DELETE statement
Single-table delete ordered by a field that has a hash-type index
may cause an assertion failure or a crash.
An optimization added by the fix for the bug 36569 forced the
optimizer to use ORDER BY-compatible indices when applicable.
However, the existence of unsorted indices (HASH index algorithm
for some engines such as MEMORY/HEAP, NDB) was ignored.
The test_if_order_by_key function has been modified to skip
unsorted indices.
mysql-test/r/heap_hash.result:
Test case for bug #55472.
mysql-test/t/heap_hash.test:
Test case for bug #55472.
sql/sql_select.cc:
Bug #55472: Assertion failed in heap_rfirst function of hp_rfirst.c on
DELETE statement
The test_if_order_by_key function has been modified to skip
unsorted indices.
Remove dead and unused code.
Update to reflect the code review requests.
include/thr_lock.h:
Remove declarations for THR_LOCK_OWNER,
added along with the patch for sensitive cursors.
mysys/thr_lock.c:
Remove support for multiple thr_lock requestors
per THD.
sql/lock.cc:
Revert the patch that added support for sensitive cursors.
sql/sp_rcontext.cc:
Updated the use of mysql_open_cursor().
sql/sql_class.cc:
Move the instance of Server_side_cursor
from class Prepared_statement to class Statement.
sql/sql_class.h:
Move the isntance of Server_side_cursor
from class Prepared_statement to class
Statement.
Remove multiple lock_ids of thr_lock.
sql/sql_cursor.cc:
Remove Sensitive_cursor implementation.
sql/sql_cursor.h:
Remove declarations for sensitive cursors.
sql/sql_prepare.cc:
Move the declaration of instance of Server_side_cursor
from class Statement to class Prepared_statement,
where it's used.
sql/sql_select.cc:
Remove sensitive cursor support.
sql/sql_select.h:
Remove sensitive cursor support.
sql/sql_union.cc:
Remove sensitive cursor support.
check_join_cache_usage() by the change:
Revno: 2793
Revision Id: igor@askmonty.org-20091221022615-kx5ieiu0okmiupuc
Timestamp: Sun 2009-12-20 18:26:15 -0800
Backport into MariaDB-5.2 the following:
WL#2771 "Block Nested Loop Join and Batched Key Access Join"
For queries with order by clauses that employed filesort usage of
virtual column references in select lists could trigger assertion
failures. It happened because a wrong vcol_set bitmap was used for
filesort. It turned out that filesort required its own vcol_set bitmap.
Made management of the vcol_set bitmaps similar to the management
of the read_set and write_set bitmaps.
This assert checks that the server does not try to send OK to the
client if there has been some error during processing. This is done
to make sure that the error is in fact sent to the client.
The problem was that view errors during processing of WHERE conditions
in UPDATE statements where not detected by the update code. It therefore
tried to send OK to the client, triggering the assert.
The bug was only noticeable in debug builds.
This patch fixes the problem by making sure that the update code
checks for errors during condition processing and acts accordingly.
If the expression for a virtual column of table contained datetime
comparison then the execution of the second query that used this
virtual column caused a crash. It happened because the execution
of the first query that used this virtual column inserted a cached
item into the expression tree. The cached tree was allocated in
the statement memory while the expression tree was allocated in
the table memory.
Now the cached items that are inserted into expressions for virtual
columns with datetime comparisons are always allocated in the same
mem_root as the expressions for virtual columns. So now the inserted
cached items are valid for any queries that use these virtual columns.
The issue was that we didn't always check result of ha_rnd_init() which caused a problem for handlers that returned an error in this code.
- Changed prototype of ha_rnd_init() to ensure that we get a compile warning if result is not checked.
- Added ha_rnd_init_with_error() that prints error on failure.
- Checked all usage of ha_rnd_init() and ensure we generate an error message on failures.
- Changed init_read_record() to return 1 on failure.
sql/create_options.cc:
Fixed wrong printf
sql/event_db_repository.cc:
Check result from init_read_record()
sql/events.cc:
Check result from init_read_record()
sql/filesort.cc:
Check result from ha_rnd_init()
sql/ha_partition.cc:
Check result from ha_rnd_init()
sql/ha_partition.h:
Fixed compiler warning
sql/handler.cc:
Added ha_rnd_init_with_error()
Check result from ha_rnd_init()
sql/handler.h:
Added ha_rnd_init_with_error()
Changed prototype of ha_rnd_init() to ensure that we get a compile warning if result is not checked
sql/item_subselect.cc:
Check result from ha_rnd_init()
sql/log.cc:
Check result from ha_rnd_init()
sql/log_event.cc:
Check result from ha_rnd_init()
sql/log_event_old.cc:
Check result from ha_rnd_init()
sql/mysql_priv.h:
init_read_record() now returns error code on failure
sql/opt_range.cc:
Check result from ha_rnd_init()
sql/records.cc:
init_read_record() now returns error code on failure
Check result from ha_rnd_init()
sql/sql_acl.cc:
Check result from init_read_record()
sql/sql_cursor.cc:
Print error if ha_rnd_init() fails
sql/sql_delete.cc:
Check result from init_read_record()
sql/sql_help.cc:
Check result from init_read_record()
sql/sql_plugin.cc:
Check result from init_read_record()
sql/sql_select.cc:
Check result from ha_rnd_init()
Print error if ha_rnd_init() fails.
sql/sql_servers.cc:
Check result from init_read_record()
sql/sql_table.cc:
Check result from init_read_record()
sql/sql_udf.cc:
Check result from init_read_record()
sql/sql_update.cc:
Check result from init_read_record()
storage/example/ha_example.cc:
Don't return error on rnd_init()
storage/ibmdb2i/ha_ibmdb2i.cc:
Removed not relevant comment
1. Changed the lazy optimization for subqueries that can be
materialized into bottom-up optimization during the optimization of
the main query.
The main change is implemented by the method
Item_in_subselect::setup_engine.
All other changes were required to correct problems resulting from
changing the order of optimization. Most of these problems followed
the same pattern - there are some shared structures between a
subquery and its parent query. Depending on which one is optimized
first (parent or child query), these shared strucutres may get
different values, thus resulting in an inconsistent query plan.
2. Changed the code-generation for subquery materialization to be
performed in runtime memory for each (re)execution, instead of in
statement memory (once per prepared statement).
- Item_in_subselect::setup_engine() no longer creates materialization
related objects in statement memory.
- Merged subselect_hash_sj_engine::init_permanent and
subselect_hash_sj_engine::init_runtime into
subselect_hash_sj_engine::init, which is called for each
(re)execution.
- Fixed deletion of the temp table accordingly.
mysql-test/r/subselect_mat.result:
Adjusted changed EXPLAIN because of earlier optimization of subqueries.
subquery execution, where the the REF buffer format was mistaken to
be in record format instead of key format. The error was that the null
byte for all fields of the record was in the front of the buffer,
and not before each field data.
libmysqld/Makefile.am:
The new file added.
mysql-test/r/index_merge_myisam.result:
subquery_cache optimization option added.
mysql-test/r/myisam_mrr.result:
subquery_cache optimization option added.
mysql-test/r/subquery_cache.result:
The subquery cache tests added.
mysql-test/r/subselect3.result:
Subquery cache switched off to avoid changing read statistics.
mysql-test/r/subselect3_jcl6.result:
Subquery cache switched off to avoid changing read statistics.
mysql-test/r/subselect_no_mat.result:
subquery_cache optimization option added.
mysql-test/r/subselect_no_opts.result:
subquery_cache optimization option added.
mysql-test/r/subselect_no_semijoin.result:
subquery_cache optimization option added.
mysql-test/r/subselect_sj.result:
subquery_cache optimization option added.
mysql-test/r/subselect_sj_jcl6.result:
subquery_cache optimization option added.
mysql-test/t/subquery_cache.test:
The subquery cache tests added.
mysql-test/t/subselect3.test:
Subquery cache switched off to avoid changing read statistics.
sql/CMakeLists.txt:
The new file added.
sql/Makefile.am:
The new files added.
sql/item.cc:
Expression cache item (Item_cache_wrapper) added.
Item_ref and Item_field fixed for correct usage of result field and fast resolwing in SP.
sql/item.h:
Expression cache item (Item_cache_wrapper) added.
Item_ref and Item_field fixed for correct usage of result field and fast resolwing in SP.
sql/item_cmpfunc.cc:
Subquery cache added.
sql/item_cmpfunc.h:
Subquery cache added.
sql/item_subselect.cc:
Subquery cache added.
sql/item_subselect.h:
Subquery cache added.
sql/item_sum.cc:
Registration of subquery parameters added.
sql/mysql_priv.h:
subquery_cache optimization option added.
sql/mysqld.cc:
subquery_cache optimization option added.
sql/opt_range.cc:
Fix due to subquery cache.
sql/opt_subselect.cc:
Parameters of the function cahnged.
sql/procedure.h:
.h file guard added.
sql/sql_base.cc:
Registration of subquery parameters added.
sql/sql_class.cc:
Option to allow add indeces to temporary table.
sql/sql_class.h:
Item iterators added.
Option to allow add indeces to temporary table.
sql/sql_expression_cache.cc:
Expression cache for caching subqueries added.
sql/sql_expression_cache.h:
Expression cache for caching subqueries added.
sql/sql_lex.cc:
Registration of subquery parameters added.
sql/sql_lex.h:
Registration of subqueries and subquery parameters added.
sql/sql_select.cc:
Subquery cache added.
sql/sql_select.h:
Subquery cache added.
sql/sql_union.cc:
A new parameter to the function added.
sql/sql_update.cc:
A new parameter to the function added.
sql/table.cc:
Procedures to manage temporarty tables index added.
sql/table.h:
Procedures to manage temporarty tables index added.
storage/maria/ha_maria.cc:
Fix of handler to allow destoy a table in case of error during the table creation.
storage/maria/ha_maria.h:
.h file guard added.
storage/myisam/ha_myisam.cc:
Fix of handler to allow destoy a table in case of error during the table creation.
The problem there is that HAVING condition evaluates const
parts of condition despite the condition has references
on aggregate functions. Table t1 became const tables
after make_join_statistics and table1.pk = 1, HAVING is
transformed into MAX(1) < 7 and taken away from HAVING.
The fix is to skip evaluation of HAVING conts parts if
HAVING condition has references on aggregate functions.
mysql-test/r/having.result:
test case
mysql-test/t/having.test:
test case
sql/sql_select.cc:
skip evaluation of HAVING conts parts if
HAVING condition has references on aggregate functions.
Essentially, the problem is that safemalloc is excruciatingly
slow as it checks all allocated blocks for overrun at each
memory management primitive, yielding a almost exponential
slowdown for the memory management functions (malloc, realloc,
free). The overrun check basically consists of verifying some
bytes of a block for certain magic keys, which catches some
simple forms of overrun. Another minor problem is violation
of aliasing rules and that its own internal list of blocks
is prone to corruption.
Another issue with safemalloc is rather the maintenance cost
as the tool has a significant impact on the server code.
Given the magnitude of memory debuggers available nowadays,
especially those that are provided with the platform malloc
implementation, maintenance of a in-house and largely obsolete
memory debugger becomes a burden that is not worth the effort
due to its slowness and lack of support for detecting more
common forms of heap corruption.
Since there are third-party tools that can provide the same
functionality at a lower or comparable performance cost, the
solution is to simply remove safemalloc. Third-party tools
can provide the same functionality at a lower or comparable
performance cost.
The removal of safemalloc also allows a simplification of the
malloc wrappers, removing quite a bit of kludge: redefinition
of my_malloc, my_free and the removal of the unused second
argument of my_free. Since free() always check whether the
supplied pointer is null, redudant checks are also removed.
Also, this patch adds unit testing for my_malloc and moves
my_realloc implementation into the same file as the other
memory allocation primitives.
client/mysqldump.c:
Pass my_free directly as its signature is compatible with the
callback type -- which wasn't the case for free_table_ent.
- Item_in_subselect::init_left_expr_cache() should not try to
guess whether the left expression is accessed "over the grouping operation"
(i.e. the subselect is evaluated after the grouping while the left_expr is
an Item_ref that wraps an expression from before the grouping). Instead,
let new_Cached_item not to try accessing item->real_item() when creating
left expr cache.
The problem is that QUICK_SELECT_DESC behaviour depends
on used_key_parts value which can be bigger than selected
best_key_parts value if an engine supports clustered key.
But used_key_parts is overwritten with best_key_parts
value that prevents from correct selection of index
access method. The fix is to preserve used_key_parts
value for further use in QUICK_SELECT_DESC.
mysql-test/r/innodb_mysql.result:
test case
mysql-test/t/innodb_mysql.test:
test case
sql/sql_select.cc:
preserve used_key_parts value for further use in QUICK_SELECT_DESC
- fix a bug in LooseScan strategy execution code (exposed by changing costs/QEP)
- Do set join_tab->sorted=TRUE for JOIN_TABs that use LooseScan (partitioning
handler cares about "sorted" parameter of h->index_init() call)
file .\filesort.cc, line 149 (part II)
Problem: the server didn't disregard sort order
for some zero length tuples.
Fix: skip sort order in such a case
(zero length NOT NULL string functions).
mysql-test/r/select.result:
Fix for bug #54459: Assertion failed: param.sort_length,
file .\filesort.cc, line 149 (part II)
- test result.
mysql-test/t/select.test:
Fix for bug #54459: Assertion failed: param.sort_length,
file .\filesort.cc, line 149 (part II)
- test case.
sql/sql_select.cc:
Fix for bug #54459: Assertion failed: param.sort_length,
file .\filesort.cc, line 149 (part II)
- disregard sort order for zero length NOT NULL string functions
along with zero length NOT NULL fields.
Don't call member functions for a NIL pointer.
mysql-test/r/subselect4.result:
Add test case.
mysql-test/t/subselect4.test:
Add test case.
sql/sql_select.cc:
If the (virtual) member function clone_item() returns NULL,
there is no substitution to be made, and we don't need to set the collation.
The test was invoking Item_cache::clone_item()
use limit efficiently
Bug #36569: UPDATE ... WHERE ... ORDER BY... always does a
filesort even if not required
Also two bugs reported after QA review (before the commit
of bugs above to public trees, no documentation needed):
Bug #53737: Performance regressions after applying patch
for bug 36569
Bug #53742: UPDATEs have no effect after applying patch
for bug 36569
Execution of single-table UPDATE and DELETE statements did not use the
same optimizer as was used in the compilation of SELECT statements.
Instead, it had an optimizer of its own that did not take into account
that you can omit sorting by retrieving rows using an index.
Extra optimization has been added: when applicable, single-table
UPDATE/DELETE statements use an existing index instead of filesort. A
corresponding SELECT query would do the former.
Also handling of the DESC ordering expression has been added when
reverse index scan is applicable.
From now on most single table UPDATE and DELETE statements show the
same disk access patterns as the corresponding SELECT query. We verify
this by comparing the result of SHOW STATUS LIKE 'Sort%
Currently the get_index_for_order function
a) checks quick select index (if any) for compatibility with the
ORDER expression list or
b) chooses the cheapest available compatible index, but only if
the index scan is cheaper than filesort.
Second way is implemented by the new test_if_cheaper_ordering
function (extracted part the test_if_skip_sort_order()).
mysql-test/r/log_state.result:
Updated result for optimized query, bug #36569.
mysql-test/r/single_delete_update.result:
Test case for bug #30584, bug #36569 and bug #53742.
mysql-test/r/update.result:
Updated result for optimized query, bug #30584.
Note:
"Handler_read_last 1" omitted, see bug 52312:
lost Handler_read_last status variable.
mysql-test/t/single_delete_update.test:
Test case for bug #30584, bug #36569 and bug #53742.
sql/opt_range.cc:
Bug #30584, bug #36569: UPDATE/DELETE ... WHERE ... ORDER BY...
always does a filesort even if not required
* get_index_for_order() has been rewritten entirely and moved
to sql_select.cc
New QUICK_RANGE_SELECT::make_reverse method has been added.
sql/opt_range.h:
Bug #30584, bug #36569: UPDATE/DELETE ... WHERE ... ORDER BY...
always does a filesort even if not required
* get_index_for_order() has been rewritten entirely and moved
to sql_select.cc
New functions:
* QUICK_SELECT_I::make_reverse()
* SQL_SELECT::set_quick()
sql/records.cc:
Bug #30584, bug #36569: UPDATE/DELETE ... WHERE ... ORDER BY...
always does a filesort even if not required
* init_read_record_idx() has been modified to allow reverse index scan
New functions:
* rr_index_last()
* rr_index_desc()
sql/records.h:
Bug #30584, bug #36569: UPDATE/DELETE ... WHERE ... ORDER BY...
always does a filesort even if not required
init_read_record_idx() has been modified to allow reverse index scan
sql/sql_delete.cc:
Bug #30584, bug #36569: UPDATE/DELETE ... WHERE ... ORDER BY...
always does a filesort even if not required
mysql_delete: an optimization has been added to skip
unnecessary sorting with ORDER BY clause where select
result ordering is acceptable.
sql/sql_select.cc:
Bug #30584, bug #36569, bug #53737, bug #53742:
UPDATE/DELETE ... WHERE ... ORDER BY... always does a filesort
even if not required
The const_expression_in_where function has been modified
to accept both Item and Field pointers.
New functions:
* get_index_for_order()
* test_if_cheaper_ordering() has been extracted from
test_if_skip_sort_order() to share with get_index_for_order()
* simple_remove_const()
sql/sql_select.h:
Bug #30584, bug #36569: UPDATE/DELETE ... WHERE ... ORDER BY...
always does a filesort even if not required
New functions:
* test_if_cheaper_ordering()
* simple_remove_const()
* get_index_for_order()
sql/sql_update.cc:
Bug #30584, bug #36569: UPDATE/DELETE ... WHERE ... ORDER BY...
always does a filesort even if not required
mysql_update: an optimization has been added to skip
unnecessary sorting with ORDER BY clause where a select
result ordering is acceptable.
sql/table.cc:
Bug #30584, bug #36569: UPDATE/DELETE ... WHERE ... ORDER BY...
always does a filesort even if not required
New functions:
* TABLE::update_const_key_parts()
* is_simple_order()
sql/table.h:
Bug #30584, bug #36569: UPDATE/DELETE ... WHERE ... ORDER BY...
always does a filesort even if not required
New functions:
* TABLE::update_const_key_parts()
* is_simple_order()
strict aliasing violations.
One somewhat major source of strict-aliasing violations and
related warnings is the SQL_LIST structure. For example,
consider its member function `link_in_list` which takes
a pointer to pointer of type T (any type) as a pointer to
pointer to unsigned char. Dereferencing this pointer, which
is done to reset the next field, violates strict-aliasing
rules and might cause problems for surrounding code that
uses the next field of the object being added to the list.
The solution is to use templates to parametrize the SQL_LIST
structure in order to deference the pointers with compatible
types. As a side bonus, it becomes possible to remove quite
a few casts related to acessing data members of SQL_LIST.
sql/handler.h:
Use the appropriate template type argument.
sql/item.cc:
Remove now-unnecessary cast.
sql/item_subselect.cc:
Remove now-unnecessary casts.
sql/item_sum.cc:
Use the appropriate template type argument.
Remove now-unnecessary cast.
sql/mysql_priv.h:
Move SQL_LIST structure to sql_list.h
Use the appropriate template type argument.
sql/sp.cc:
Remove now-unnecessary casts.
sql/sql_delete.cc:
Use the appropriate template type argument.
Remove now-unnecessary casts.
sql/sql_derived.cc:
Remove now-unnecessary casts.
sql/sql_lex.cc:
Remove now-unnecessary casts.
sql/sql_lex.h:
SQL_LIST now takes a template type argument which must
match the type of the elements of the list. Use forward
declaration when the type is not available, it is used
in pointers anyway.
sql/sql_list.h:
Rename SQL_LIST to SQL_I_List. The template parameter is
the type of object that is stored in the list.
sql/sql_olap.cc:
Remove now-unnecessary casts.
sql/sql_parse.cc:
Remove now-unnecessary casts.
sql/sql_prepare.cc:
Remove now-unnecessary casts.
sql/sql_select.cc:
Remove now-unnecessary casts.
sql/sql_show.cc:
Remove now-unnecessary casts.
sql/sql_table.cc:
Remove now-unnecessary casts.
sql/sql_trigger.cc:
Remove now-unnecessary casts.
sql/sql_union.cc:
Remove now-unnecessary casts.
sql/sql_update.cc:
Remove now-unnecessary casts.
sql/sql_view.cc:
Remove now-unnecessary casts.
sql/sql_yacc.yy:
Remove now-unnecessary casts.
storage/myisammrg/ha_myisammrg.cc:
Remove now-unnecessary casts.
- Unify EXPLAIN printout for <subqueryN> tables with regular tables
- Update test results for <subqueryN> tables:
s/unique_key/distinct_key/g
s/1.0/100.0/ for "filtered" column
- Make join buffering take into account that join_tabs are not a
single linear array anymore
- Remove outer join + SJ-Materialization crash (OJ+SJ the processing
is most likely still incorrect)
* remove handler::index_read_last()
* create handler::keyread_read_time() (was get_index_only_read_time() in opt_range.cc)
* ha_show_status() allows engine's show_status() to fail
* remove HTON_FLUSH_AFTER_RENAME
* fix key_cmp_if_same() to work for floats and doubles
* set table->status in the server, don't force engines to do it
* increment status vars in the server, don't force engines to do it
mysql-test/r/status_user.result:
correct test results - innodb was wrongly counting internal
index searches as handler_read_* calls.
sql/ha_partition.cc:
compensate for handler incrementing status counters -
we want to count only calls to underlying engines
sql/handler.h:
inline methods moved to sql_class.h
sql/key.cc:
simplify the check
sql/opt_range.cc:
move get_index_only_read_time to the handler class
sql/sp.cc:
don't use a key that's stored in the record buffer -
the engine can overwrite the buffer with anything, destroying the key
sql/sql_class.h:
inline handler methods that need to see THD and TABLE definitions
sql/sql_select.cc:
no ha_index_read_last_map anymore
sql/sql_table.cc:
remove HTON_FLUSH_AFTER_RENAME
sql/table.cc:
set HA_CAN_MEMCMP as appropriate
sql/tztime.cc:
don't use a key that's stored in the record buffer -
the engine can overwrite the buffer with anything, destroying the key
storage/myisam/ha_myisam.cc:
engines don't need to update table->status or use ha_statistic_increment anymore
storage/myisam/ha_myisam.h:
index_read_last_map is no more