- Adding a helper function append_identifier_opt_casedn()
- Reusing it in:
Item_ident::print()
Item_func_nextval::print()
Item_func_setval::print()
This change remove six my_casedn_str() calls and reduces the code size.
- Replacing the old style inplace check_db_name() in make_table_name_list()
to the new style non-modifying code
- Adding "const" qualifier to the "db" parameter to ha_discover_table_names()
and its dependency functions.
it was redundant, duplicating vcol_type == VCOL_GENERATED_STORED.
Note that VCOL_DEFAULT is not "stored", "stored vcol" means that after
rnd_next or index_read/etc the field value is already in the record[0]
and does not need to be calculated separately
- Pre-open temporary table on sequence creation.
- Without this patch, if rename alter is done on the temporary sequence,
and after that `create replace`, since table is not preopened and
alter rename marked the table as reopen, and such table is deleted in
the `find_temporary_table()` leaving the share without the table, that
causes `show tables` to fail
- Closes PR #2685
- Reviewer: <serg@mariadb.com>
* IS_USER_TEMP_TABLE() was misleading, name didn't match the code
* list of temp tables was rescanned number_of_databases times
* some temporary tables were not shown (from nonexistent databases)
* some temporary tables were shown more than once (e.g. after self-joins)
* sys.table_exists() - avoid querying I_S twice
* fix handling of temporary MERGE tables - it's pointless to fully open
them, they're not in thd->temporary_tables, so they simply fail to
open and are skipped. Relax the assertion instead.
Additionally fixes the bugs uncovered in:
- `MDEV-28332: Alter on temporary table causes ER_TABLE_EXISTS_ERROR note`
Since there is no `warning` issued by shadowing of base table, this MDEV
is irrelevant. Keeping for review purposes and for future development
in case shadowing is going to be implemented
- `MDEV-28334: SHOW TABLE STATUS shows all temporary tables ignoring database and conditions`
- `MDEV-28453: SHOW commands are inconsistent for temporary tables`
Reviewed by: <monty@mariadb.org>,
<vicentiu@mariadb.org>
This patch adds a way to override default collations
(or "character set collations") for desired character sets.
The SQL standard says:
> Each collation known in an SQL-environment is applicable to one
> or more character sets, and for each character set, one or more
> collations are applicable to it, one of which is associated with
> it as its character set collation.
In MariaDB, character set collations has been hard-coded so far,
e.g. utf8mb4_general_ci has been a hard-coded character set collation
for utf8mb4.
This patch allows to override (globally per server, or per session)
character set collations, so for example, uca1400_ai_ci can be set as a
character set collation for Unicode character sets
(instead of compiled xxx_general_ci).
The array of overridden character set collations is stored in a new
(session and global) system variable @@character_set_collations and
can be set as a comma separated list of charset=collation pairs, e.g.:
SET @@character_set_collations='utf8mb3=uca1400_ai_ci,utf8mb4=uca1400_ai_ci';
The variable is empty by default, which mean use the hard-coded
character set collations (e.g. utf8mb4_general_ci for utf8mb4).
The variable can also be set globally by passing to the server startup command
line, and/or in my.cnf.
The effect was that that ROOT_FLAG_THREAD_SPECIFIC was cleared and
the memory allocated by memroot would be contributed the the system,
not to the thread.
This exposed a bug in how "show explain for ..." allocated data.
- The thread that did provide the explain allocated data in the
"show explain" threads mem_root, which is marked as THREAD_SPECIFIC.
- Fixed by allocating the explain data in a temporary explain_mem_root
which is not THREAD_SPECIFIC.
Other things:
- Added extra checks when using update_malloc_size()
- Do not call update_malloc_size() for memory not registered with
update_malloc_size(). This avoid some wrong 'memory not freed' reports.
- Added a checking of 'thd->killed' to ensure that
main.truncate_notembedded.test still works.
Reported by: Yury Chaikou
The code in create_internal_tmp_table() didn't take into account that
now temporary (derived) tables may have multiple indexes:
- one index due to duplicate removal
= In this example created by conversion of big-IN(...) into subquery
= this index might be converted into a "unique constraint" if the key
length is too large.
- one index added by derived_with_keys optimization.
Make create_internal_tmp_table() handle multiple indexes.
Before this patch, use of a unique constraint was indicated in
TABLE_SHARE::uniques. This was ok as unique constraint was the only index
in the table. Now it's no longer the case so TABLE_SHARE::uniques is removed
and replaced with an in-memory-only flag HA_UNIQUE_HASH.
This patch is based on Monty's patch.
Co-Author: Monty <monty@mariadb.org>
Subselect_single_value_engine cannot handle table value constructor used as
subquery. That's why any table value constructor TVC used as subquery is
converted into a select over derived table whose specification is TVC.
Currently the names of the columns of the derived table DT are taken from
the first element of TVC and if the k-th component of the element happens
to be a subquery the text representation of this subquery serves as the
name of the k-th column of the derived table. References of all columns of
the derived table DT compose the select list of the result of the conversion.
If a definition of a view contained a table value constructor used as a
subquery and the view was registered after this conversion had been
applied we could register an invalid view definition if the first element
of TVC contained a subquery as its component: the name of this component
was taken from the original subquery, while the name of the corresponding
column of the derived table was taken from the text representation of the
subquery produced by the function SELECT_LEX::print() and these names were
usually differ from each other.
To avoid registration of such invalid views the function SELECT_LEX::print()
now prints the original TVC instead of the select in which this TVC has
been wrapped. Now the specification of registered view looks like as if no
conversions from TVC to selects were done.
Approved by Oleksandr Byelkin <sanja@mariadb.com>
This patch also fixes some bugs detected by valgrind after this
patch:
- Not enough copy_func elements was allocated by Create_tmp_table() which
causes an memory overwrite in Create_tmp_table::add_fields()
I added an ASSERT() to be able to detect this also without valgrind.
The bug was that TMP_TABLE_PARAM::copy_fields was not correctly set
when calling create_tmp_table().
- Aria::empty_bits is not allocated if there is no varchar/char/blob
fields in the table. Fixed code to take this into account.
This cannot cause any issues as this is just a memory access
into other Aria memory and the content of the memory would not be used.
- Aria::last_key_buff was not allocated big enough. This may have caused
issues with rtrees and ma_extra(HA_EXTRA_REMEMBER_POS) as they
would use the same memory area.
- Aria and MyISAM didn't take extended key parts into account, which
caused problems when copying rec_per_key from engine to sql level.
- Mark asan builds with 'asan' in version strihng to detect these in
not_valgrind_build.inc.
This is needed to not have main.sp-no-valgrind fail with asan.
Added comments that not used keys of derivied tables will be deleted.
Added some comments about checking if pos_in_table_list is 0.
Other things:
- Added a marker (DBTYPE_IN_PREDICATE) in TABLE_LIST->derived_type
to indicate that the table was generated from IN (list). This is
useful for debugging and can later be used by explain if needed.
- Removed a not needed test of table->pos_in_table_list as it should
always be valid at this point in time.
This patch is the result of running
run-clang-tidy -fix -header-filter=.* -checks='-*,modernize-use-equals-default' .
Code style changes have been done on top. The result of this change
leads to the following improvements:
1. Binary size reduction.
* For a -DBUILD_CONFIG=mysql_release build, the binary size is reduced by
~400kb.
* A raw -DCMAKE_BUILD_TYPE=Release reduces the binary size by ~1.4kb.
2. Compiler can better understand the intent of the code, thus it leads
to more optimization possibilities. Additionally it enabled detecting
unused variables that had an empty default constructor but not marked
so explicitly.
Particular change required following this patch in sql/opt_range.cc
result_keys, an unused template class Bitmap now correctly issues
unused variable warnings.
Setting Bitmap template class constructor to default allows the compiler
to identify that there are no side-effects when instantiating the class.
Previously the compiler could not issue the warning as it assumed Bitmap
class (being a template) would not be performing a NO-OP for its default
constructor. This prevented the "unused variable warning".
SUPER privilege used to allow various actions that were alternatively
allowed by one of BINLOG ADMIN, BINLOG MONITOR, BINLOG REPLAY,
CONNECTION ADMIN, FEDERATED ADMIN, REPL MASTER ADMIN, REPL SLAVE ADMIN,
SET USER, SLAVE MONITOR.
Now SUPER no longer does that, one has to grant one of the fine-grained
privileges above to be to perform corresponding actions.
On upgrade from MariaDB versions 10.11 and below all the privileges
above are granted automatically if the user has SUPER.
As a side-effect, such an upgrade will allow SUPER-user to run SHOW
BINLOG EVENTS, SHOW RELAYLOG EVENTS, SHOW SLAVE HOSTS, even if he wasn't
able to do it before the upgrade.
This makes it easier to compare different costs and also allows
the optimizer to optimizer different storage engines more reliably.
- Added tests/check_costs.pl, a tool to verify optimizer cost calculations.
- Most engine costs has been found with this program. All steps to
calculate the new costs are documented in Docs/optimizer_costs.txt
- User optimizer_cost variables are given in microseconds (as individual
costs can be very small). Internally they are stored in ms.
- Changed DISK_READ_COST (was DISK_SEEK_BASE_COST) from a hard disk cost
(9 ms) to common SSD cost (400MB/sec).
- Removed cost calculations for hard disks (rotation etc).
- Changed the following handler functions to return IO_AND_CPU_COST.
This makes it easy to apply different cost modifiers in ha_..time()
functions for io and cpu costs.
- scan_time()
- rnd_pos_time() & rnd_pos_call_time()
- keyread_time()
- Enhanched keyread_time() to calculate the full cost of reading of a set
of keys with a given number of ranges and optional number of blocks that
need to be accessed.
- Removed read_time() as keyread_time() + rnd_pos_time() can do the same
thing and more.
- Tuned cost for: heap, myisam, Aria, InnoDB, archive and MyRocks.
Used heap table costs for json_table. The rest are using default engine
costs.
- Added the following new optimizer variables:
- optimizer_disk_read_ratio
- optimizer_disk_read_cost
- optimizer_key_lookup_cost
- optimizer_row_lookup_cost
- optimizer_row_next_find_cost
- optimizer_scan_cost
- Moved all engine specific cost to OPTIMIZER_COSTS structure.
- Changed costs to use 'records_out' instead of 'records_read' when
recalculating costs.
- Split optimizer_costs.h to optimizer_costs.h and optimizer_defaults.h.
This allows one to change costs without having to compile a lot of
files.
- Updated costs for filter lookup.
- Use a better cost estimate in best_extension_by_limited_search()
for the sorting cost.
- Fixed previous issues with 'filtered' explain column as we are now
using 'records_out' (min rows seen for table) to calculate filtering.
This greatly simplifies the filtering code in
JOIN_TAB::save_explain_data().
This change caused a lot of queries to be optimized differently than
before, which exposed different issues in the optimizer that needs to
be fixed. These fixes are in the following commits. To not have to
change the same test case over and over again, the changes in the test
cases are done in a single commit after all the critical change sets
are done.
InnoDB changes:
- Updated InnoDB to not divide big range cost with 2.
- Added cost for InnoDB (innobase_update_optimizer_costs()).
- Don't mark clustered primary key with HA_KEYREAD_ONLY. This will
prevent that the optimizer is trying to use index-only scans on
the clustered key.
- Disabled ha_innobase::scan_time() and ha_innobase::read_time() and
ha_innobase::rnd_pos_time() as the default engine cost functions now
works good for InnoDB.
Other things:
- Added --show-query-costs (\Q) option to mysql.cc to show the query
cost after each query (good when working with query costs).
- Extended my_getopt with GET_ADJUSTED_VALUE which allows one to adjust
the value that user is given. This is used to change cost from
microseconds (user input) to milliseconds (what the server is
internally using).
- Added include/my_tracker.h ; Useful include file to quickly test
costs of a function.
- Use handler::set_table() in all places instead of 'table= arg'.
- Added SHOW_OPTIMIZER_COSTS to sys variables. These are input and
shown in microseconds for the user but stored as milliseconds.
This is to make the numbers easier to read for the user (less
pre-zeros). Implemented in 'Sys_var_optimizer_cost' class.
- In test_quick_select() do not use index scans if 'no_keyread' is set
for the table. This is what we do in other places of the server.
- Added THD parameter to Unique::get_use_cost() and
check_index_intersect_extension() and similar functions to be able
to provide costs to called functions.
- Changed 'records' to 'rows' in optimizer_trace.
- Write more information to optimizer_trace.
- Added INDEX_BLOCK_FILL_FACTOR_MUL (4) and INDEX_BLOCK_FILL_FACTOR_DIV (3)
to calculate usage space of keys in b-trees. (Before we used numeric
constants).
- Removed code that assumed that b-trees has similar costs as binary
trees. Replaced with engine calls that returns the cost.
- Added Bitmap::find_first_bit()
- Added timings to join_cache for ANALYZE table (patch by Sergei Petrunia).
- Added records_init and records_after_filter to POSITION to remember
more of what best_access_patch() calculates.
- table_after_join_selectivity() changed to recalculate 'records_out'
based on the new fields from best_access_patch()
Bug fixes:
- Some queries did not update last_query_cost (was 0). Fixed by moving
setting thd->...last_query_cost in JOIN::optimize().
- Write '0' as number of rows for const tables with a matching row.
Some internals:
- Engine cost are stored in OPTIMIZER_COSTS structure. When a
handlerton is created, we also created a new cost variable for the
handlerton. We also create a new variable if the user changes a
optimizer cost for a not yet loaded handlerton either with command
line arguments or with SET
@@global.engine.optimizer_cost_variable=xx.
- There are 3 global OPTIMIZER_COSTS variables:
default_optimizer_costs The default costs + changes from the
command line without an engine specifier.
heap_optimizer_costs Heap table costs, used for temporary tables
tmp_table_optimizer_costs The cost for the default on disk internal
temporary table (MyISAM or Aria)
- The engine cost for a table is stored in table_share. To speed up
accesses the handler has a pointer to this. The cost is copied
to the table on first access. If one wants to change the cost one
must first update the global engine cost and then do a FLUSH TABLES.
This was done to be able to access the costs for an open table
without any locks.
- When a handlerton is created, the cost are updated the following way:
See sql/keycaches.cc for details:
- Use 'default_optimizer_costs' as a base
- Call hton->update_optimizer_costs() to override with the engines
default costs.
- Override the costs that the user has specified for the engine.
- One handler open, copy the engine cost from handlerton to TABLE_SHARE.
- Call handler::update_optimizer_costs() to allow the engine to update
cost for this particular table.
- There are two costs stored in THD. These are copied to the handler
when the table is used in a query:
- optimizer_where_cost
- optimizer_scan_setup_cost
- Simply code in best_access_path() by storing all cost result in a
structure. (Idea/Suggestion by Igor)
The MDEV-25004 test innodb_fts.versioning is omitted because ever since
commit 685d958e38 InnoDB would not allow
writes to a database where the redo log file ib_logfile0 is missing.
