Analysis:
The following call stack shows that it is possible to set Item_cache::value_cached, and the relevant value
without setting Item_cache::example.
#0 Item_cache_temporal::store_packed at item.cc:8395
#1 get_datetime_value at item_cmpfunc.cc:915
#2 resolve_const_item at item.cc:7987
#3 propagate_cond_constants at sql_select.cc:12264
#4 propagate_cond_constants at sql_select.cc:12227
#5 optimize_cond at sql_select.cc:13026
#6 JOIN::optimize at sql_select.cc:1016
#7 st_select_lex::optimize_unflattened_subqueries at sql_lex.cc:3161
#8 JOIN::optimize_unflattened_subqueries at opt_subselect.cc:4880
#9 JOIN::optimize at sql_select.cc:1554
The fix is to set Item_cache_temporal::example even when the value is
set directly by Item_cache_temporal::store_packed. This makes the
Item_cache_temporal object consistent.
Using too long table aliases in stored routines might
have caused server crashes.
Code in sp_head::merge_table_list() which is responsible
for collecting information about tables used in stored
routine was not aware of the fact that table alias might
have arbitrary length. I.e. it assumed that table alias
can't be longer than NAME_LEN bytes and allocated buffer
for a key identifying table accordingly.
This patch fixes the issue by ensuring that we use
dynamically allocated buffer for table key when table
alias is too long. By default stack based buffer is used
in which NAME_LEN bytes are reserved for table alias.
taking a change done to main 5.1 by Dmitri Lenev.
This is the original comment:
> committer: Dmitry Lenev <Dmitry.Lenev@oracle.com>
> branch nick: mysql-5.1-15954896
> timestamp: Wed 2012-12-05 19:26:56 +0400
> message:
> Bug #15954896 "SP, MULTI-TABLE DELETE AND LONG ALIAS".
Using too long table aliases in stored routines might
have caused server crashes.
Code in sp_head::merge_table_list() which is responsible
for collecting information about tables used in stored
routine was not aware of the fact that table alias might
have arbitrary length. I.e. it assumed that table alias
can't be longer than NAME_LEN bytes and allocated buffer
for a key identifying table accordingly.
This patch fixes the issue by ensuring that we use
dynamically allocated buffer for table key when table
alias is too long. By default stack based buffer is used
in which NAME_LEN bytes are reserved for table alias.
The patch decreases the duration of LOCK_thread_count, so it is not hold during THD destructor and freeing memory.
This mutex now only protects the integrity of threads list, when removing THD from it, and thread_count variable.
The add_to_status() function that updates global status during client disconnect, is now correctly protected by the LOCK_status mutex.
Benchmark : in a "non-persistent" sysbench test (oltp_ro with reconnect after each query), ~ 25% more connects/disconnects were measured
Analysys:
In the beginning of JOIN::cleanup there is code that is supposed to
free all filesort buffers. The code assumes that the table being sorted
is the first non-constant table. To get this table it calls:
first_top_level_tab(this, WITHOUT_CONST_TABLES)
However, first_top_level_tab() instead returned the wrong table - the first
one in the plan, instead of the first non-constant table. There is no other
place outside filesort() where sort buffers may be freed. As a result, the
sort buffer was not freed, and there was a memory leak.
Solution:
Change first_top_level_tab(), to test for WITH_CONST_TABLES instead of
WITHOUT_CONST_TABLES.
mysql-test/r/create.result:
Updated test results
mysql-test/t/create.test:
Updated test
sql/sql_base.cc:
Use push_internal_handler/pop_internal_handler to avoid errors & warnings instead of clear_error
Give a warnings instead of an error for CREATE TABLE IF EXISTS
sql/sql_parse.cc:
Check if we failed because of table exists (can only happen from create)
sql/sql_table.cc:
Check if we failed because of table exists (can only happen from create)
Analysis:
The reason for the suboptimal plan when querying IS tables through a view
was that the view columns that participate in an equality are wrapped by
an Item_direct_view_ref and were not recognized as being direct column
references.
Solution:
Use the original Item_field objects via the real_item() method.
mysql-test/r/create.result:
Added test case to show that CREATE TABLE also is not waiting if table exists.
mysql-test/t/create.test:
Added test case to show that CREATE TABLE also is not waiting if table exists.
sql/sql_base.cc:
Clear also warnings from acquire_locks if we retry.
- Added option to check_if_table_exists() to quickly check if table exists (either SHARE or .FRM)
- Extended lock_table_names() to not wait for meta data locks if CREATE IF NOT EXISTS is used.
mysql-test/r/create.result:
New test case
mysql-test/t/create.test:
New test case
sql/sql_base.cc:
Added option to check_if_table_exists() to quickly check if table exists (either SHARE or .FRM)
Extended lock_table_names() to not wait for meta data locks if CREATE IF NOT EXISTS is used.
sql/sql_base.h:
Updated prototype
sql/sql_db.cc:
Added extra argument to call to check_if_table_exists()
Description: A very large database name causes buffer
overflow in functions acl_get() and
check_grant_db() in sql_acl.cc. It happens
due to an unguarded string copy operation.
This puts required sanity checks before
copying db string to destination buffer.
The failure is caused by failing stat() call . C Runtime function stat() uses old struct with 32bit st_size member,
and since Visual Studio 2010 , it returns an error on st_size overflow (i.e on files larger than 4GB)
Fix replaces stat() by my_stat(), the later is backed by 64bit-able stat64().
Code in MDL subsystem assumes that identifiers of objects can't
be longer than NAME_LEN characters. This assumption was broken
when one tried to construct MDL_key based on table alias, which
can have arbitrary length. Since MDL_key's (and MDL locks) are
not really used for table aliases this patch changes code to
not initialize MDL_key object for table list element representing
aliases.
The problem was that in debugging binaries it try to print item to assign human readable name to the item.
But subquery item was already freed (join_free/cleanup with full cleanup) so Item_field refers to temporary
table which memory had been already freed.
When inserting a record with update on duplicate keys the server calls
the ha_index_read_idx_map handler function to look for the record
that violates unique key constraints. The third parameter of this call
should mark only the base components of the index where the server is
searched for the record. Possible hidden components of the primary key
are to be unmarked.
Assertion happened because sql_kill did not set OK status in diagnostic area
in the case of connection suicide (id to kill == thd->thread_id), issued
via COM_PROCESS_KILL , e.g using mysql_kill()
This patch ensures that diagnostic area is initialized in this specific case.
If the setting of system variables does not allow to use join buffer
for a join query with GROUP BY <f1,...> / ORDER BY <f1,...> then
filesort is not needed if the first joined table is scanned in
the order compatible with order specified by the list <f1,...>.
Fix some problems in the TC_LOG_MMAP commit processing, which could
lead to assertions in some cases.
Problems are mostly reproducible in MariaDB 10.0 with asynchroneous
commit checkpoints, but most of the problems were present in earlier
versions also.
