Description: When querying a subset of columns from the information_schema.TABLES
Analysis: When information about tables is collected for statements like
"SELECT ENGINE FROM I_S.TABLES" we do not perform full-blown table opens
in SE, instead we only use information from table shares from the Table
Definition Cache or .FRMs. Still in order to simplify I_S implementation
mock TABLE objects are created from TABLE_SHARE during this process.
This is done by calling open_table_from_share() function with special
arguments. Since this function always increments "Opened_tables" counter,
calls to it can be mistakingly interpreted as full-blown table opens in SE.
Note that claim that "'SELECT ENGINE FROM I_S.TABLES' statement doesn't
use Table Cache" is nevertheless factually correct. But it misses the
point, since such statements a) don't use full-blown TABLE objects and
therefore don't do table opens b) still use Table Definition Cache.
Fix: We are now incrementing the counter when db_stat(i.e open flags for ha_open(
we have considered an optimization which would use TABLE objects from
Table Cache when available instead of constructing mock TABLE objects,
but found it too intrusive for stable releases.
main.information_schema: added a condition to the query to exclude perfschema tables
main.information_schema_all_engines: added a call to the include file to check for the presence of perfschema
Add missing REAP to the test.
A later test failed with strange incorrect values for COM_SELECT
in information_schema.global_status. Since global_status is updated
at the end of session activity, it seems appropriate to ensure that
all background connections have completed before accessing it.
(I checked that the original bug still triggers the test case after
the modification with REAP).
Merge from mysql-5.6:
revno: 3257
committer: Jon Olav Hauglid <jon.hauglid@oracle.com>
branch nick: mysql-trunk-bug11756966
timestamp: Thu 2011-07-14 09:32:01 +0200
message:
Bug#11756966 - 48958: STORED PROCEDURES CAN BE LEVERAGED TO BYPASS
DATABASE SECURITY
The problem was that CREATE PROCEDURE/FUCTION could be used to
check the existence of databases for which the user had no
privileges and therefore should not be allowed to see.
The reason was that existence of a given database was checked
before privileges. So trying to create a stored routine in
a non-existent database would give a different error than trying
to create a stored routine in a restricted database.
This patch fixes the problem by changing the order of the checks
for CREATE PROCEDURE/FUNCTION so that privileges are checked first.
This means that trying to create a stored routine in a
non-existent database and in a restricted database both will
give ER_DBACCESS_DENIED_ERROR error.
Test case added to grant.test.
- Make do_fill_table() use join_tab->cache_select->cond if it is present. When
join_tab->cache_select->cond is present, join_tab->select_cond doesn't have any
conditions that are usable for I_S optimizations.
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.
storage/innobase/handler/handler0alter.cc:
for NEWDATE key_type says unsigned, thus col->prtype says unsigned,
but field->flags says signed. Use the same flag for value retrieval
that was used for value storage.
FOR CERTAIN QUERIES TO INFORMATION_SCHEMA".
The problem was that metadata locking subsystem introduced
too much overhead for queries to I_S which were processed by
opening only .FRM or .TRG files and had to scanned a lot of
tables (e.g. SELECT COUNT(*) FROM I_S.TRIGGERS was affected).
The same effect was not observed for similar queries which
performed full-blown table open in order to fill I_S table.
The problem stemmed from the fact that in case when I_S
implementation opened only .FRM or .TRG file for each table
processed it didn't release metadata lock it has acquired on
the table after finishing its processing. As result, list
of acquired metadata locks were growing until the end of
statement. Since acquisition of each new lock required
search in the list of already acquired locks performance
degraded.
The same effect is not observed when I_S implementation
performs full-blown table open for each table being
processed, as in the latter cases metadata lock on the
table is released right after table processing.
This fix addressed the problem by ensuring that I_S
implementation releases metadata lock after processing
the table in both cases of full-blown table open and in
case when only .FRM or .TRG file is read.
mysql-test/r/information_schema.result:
Added coverage for bug #12828477 - "MDL SUBSYSTEM CREATES BIG
OVERHEAD FOR CERTAIN QUERIES TO INFORMATION_SCHEMA".
mysql-test/t/information_schema.test:
Added coverage for bug #12828477 - "MDL SUBSYSTEM CREATES BIG
OVERHEAD FOR CERTAIN QUERIES TO INFORMATION_SCHEMA".
sql/sql_show.cc:
Changed fill_schema_table_from_frm() to release metadata lock
it has acquired after processing the .FRM or .TRG file for
table.
Without this step metadata locks acquired for each table
processed will be accumulated. In situation when a lot of
tables are processed by I_S query this will result in
transaction with too many metadata locks. As result
performance of acquisition of new lock will degrade.
FOR CERTAIN QUERIES TO INFORMATION_SCHEMA".
The problem was that metadata locking subsystem introduced
too much overhead for queries to I_S which were processed by
opening only .FRM or .TRG files and had to scanned a lot of
tables (e.g. SELECT COUNT(*) FROM I_S.TRIGGERS was affected).
The same effect was not observed for similar queries which
performed full-blown table open in order to fill I_S table.
The problem stemmed from the fact that in case when I_S
implementation opened only .FRM or .TRG file for each table
processed it didn't release metadata lock it has acquired on
the table after finishing its processing. As result, list
of acquired metadata locks were growing until the end of
statement. Since acquisition of each new lock required
search in the list of already acquired locks performance
degraded.
The same effect is not observed when I_S implementation
performs full-blown table open for each table being
processed, as in the latter cases metadata lock on the
table is released right after table processing.
This fix addressed the problem by ensuring that I_S
implementation releases metadata lock after processing
the table in both cases of full-blown table open and in
case when only .FRM or .TRG file is read.
sql_show.cc during rqg_info_schema test on Windows".
Ensure we do not access freed memory when filling
information_schema.views when one of the views
could not be properly opened.
mysql-test/r/information_schema.result:
Update results - a fix for Bug#56540.
mysql-test/t/information_schema.test:
Add a test case for Bug#56540
sql/sql_base.cc:
Push an error into the Diagnostics area
when we return an error.
This directs get_all_tables() to the execution
branch which doesn't involve 'process_table()'
when no table/view was opened.
sql/sql_show.cc:
Do not try to access underlying table fields
when opening of a view failed. The underlying
table is closed in that case, and accessing
its fields may lead to dereferencing a damaged
pointer.
sql_show.cc during rqg_info_schema test on Windows".
Ensure we do not access freed memory when filling
information_schema.views when one of the views
could not be properly opened.
- Changed to still use bcmp() in certain cases becasue
- Faster for short unaligneed strings than memcmp()
- Bettern when using valgrind
- Changed to use my_sprintf() instead of sprintf() to get higher portability for old systems
- Changed code to use MariaDB version of select->skip_record()
- Removed -%::SCCS/s.% from Makefile.am:s to remove automake warnings
FLUSH TABLES <list> WITH READ LOCK are incompatible" to
be pushed as separate patch.
Replaced thread state name "Waiting for table", which was
used by threads waiting for a metadata lock or table flush,
with a set of names which better reflect types of resources
being waited for.
Also replaced "Table lock" thread state name, which was used
by threads waiting on thr_lock.c table level lock, with more
elaborate "Waiting for table level lock", to make it
more consistent with other thread state names.
Updated test cases and their results according to these
changes.
Fixed sys_vars.query_cache_wlock_invalidate_func test to not
to wait for timeout of wait_condition.inc script.
mysql-test/r/query_cache.result:
Added test coverage for query_cache_wlock_invalidate
behavior for implicitly locked tables.
mysql-test/suite/sys_vars/r/query_cache_wlock_invalidate_func.result:
Fixed sys_vars.query_cache_wlock_invalidate_func test to not
to wait for timeout of wait_condition.inc script. Reverted
changes to test which introduced timeout and replaced waiting
condition with a more appropriate one.
Test coverage for query_cache_wlock_invalidate behavior for
implicitly locked tables was added to query_cache.test.
mysql-test/suite/sys_vars/t/query_cache_wlock_invalidate_func.test:
Fixed sys_vars.query_cache_wlock_invalidate_func test to not
to wait for timeout of wait_condition.inc script. Reverted
changes to test which introduced timeout and replaced waiting
condition with a more appropriate one.
Test coverage for query_cache_wlock_invalidate behavior for
implicitly locked tables was added to query_cache.test.
mysql-test/t/query_cache.test:
Added test coverage for query_cache_wlock_invalidate
behavior for implicitly locked tables.
mysys/thr_lock.c:
Replaced "Table lock" thread state name, which was used by
threads waiting on thr_lock.c table level lock, with more
elaborate "Waiting for table level lock", to make it
consistent with thread state names which are used while
waiting for metadata locks and table flush.
sql/mdl.cc:
Replaced thread state name "Waiting for table", which was
used by threads waiting for a metadata lock or table flush,
with a set of names which better reflect types of resources
being waited for.
To implement this:
- Adjusted MDL_wait::timed_wait() to take thread state name
as parameter.
- Introduced method of MDL_key class which allows to get
thread state name to be used while waiting for resource
corresponding to the key and changed code to use it.
Added array translating namespaces to thread state names
as part of this change.
sql/mdl.h:
To implement this:
- Adjusted MDL_wait::timed_wait() to take thread state name
as parameter.
- Introduced method of MDL_key class which allows to get
thread state name to be used while waiting for resource
corresponding to the key and changed code to use it.
Added array translating namespaces to thread state names
as part of this change.
sql/sql_base.cc:
Replaced thread state name "Waiting for table", which was
used by threads waiting for table flush, with a more elaborate
"Waiting for table flush".
FLUSH TABLES <list> WITH READ LOCK are incompatible" to
be pushed as separate patch.
Replaced thread state name "Waiting for table", which was
used by threads waiting for a metadata lock or table flush,
with a set of names which better reflect types of resources
being waited for.
Also replaced "Table lock" thread state name, which was used
by threads waiting on thr_lock.c table level lock, with more
elaborate "Waiting for table level lock", to make it
more consistent with other thread state names.
Updated test cases and their results according to these
changes.
Fixed sys_vars.query_cache_wlock_invalidate_func test to not
to wait for timeout of wait_condition.inc script.
During creation of the table list of
processed tables hidden I_S table 'VARIABLES'
is erroneously added into the table list.
it leads to ER_UNKNOWN_TABLE error in
TABLE_LIST::add_table_to_list() function.
The fix is to skip addition of hidden I_S
tables into the table list.
mysql-test/r/information_schema.result:
test case
mysql-test/t/information_schema.test:
test case
sql/sql_show.cc:
The fix is to skip addition of hidden I_S
tables into the table list.
During creation of the table list of
processed tables hidden I_S table 'VARIABLES'
is erroneously added into the table list.
it leads to ER_UNKNOWN_TABLE error in
TABLE_LIST::add_table_to_list() function.
The fix is to skip addition of hidden I_S
tables into the table list.
* fully support --mysqld=--plugin-load=xxxx
* uniformly support all loadable plugins, no need to hard-code
every new plugin in mtr
* autodetect MTR_VS_CONFIG on windows
- Adjust timing in test case, to avoid test failures caused by high load
on machines and consequent race conditions in the test case.
- Add another variant of Valgrind suppressions for memory leak in system
libraries when unloading dynamic object files.
mysql-test/r/information_schema.result:
Adjust timing to avoid test failures due to races.
mysql-test/t/information_schema.test:
Adjust timing to avoid test failures due to races.
mysql-test/valgrind.supp:
Add another variant of valgrind suppression for leak in system libs.
