This is a non-functional change and should not change the server behavior.
Casefolding information is now stored in items of a new data type MY_CASEFOLD_CHARACTER:
typedef struct casefold_info_char_t
{
uint32 toupper;
uint32 tolower;
} MY_CASEFOLD_CHARACTER;
Before this change, casefolding tables for Asian collations were stored in:
typedef struct unicase_info_char_st
{
uint32 toupper;
uint32 tolower;
uint32 sort;
} MY_UNICASE_CHARACTER;
The "sort" member was not used in the code handling Asian collations,
it only wasted space.
(it's only used by Unicode _general_ci and _general_mysql500_ci collations).
Unicode collations (at least UCA and _bin) should also be refactored later,
but under terms of a separate task.
String length growth during upper/lower conversion
in Unicode collations depends only on the underlying MY_UNICASE_INFO
used in the collation.
Maintaining a separate member CHARSET_INFO::caseup_multiply and
CHARSET_INFO::casedn_multiply duplicated this information
and caused bugs like this (when MY_UNICASE_INFO and case??_multiply
when out of sync because of incomplete CHARSET_INFO initialization).
Fix:
Changing CHARSET_INFO::caseup_multiply and CHARSET_INFO::casedn_multiply
from members to virtual functions.
The virtual functions in Unicode collations calculate case conversion
growth factors from the MY_UNICASE_INFO. This guarantees that the growth
factors are always in sync with the MY_UNICASE_INFO.
avoid contaminating my_getopt with sysvar implementation details.
adjust variable values after my_getopt, like it's done for others.
this fixes --help to show correct values.
Eventually mysql symlinks will go away, as MariaDB and MySQL keep
diverging and we do not want to make it impossible to install
MariaDB and MySQL side-by-side when users want it.
It also useful if people start using MariaDB tools with MariaDB.
If the exe doesn't begine with "mariadb" or is a symlink,
print a warning to use the resolved name.
In my_readlink, add check on my_thread_var as its used by comp_err
and other build utils that also use my_init.
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".
This includes:
- cleanup and optimization of filtering and pushdown engine code.
- Adjusted costs for rowid filters (based on extensive testing
and profiling).
This made a small two changes to the handler_rowid_filter_is_active()
API:
- One should not call it with a zero pointer!
- One does not need to call handler_rowid_filter_is_active() for every
row anymore. It is enough to check if filter is active by calling it
call it during index_init() or when handler::rowid_filter_changed()
is called
The changes was to avoid unnecessary function calls and checks if
pushdown conditions and rowid_filter is not used.
Updated costs for rowid_filter_lookup() to be closer to reality.
The old cost was based only on rowid_compare_cost. This is now
changed to take into account the overhead in checking the rowid.
Changed the Range_rowid_filter class to use DYNAMIC_ARRAY directly
instead of Dynamic_array<>. This was done to be able to use the new
append_dynamic() functions which gives a notable speed improvment
compared to the old code. Removing the abstraction also makes
the code easier to understand.
The cost of filtering is now slightly lower than before, which
is reflected in some test cases that is now using rowid filters.
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)
- introduce table key construction function in wsrep service interface
- don't add row keys when replicating bulk insert
- don't start bulk insert on applier or when transaction is not active
- don't start bulk insert on system versioned tables
- implement actual bulk insert table-level key replication
Reviewed-by: Jan Lindström <jan.lindstrom@mariadb.com>
The MariaDB code base uses strcat() and strcpy() in several
places. These are known to have memory safety issues and their usage is
discouraged. Common security scanners like Flawfinder flags them. In MariaDB we
should start using modern and safer variants on these functions.
This is similar to memory issues fixes in 19af1890b5
and 9de9f105b5 but now replace use of strcat()
and strcpy() with safer options strncat() and strncpy().
However, add '\0' forcefully to make sure the result string is correct since
for these two functions it is not guaranteed what new string will be null-terminated.
Example:
size_t dest_len = sizeof(g->Message);
strncpy(g->Message, "Null json tree", dest_len); strncat(g->Message, ":",
sizeof(g->Message) - strlen(g->Message)); size_t wrote_sz = strlen(g->Message);
size_t cur_len = wrote_sz >= dest_len ? dest_len - 1 : wrote_sz;
g->Message[cur_len] = '\0';
All new code of the whole pull request, including one or several files
that are either new files or modified ones, are contributed under the BSD-new
license. I am contributing on behalf of my employer Amazon Web Services
-- Reviewer and co-author Vicențiu Ciorbaru <vicentiu@mariadb.org>
-- Reviewer additions:
* The initial function implementation was flawed. Replaced with a simpler
and also correct version.
* Simplified code by making use of snprintf instead of chaining strcat.
* Simplified code by removing dynamic string construction in the first
place and using static strings if possible. See connect storage engine
changes.
try to make them less confusing for users.
Hopefully, if the version string will be changed like
- mariadb Ver 15.1 Distrib 10.11.2-MariaDB for Linux (x86_64)
+ mariadb from 10.11.2-MariaDB, client 15.1 for Linux (x86_64)
users will be less inclined to reply "15.1" to the question
"what mariadb version are you using?"
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.
