defined
sysvar-based options with ALTER TABLE ... ADD, the server
was using the default value of the sysvar, not the current one.
CREATE TABLE was correctly using the current sysvar value.
Fix it so that new columns/indexes added in ALTER TABLE ... ADD
would use a current sysvar value. Existing columns/indexes
in ALTER TABLE would keep using the default sysvar value
(unless they had an explicit value in frm).
When adding a column or index that uses plugin-defined
sysvar-based options with CREATE ... LIKE the server
was using the current value of the sysvar, not the default one.
Because parse_option_list() function was used both in create
and open and it tried to guess when it's create (need to use
current sysvar value and add a new name=value pair to the list)
or open (need to use default, without extending the list).
Let's move the list extending functionality into a separate
function and call it explicitly when needed. Operations that
add new objects (CREATE, ALTER ... ADD) will extend the list,
other operations (ALTER, CREATE ... LIKE, open) will not.
This task is to ensure we have a clear definition and rules of how to
repair or optimize a table.
The rules are:
- REPAIR should be used with tables that are crashed and are
unreadable (hardware issues with not readable blocks, blocks with
'unexpected data' etc)
- OPTIMIZE table should be used to optimize the storage layout for the
table (recover space for delete rows and optimize the index
structure.
- ALTER TABLE table_name FORCE should be used to rebuild the .frm file
(the table definition) and the table (with the original table row
format). If the table is from and older MariaDB/MySQL release with a
different storage format, it will convert the data to the new
format. ALTER TABLE ... FORCE is used as part of mariadb-upgrade
Here follows some more background:
The 3 ways to repair a table are:
1) ALTER TABLE table_name FORCE" (not other options).
As an alias we allow: "ALTER TABLE table_name ENGINE=original_engine"
2) "REPAIR TABLE" (without FORCE)
3) "OPTIMIZE TABLE"
All of the above commands will optimize row space usage (which means that
space will be needed to hold a temporary copy of the table) and
re-generate all indexes. They will also try to replicate the original
table definition as exact as possible.
For ALTER TABLE and "REPAIR TABLE without FORCE", the following will hold:
If the table is from an older MariaDB version and data conversion is
needed (for example for old type HASH columns, MySQL JSON type or new
TIMESTAMP format) "ALTER TABLE table_name FORCE, algorithm=COPY" will be
used.
The differences between the algorithms are
1) Will use the fastest algorithm the engine supports to do a full repair
of the table (except if data conversions are is needed).
2) Will use the storage engine internal REPAIR facility (MyISAM, Aria).
If the engine does not support REPAIR then
"ALTER TABLE FORCE, ALGORITHM=COPY" will be used.
If there was data incompatibilities (which means that FORCE was used)
then there will be a warning after REPAIR that ALTER TABLE FORCE is
still needed.
The reason for this is that REPAIR may be able to go around data
errors (wrong incompatible data, crashed or unreadable sectors) that
ALTER TABLE cannot do.
3) Will use the storage engine internal OPTIMIZE. If engine does not
support optimize, then "ALTER TABLE FORCE" is used.
The above will ensure that ALTER TABLE FORCE is able to
correct almost any errors in the row or index data. In case of
corrupted blocks then REPAIR possible followed by ALTER TABLE is needed.
This is important as mariadb-upgrade executes ALTER TABLE table_name
FORCE for any table that must be re-created.
Bugs fixed with InnoDB tables when using ALTER TABLE FORCE:
- No error for INNODB_DEFAULT_ROW_FORMAT=COMPACT even if row length
would be too wide. (Independent of innodb_strict_mode).
- Tables using symlinks will be symlinked after any of the above commands
(Independent of the setting of --symbolic-links)
If one specifies an algorithm together with ALTER TABLE FORCE, things
will work as before (except if data conversion is required as then
the COPY algorithm is enforced).
ALTER TABLE .. OPTIMIZE ALL PARTITIONS will work as before.
Other things:
- FORCE argument added to REPAIR to allow one to first run internal
repair to fix damaged blocks and then follow it with ALTER TABLE.
- REPAIR will not update frm_version if ha_check_for_upgrade() finds
that table is still incompatible with current version. In this case the
REPAIR will end with an error.
- REPAIR for storage engines that does not have native repair, like InnoDB,
is now using ALTER TABLE FORCE.
- REPAIR csv-table USE_FRM now works.
- It did not work before as CSV tables had extension list in wrong
order.
- Default error messages length for %M increased from 128 to 256 to not
cut information from REPAIR.
- Documented HA_ADMIN_XX variables related to repair.
- Added HA_ADMIN_NEEDS_DATA_CONVERSION to signal that we have to
do data conversions when converting the table (and thus ALTER TABLE
copy algorithm is needed).
- Fixed typo in error message (caused test changes).
This patch also fixes:
MDEV-33050 Build-in schemas like oracle_schema are accent insensitive
MDEV-33084 LASTVAL(t1) and LASTVAL(T1) do not work well with lower-case-table-names=0
MDEV-33085 Tables T1 and t1 do not work well with ENGINE=CSV and lower-case-table-names=0
MDEV-33086 SHOW OPEN TABLES IN DB1 -- is case insensitive with lower-case-table-names=0
MDEV-33088 Cannot create triggers in the database `MYSQL`
MDEV-33103 LOCK TABLE t1 AS t2 -- alias is not case sensitive with lower-case-table-names=0
MDEV-33109 DROP DATABASE MYSQL -- does not drop SP with lower-case-table-names=0
MDEV-33110 HANDLER commands are case insensitive with lower-case-table-names=0
MDEV-33119 User is case insensitive in INFORMATION_SCHEMA.VIEWS
MDEV-33120 System log table names are case insensitive with lower-cast-table-names=0
- Removing the virtual function strnncoll() from MY_COLLATION_HANDLER
- Adding a wrapper function CHARSET_INFO::streq(), to compare
two strings for equality. For now it calls strnncoll() internally.
In the future it will turn into a virtual function.
- Adding new accent sensitive case insensitive collations:
- utf8mb4_general1400_as_ci
- utf8mb3_general1400_as_ci
They implement accent sensitive case insensitive comparison.
The weight of a character is equal to the code point of its
upper case variant. These collations use Unicode-14.0.0 casefolding data.
The result of
my_charset_utf8mb3_general1400_as_ci.strcoll()
is very close to the former
my_charset_utf8mb3_general_ci.strcasecmp()
There is only a difference in a couple dozen rare characters, because:
- the switch from "tolower" to "toupper" comparison, to make
utf8mb3_general1400_as_ci closer to utf8mb3_general_ci
- the switch from Unicode-3.0.0 to Unicode-14.0.0
This difference should be tolarable. See the list of affected
characters in the MDEV description.
Note, utf8mb4_general1400_as_ci correctly handles non-BMP characters!
Unlike utf8mb4_general_ci, it does not treat all BMP characters
as equal.
- Adding classes representing names of the file based database objects:
Lex_ident_db
Lex_ident_table
Lex_ident_trigger
Their comparison collation depends on the underlying
file system case sensitivity and on --lower-case-table-names
and can be either my_charset_bin or my_charset_utf8mb3_general1400_as_ci.
- Adding classes representing names of other database objects,
whose names have case insensitive comparison style,
using my_charset_utf8mb3_general1400_as_ci:
Lex_ident_column
Lex_ident_sys_var
Lex_ident_user_var
Lex_ident_sp_var
Lex_ident_ps
Lex_ident_i_s_table
Lex_ident_window
Lex_ident_func
Lex_ident_partition
Lex_ident_with_element
Lex_ident_rpl_filter
Lex_ident_master_info
Lex_ident_host
Lex_ident_locale
Lex_ident_plugin
Lex_ident_engine
Lex_ident_server
Lex_ident_savepoint
Lex_ident_charset
engine_option_value::Name
- All the mentioned Lex_ident_xxx classes implement a method streq():
if (ident1.streq(ident2))
do_equal();
This method works as a wrapper for CHARSET_INFO::streq().
- Changing a lot of "LEX_CSTRING name" to "Lex_ident_xxx name"
in class members and in function/method parameters.
- Replacing all calls like
system_charset_info->coll->strcasecmp(ident1, ident2)
to
ident1.streq(ident2)
- Taking advantage of the c++11 user defined literal operator
for LEX_CSTRING (see m_strings.h) and Lex_ident_xxx (see lex_ident.h)
data types. Use example:
const Lex_ident_column primary_key_name= "PRIMARY"_Lex_ident_column;
is now a shorter version of:
const Lex_ident_column primary_key_name=
Lex_ident_column({STRING_WITH_LEN("PRIMARY")});
Problem is that Galera starts TOI (total order isolation) i.e.
it sends query to all nodes. Later it is discovered that
used engine or other feature is not supported by Galera.
Because TOI is executed parallelly in all nodes appliers
could execute given TOI and ignore the error and
start inconsistency voting causing node to leave from
cluster or we might have a crash as reported.
For example SEQUENCE engine does not support GEOMETRY data
type causing either inconsistency between nodes (because
some errors are ignored on applier) or crash.
Fixed my adding new function wsrep_check_support to check
can Galera support provided CREATE TABLE/SEQUENCE before TOI is
started and if not clear error message is provided to
the user.
Currently, not supported cases:
* CREATE TABLE ... AS SELECT when streaming replication is used
* CREATE TABLE ... WITH SYSTEM VERSIONING AS SELECT
* CREATE TABLE ... ENGINE=SEQUENCE
* CREATE SEQUENCE ... ENGINE!=InnoDB
* ALTER TABLE t ... ENGINE!=InnoDB where table t is SEQUENCE
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>
Problem for Galera is the fact that sequences are not really
transactional. Sequence operation is committed immediately
in sql_sequence.cd and later Galera could find out that
we have changes but actual statement is not there anymore.
Therefore, we must make some restrictions what kind
of sequences Galera can support.
(1) Galera cluster supports only sequences implemented
by InnoDB storage engine. This is because Galera replication
supports currently only InnoDB.
(2) We do not allow LOCK TABLE on sequence object and
we do not allow sequence creation under LOCK TABLE, instead
lock is released and we issue warning.
(3) We allow sequences with NOCACHE definition or with
INCREMEMENT BY 0 CACHE=n definition. This makes sure that
sequence values are unique accross Galera cluster.
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>
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
This commit implements two phase binloggable ALTER.
When a new
@@session.binlog_alter_two_phase = YES
ALTER query gets logged in two parts, the START ALTER and the COMMIT
or ROLLBACK ALTER. START Alter is written in binlog as soon as
necessary locks have been acquired for the table. The timing is
such that any concurrent DML:s that update the same table are either
committed, thus logged into binary log having done work on the old
version of the table, or will be queued for execution on its new
version.
The "COMPLETE" COMMIT or ROLLBACK ALTER are written at the very point
of a normal "single-piece" ALTER that is after the most of
the query work is done. When its result is positive COMMIT ALTER is
written, otherwise ROLLBACK ALTER is written with specific error
happened after START ALTER phase.
Replication of two-phase binloggable ALTER is
cross-version safe. Specifically the OLD slave merely does not
recognized the start alter part, still being able to process and
memorize its gtid.
Two phase logged ALTER is read from binlog by mysqlbinlog to produce
BINLOG 'string', where 'string' contains base64 encoded
Query_log_event containing either the start part of ALTER, or a
completion part. The Query details can be displayed with `-v` flag,
similarly to ROW format events. Notice, mysqlbinlog output containing
parts of two-phase binloggable ALTER is processable correctly only by
binlog_alter_two_phase server.
@@log_warnings > 2 can reveal details of binlogging and slave side
processing of the ALTER parts.
The current commit also carries fixes to the following list of
reported bugs:
MDEV-27511, MDEV-27471, MDEV-27349, MDEV-27628, MDEV-27528.
Thanks to all people involved into early discussion of the feature
including Kristian Nielsen, those who helped to design, implement and
test: Sergei Golubchik, Andrei Elkin who took the burden of the
implemenation completion, Sujatha Sivakumar, Brandon
Nesterenko, Alice Sherepa, Ramesh Sivaraman, Jan Lindstrom.
Syntax for CONVERT keyword
ALTER TABLE tbl_name
[alter_option [, alter_option] ...] |
[partition_options]
partition_option: {
...
| CONVERT PARTITION partition_name TO TABLE tbl_name
}
Examples:
ALTER TABLE t1 CONVERT PARTITION p2 TO TABLE tp2;
New ALTER_PARTITION_CONVERT_OUT command for
fast_alter_partition_table() is done in alter_partition_convert_out()
function which basically does ha_rename_table().
Partition to extract is marked with the same flag as dropped
partition: PART_TO_BE_DROPPED. Note that we cannot have multiple
partitioning commands in one ALTER.
For DDL logging basically the principle is the same as for other
fast_alter_partition_table() commands. The only difference is that it
integrates late Atomic DDL functions and introduces additional phase
of WFRM_BACKUP_ORIGINAL. That is required for binlog consistency
because otherwise we could not revert back after WFRM_INSTALL_SHADOW
is done. And before DDL log is complete if we crash or fail the
altered table will be already new but binlog will miss that ALTER
command. Note that this is different from all other atomic DDL in that
it rolls back until the ddl_log_complete() is done even if everything
was done fully before the crash.
Test cases added to:
parts.alter_table \
parts.partition_debug \
versioning.partition \
atomic.alter_partition
Withing this task the following changes were made:
- Added sending of metadata info in prepare phase for the admin related
command (check table, checksum table, repair, optimize, analyze).
- Refactored implmentation of HELP command to support its execution in
PS mode
- Added support for execution of LOAD INTO and XA- related statements
in PS mode
- Modified mysqltest.cc to run statements in PS mode unconditionally
in case the option --ps-protocol is set. Formerly, only those statements
were executed using PS protocol that matched the hard-coded regular expression
- Fixed the following issues:
The statement
explain select (select 2)
executed in regular and PS mode produces different results:
MariaDB [test]> prepare stmt from "explain select (select 2)";
Query OK, 0 rows affected (0,000 sec)
Statement prepared
MariaDB [test]> execute stmt;
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
| 1 | PRIMARY | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
| 2 | SUBQUERY | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
2 rows in set (0,000 sec)
MariaDB [test]> explain select (select 2);
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
| 1 | SIMPLE | NULL | NULL | NULL | NULL | NULL | NULL | NULL | No tables used |
+------+-------------+-------+------+---------------+------+---------+------+------+----------------+
1 row in set, 1 warning (0,000 sec)
In case the statement
CREATE TABLE t1 SELECT * FROM (SELECT 1 AS a, (SELECT a+0)) a
is run in PS mode it fails with the error
ERROR 1054 (42S22): Unknown column 'a' in 'field list'.
- Uniform handling of read-only variables both in case the SET var=val
statement is executed as regular or prepared statememt.
- Fixed assertion firing on handling LOAD DATA statement for temporary tables
- Relaxed assert condition in the function lex_end_stage1() by adding
the commands SQLCOM_ALTER_EVENT, SQLCOM_CREATE_PACKAGE,
SQLCOM_CREATE_PACKAGE_BODY to a list of supported command
- Removed raising of the error ER_UNSUPPORTED_PS in the function
check_prepared_statement() for the ALTER VIEW command
- Added initialization of the data memember st_select_lex_unit::last_procedure
(assign NULL value) in the constructor
Without this change the test case main.ctype_utf8 fails with the following
report in case it is run with the optoin --ps-protocol.
mysqltest: At line 2278: query 'VALUES (_latin1 0xDF) UNION VALUES(_utf8'a' COLLATE utf8_bin)' failed: 2013: Lost connection
- The following bug reports were fixed:
MDEV-24460: Multiple rows result set returned from stored
routine over prepared statement binary protocol is
handled incorrectly
CONC-519: mariadb client library doesn't handle server_status and
warnign_count fields received in the packet
COM_STMT_EXECUTE_RESPONSE.
Reasons for these bug reports have the same nature and caused by
missing loop iteration on results sent by server in response to
COM_STMT_EXECUTE packet.
Enclosing of statements for processing of COM_STMT_EXECUTE response
in the construct like
do
{
...
} while (!mysql_stmt_next_result());
fixes the above mentioned bug reports.
There are a few different cases to consider
Logging of CREATE TABLE and CREATE TABLE ... LIKE
- If REPLACE is used and there was an existing table, DDL log the drop of
the table.
- If discovery of table is to be done
- DDL LOG create table
else
- DDL log create table (with engine type)
- create the table
- If table was created
- Log entry to binary log with xid
- Mark DDL log completed
Crash recovery:
- If query was in binary log do nothing and exit
- If discoverted table
- Delete the .frm file
-else
- Drop created table and frm file
- If table was dropped, write a DROP TABLE statement in binary log
CREATE TABLE ... SELECT required a little more work as when one is using
statement logging the query is written to the binary log before commit is
done.
This was fixed by adding a DROP TABLE to the binary log during crash
recovery if the ddl log entry was not closed. In this case the binary log
will contain:
CREATE TABLE xxx ... SELECT ....
DROP TABLE xxx;
Other things:
- Added debug_crash_here() functionality to Aria to be able to test
crash in create table between the creation of the .MAI and the .MAD files.
Description of how DROP DATABASE works after this patch
- Collect list of tables
- DDL log tables as they are dropped
- DDL log drop database
- Delete db.opt
- Delete data directory
- Log either DROP TABLE or DROP DATABASE to binary log
- De active ddl log entry
This is in line of how things where before (minus ddl logging) except that
we delete db.opt file last to not loose it if DROP DATABASE fails.
On recovery we have to ensure that all dropped tables are logged in
binary log and that they are properly dropped (as with atomic drop
table).
No new tables be dropped as part of recovery.
Recovery of active drop database ddl log entry:
- If drop database was logged to ddl log but was not found in the binary
log:
- drop the db.opt file and database directory.
- Log DROP DATABASE to binary log
- If drop database was not logged to ddl log
- Update binary log with DROP TABLE of the dropped tables. If table list
is longer than max_allowed_packet, then the query will be split into
multiple DROP TABLE/VIEW queries.
Other things:
- Added DDL_LOG_STATE and 'current database' as arguments to
mysql_rm_table_no_locks(). This was needed to be able to combine
ddl logging of DROP DATABASE and DROP TABLE and make the generated
DROP TABLE statements shorter.
- To make the DROP TABLE statement created by ddl log shorter, I changed
the binlogged query to use current directory and omit the directory
part for all tables in the current directory.
- Merged some DROP TABLE and DROP VIEW code in ddl logger. This was done
to be able get separate DROP VIEW and DROP TABLE statements in the binary
log.
- Added a 'recovery_state' variable to remember the state of dropped
tables and views.
- Moved out code that drops database objects (stored procedures) from
mysql_rm_db_internal() to drop_database_objects() for better code reuse.
- Made mysql_rm_db_internal() global so that could be used by the ddl
recovery code.
