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).
Remove alter_algorithm but keep the variable as no-op (with a warning).
The reasons for removing alter_algorithm are:
- alter_algorithm was introduced as a replacement for the
old_alter_table that was used to force the usage of the original
alter table algorithm (copy) in the cases where the new alter
algorithm did not work. The new option was added as a way to force
the usage of a specific algorithm when it should instead have made
it possible to disable algorithms that would not work for some
reason.
- alter_algorithm introduced some cases where ALTER TABLE would not
work without specifying the ALGORITHM=XXX option together with
ALTER TABLE.
- Having different values of alter_algorithm on master and slave could
cause slave to stop unexpectedly.
- ALTER TABLE FORCE, as used by mariadb-upgrade, would not always work
if alter_algorithm was set for the server.
- As part of the MDEV-33449 "improving repair of tables" it become
clear that alter- algorithm made it harder to provide a better and
more consistent ALTER TABLE FORCE and REPAIR TABLE and it would be
better to remove it.
on disable_indexes(HA_KEY_SWITCH_NONUNIQ_SAVE) the engine does
not know that the long unique is logically unique, because on the
engine level it is not. And the engine disables it,
Change the disable_indexes/enable_indexes API. Instead of the enum
mode, send a key_map of indexes that should be enabled. This way the
server will decide what is unique, not the engine.
Assertion "from->s->online_alter_binlog == NULL" fails in
copy_data_between_tables, signalizing that a table share is being reused
(in another alter) after a lock upgrade to EXCLUSIVE fails.
Commit 3059f27 relaxed the lock to be upgraded to MDL_SHARED_NO_WRITE, leaving
it to happen later by a common path wait_while_table_is_used() call.
However the error handling there is not enough for online alter case, where we
require (for now) the table to be flushed, in order to clean up the memory
properly.
* Add another lock upgrade (to MDL_EXCLUSIVE) after the second replication stage
in copy_data_between_tables.
The error from this upgrade will be handled by the branch presented further in
the function.
MDEV-33450 Assertion fails in main.alter_table_online_debug
`TABLE_SHARE` that is being online-altered has a shared `s->online_alter_binlog`
member that all concurrent DMLs are writing to. Online alter thread deletes it
under the MDL_EXCLUSIVE. If upgrading the lock to MDL_EXCLUSIVE fails, table as
marked as `flushed` and it's freed automatically when its usage drops to zero.
In commit 3059f27 the lock upgrade was relaxed to MDL_SHARED_NO_WRITE to allow
concurrent SELECT threads during the final `online_alter_read_from_binlog()`
pass. An attempt to upgrade the lock to MDL_EXCLUSIVE was still happening, but
much later — after the code that marked the table `flushed`.
That is, if the upgrade failed, the table was left with a stale
`s->online_alter_binlog` triggering an assert in a future online alter.
To fix this, upgrade the lock to MDL_EXCLUSIVE earlier, after the final
`online_alter_read_from_binlog()`.
Fixing the problem that an operation involving a mix of
two or more GEOMETRY operands did not preserve their SRIDs.
Now SRIDs are preserved by hybrid functions, subqueries, TVCs, UNIONs, VIEWs.
Incompatible change:
An attempt to mix two different SRIDs now raises an error.
Details:
- Adding a new class Type_extra_attributes. It's a generic
container which can store very specific data type attributes.
For now it can store one uint32 and one const pointer attribute
(for GEOMETRY's SRID and for ENUM/SET TYPELIB respectively).
In the future it can grow as needed.
Type_extra_attributes will also be reused soon to store "const Type_zone*"
pointers for the TIMESTAMP's "WITH TIME ZONE 'tz'" attribute
(a timestamp data type with a fixed time zone independent from @@time_zone).
The time zone attribute will be stored in exactly the same way like
a TYPELIB pointer is stored by ENUM/SET.
- Removing Column_definition_attributes members "interval" and "srid".
Deriving Column_definition_attributes from the generic attribute container
Type_extra_attributes instead.
- Adding a new class Type_typelib_attributes, to store
the TYPELIB of the ENUM and SET data types. Deriving Field_enum from it.
Removing the member Field_enum::typelib.
- Adding a new class Type_geom_attributes, to store
the GEOMETRY related attributes. Deriving Field_geom from it.
Removing the member Field_geom::srid.
- Removing virtual methods:
Field::get_typelib()
Type_all_attributes::get_typelib() and
Type_all_attributes::set_typelib()
They were very specific to TYPELIB.
Adding more generic virtual methods instead:
* Field::type_extra_attributes() - to get extra attributes
* Type_all_attributes::type_extra_attributes() - to get extra attributes
* Type_all_attributes::type_extra_attributes_addr() - to set extra attributes
- Removing Item_type_holder::enum_set_typelib. Deriving Item_type_holder
from the generic attribute container Type_extra_attributes instead.
This makes it possible for UNION to preserve SRID
(in addition to preserving TYPELIB).
- Deriving Item_hybrid_func from Type_extra_attributes.
This makes it possible for hybrid functions (e.g. CASE, COALESCE,
LEAST, GREATEST etc) to preserve SRID.
- Deriving Item_singlerow_subselect from Type_extra_attributes and
overriding methods:
* Item_cache::type_extra_attributes()
* subselect_single_select_engine::fix_length_and_dec()
* Item_singlerow_subselect::type_extra_attributes()
* Item_singlerow_subselect::type_extra_attributes_addr()
This is needed to preserve SRID in subqueries and TVCs
- Cleanup: fixing the data type of members
* Binlog_type_info::m_enum_typelib
* Binlog_type_info::m_set_typelib
from "TYPELIB *" to "const TYPELIB *"
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")});
The discovered memory leak was introduced by the commit
762bf7a03b
(MDEV-22602 Disable UPDATE CASCADE for SQL constraints)
The reason why a memory leaked on running the test main.constraints
is that a statement arena was used for allocation a memory
for storing a constraint name. A constraint name is an entity having
temporary nature by its design so runtime arena should be used for its
allocation.
Some fixes related to commit f838b2d799 and
Rows_log_event::do_apply_event() and Update_rows_log_event::do_exec_row()
for system-versioned tables were provided by Nikita Malyavin.
This was required by test versioning.rpl,trx_id,row.
In case there is a view that queried from a stored routine or
a prepared statement and this temporary table is dropped between
executions of SP/PS, then it leads to hitting an assertion
at the SELECT_LEX::fix_prepare_information. The fired assertion
was added by the commit 85f2e4f8e8
(MDEV-32466: Potential memory leak on executing of create view statement).
Firing of this assertion means memory leaking on execution of SP/PS.
Moreover, if the added assert be commented out, different result sets
can be produced by the statement SELECT * FROM the hidden table.
Both hitting the assertion and different result sets have the same root
cause. This cause is usage of temporary table's metadata after the table
itself has been dropped. To fix the issue, reload the cache of stored
routines. To do it cache of stored routines is reset at the end of
execution of the function dispatch_command(). Next time any stored routine
be called it will be loaded from the table mysql.proc. This happens inside
the method Sp_handler::sp_cache_routine where loading of a stored routine
is performed in case it missed in cache. Loading is performed unconditionally
while previously it was controlled by the parameter lookup_only. By that
reason the signature of the method Sroutine_hash_entry::sp_cache_routine
was changed by removing unused parameter lookup_only.
Clearing of sp caches affects the test main.lock_sync since it forces
opening and locking the table mysql.proc but the test assumes that each
statement locks its tables once during its execution. To keep this invariant
the debug sync points with names "before_lock_tables_takes_lock" and
"after_lock_tables_takes_lock" are not activated on handling the table
mysql.proc
Under terms of MDEV 27490 we'll add support for non-BMP identifiers
and upgrade casefolding information to Unicode version 14.0.0.
In Unicode-14.0.0 conversion to lower and upper cases can increase octet length
of the string, so conversion won't be possible in-place any more.
This patch removes virtual functions performing in-place casefolding:
- my_charset_handler_st::casedn_str()
- my_charset_handler_st::caseup_str()
and fixes the code to use the non-inplace functions instead:
- my_charset_handler_st::casedn()
- my_charset_handler_st::caseup()
Problem:
REPAIR TABLE executed for a pre-MDEV-29959 table (with the old UUID format)
updated the server version in the FRM file without rewriting the data,
so it created a new FRM for old UUIDs. After that MariaDB could not
read UUIDs correctly.
Fix:
- Adding a new virtual method in class Type_handler:
virtual bool type_handler_for_implicit_upgrade() const;
* For the up-to-date data types it returns "this".
* For the data types which need to be implicitly upgraded
during REPAIR TABLE or ALTER TABLE, it returns a pointer
to a new replacement data type handler.
Old VARCHAR and old UUID type handlers override this method.
See more comments below.
- Changing the semantics of the method
Type_handler::Column_definition_implicit_upgrade(Column_definition *c)
to the opposite, so now:
* c->type_handler() references the old data type (to upgrade from)
* "this" references the new data type (to upgrade to).
Before this change Column_definition_implicit_upgrade() was supposed
to be called with the old data type handler (to upgrade from).
Renaming the method to Column_definition_implicit_upgrade_to_this(),
to avoid automatic merges in this method.
Reflecting this change in Create_field::upgrade_data_types().
- Replacing the hard-coded data type tests inside handler::check_old_types()
to a call for the new virtual method
Type_handler::type_handler_for_implicit_upgrade()
- Overriding Type_handler_fbt::type_handler_for_implicit_upgrade()
to call a new method FbtImpl::type_handler_for_implicit_upgrade().
Reasoning:
Type_handler_fbt is a template, so it has access only to "this".
So in case of UUID data types, the type handler for old UUID
knows nothing about the type handler of new UUID inside sql_type_fixedbin.h.
So let's have Type_handler_fbt delegate type_handler_for_implicit_upgrade()
to its Type_collection, which knows both new UUID and old UUID.
- Adding Type_collection_uuid::type_handler_for_implicit_upgrade().
It returns a pointer to the new UUID type handler.
- Overriding Type_handler_var_string::type_handler_for_implicit_upgrade()
to return a pointer to type_handler_varchar (true VARCHAR).
- Cleanup: these two methods:
handler::check_old_types()
handler::ha_check_for_upgrade()
were always called consequently.
So moving the call for check_old_types() inside ha_check_for_upgrade(),
and making check_old_types() private.
- Cleanup: removing the "bool varchar" parameter from fill_alter_inplace_info(),
as its not used any more.
Several points of synchronization during ALTER TABLE COPY looked identical
in the progress report query. Besides, if its the late lock upgrade stage,
the data would be:
STAGE 0
MAX_STAGE 0
PROGRESS 0.000
which looks irrelevant.
This patch moves thd_progress_deinit call after the last lock upgrade.
Also, for online alter, if there is nothing to replicate, the
progress and max_progress values would be 0, which discard the result data
on the side of sql_show, see processlist_callback in sql_show.cc.
So now the minimal max_progress will be 1. To avoid 0% progress in the
report, minimax progress value is also set to 1, so we will see 100% if
there's nothing to replicate.
This will allow selects pass until the rename/commit stage.
The lock is anyway upgraded to MDL_EXCLUSIVE later by the
wait_while_table_is_used call in mysql_alter_table.
The memory leak occurs on error when backup_reset_alter_copy_lock fails
with timeout. This leads to the alter rollback, but flush_unused is not
called.
Move table flushing on error handling to a single place and mind more
possible failures this time.
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>
mysql_prepare_alter_table(): Alter table should check whether
foreign key exists when it expected to exists and
report the error in early stage
dict_foreign_parse_drop_constraints(): Don't throw error if the
foreign key constraints doesn't exist when if exists is given
in the statement.
- Add selected tables as shared keys for CTAS certification
- Set proper security context on the replayer thread
- Disallow CTAS command retry
Signed-off-by: Julius Goryavsky <julius.goryavsky@mariadb.com>
The server doesn't use the enforced storage engine in ALTER TABLE
without ENGINE clause to avoid an unwanted engine change.
However, the server tries to use the enforced engine in CREATE
INDEX. As a result, the false positive error is raised. The server
should not apply the enforced engine in CREATE INDEX too.
