Invaldating a subset of a sufficiently large query cache can take a long time.
During this time the server is efficiently frozen and no other operation can
be executed. This patch addresses this problem by moving the locks which cause
the freezing and also by temporarily disable the query cache while the
invalidation takes place.
The patch contains the following changes:
- Introduce auxilary functions to convenient work with character sets:
- resolve_charset();
- resolve_collation();
- get_default_db_collation();
- Introduce lex_string_set();
- Refactor Table_trigger_list::process_triggers() &
sp_head::execute_trigger() to be consistent with other code;
- Move reusable code from add_table_for_trigger() into
build_trn_path(), check_trn_exists() and load_table_name_for_trigger()
to be used in the following patch.
- Rename triggers_file_ext and trigname_file_ext into TRN_EXT and
TRG_EXT respectively.
- A race condition caused brief unavailablility when trying to acccess
a table.
- The variable 'grant_option' was removed to resolve the race condition and
to simplify the design pattern. This flag was originally intended to optimize
grant checks.
The following type conversions was done:
- Changed byte to uchar
- Changed gptr to uchar*
- Change my_string to char *
- Change my_size_t to size_t
- Change size_s to size_t
Removed declaration of byte, gptr, my_string, my_size_t and size_s.
Following function parameter changes was done:
- All string functions in mysys/strings was changed to use size_t
instead of uint for string lengths.
- All read()/write() functions changed to use size_t (including vio).
- All protocoll functions changed to use size_t instead of uint
- Functions that used a pointer to a string length was changed to use size_t*
- Changed malloc(), free() and related functions from using gptr to use void *
as this requires fewer casts in the code and is more in line with how the
standard functions work.
- Added extra length argument to dirname_part() to return the length of the
created string.
- Changed (at least) following functions to take uchar* as argument:
- db_dump()
- my_net_write()
- net_write_command()
- net_store_data()
- DBUG_DUMP()
- decimal2bin() & bin2decimal()
- Changed my_compress() and my_uncompress() to use size_t. Changed one
argument to my_uncompress() from a pointer to a value as we only return
one value (makes function easier to use).
- Changed type of 'pack_data' argument to packfrm() to avoid casts.
- Changed in readfrm() and writefrom(), ha_discover and handler::discover()
the type for argument 'frmdata' to uchar** to avoid casts.
- Changed most Field functions to use uchar* instead of char* (reduced a lot of
casts).
- Changed field->val_xxx(xxx, new_ptr) to take const pointers.
Other changes:
- Removed a lot of not needed casts
- Added a few new cast required by other changes
- Added some cast to my_multi_malloc() arguments for safety (as string lengths
needs to be uint, not size_t).
- Fixed all calls to hash-get-key functions to use size_t*. (Needed to be done
explicitely as this conflict was often hided by casting the function to
hash_get_key).
- Changed some buffers to memory regions to uchar* to avoid casts.
- Changed some string lengths from uint to size_t.
- Changed field->ptr to be uchar* instead of char*. This allowed us to
get rid of a lot of casts.
- Some changes from true -> TRUE, false -> FALSE, unsigned char -> uchar
- Include zlib.h in some files as we needed declaration of crc32()
- Changed MY_FILE_ERROR to be (size_t) -1.
- Changed many variables to hold the result of my_read() / my_write() to be
size_t. This was needed to properly detect errors (which are
returned as (size_t) -1).
- Removed some very old VMS code
- Changed packfrm()/unpackfrm() to not be depending on uint size
(portability fix)
- Removed windows specific code to restore cursor position as this
causes slowdown on windows and we should not mix read() and pread()
calls anyway as this is not thread safe. Updated function comment to
reflect this. Changed function that depended on original behavior of
my_pwrite() to itself restore the cursor position (one such case).
- Added some missing checking of return value of malloc().
- Changed definition of MOD_PAD_CHAR_TO_FULL_LENGTH to avoid 'long' overflow.
- Changed type of table_def::m_size from my_size_t to ulong to reflect that
m_size is the number of elements in the array, not a string/memory
length.
- Moved THD::max_row_length() to table.cc (as it's not depending on THD).
Inlined max_row_length_blob() into this function.
- More function comments
- Fixed some compiler warnings when compiled without partitions.
- Removed setting of LEX_STRING() arguments in declaration (portability fix).
- Some trivial indentation/variable name changes.
- Some trivial code simplifications:
- Replaced some calls to alloc_root + memcpy to use
strmake_root()/strdup_root().
- Changed some calls from memdup() to strmake() (Safety fix)
- Simpler loops in client-simple.c
when there are no up-to-date system tables to support it:
- initialize the scheduler before reporting "Ready for connections".
This ensures that warnings, if any, are printed before "Ready for
connections", and this message is not mangled.
- do not abort the scheduler if there are no system tables
- check the tables once at start up, remember the status and disable
the scheduler if the tables are not up to date.
If one attempts to use the scheduler with bad tables,
issue an error message.
- clean up the behaviour of the module under LOCK TABLES and pre-locking
mode
- make sure implicit commit of Events DDL works as expected.
- add more tests
Collateral clean ups in the events code.
This patch fixes Bug#23631 Events: SHOW VARIABLES doesn't work
when mysql.event is damaged
The problem was that THD::db_access variable was not restored after
database switch in stored-routine-execution code.
The fix is to restore THD::db_access in this case.
Unfortunately, this fix requires additional changes,
because in prepare_schema_table(), called on the parsing stage, we checked
privileges. That was wrong according to our design, but this flaw haven't
struck so far, because it was masked. All privilege checkings must be
done on the execution stage in order to be compatible with prepared statements
and stored routines. So, this patch also contains patch for
prepare_schema_table(), which moves the checkings to the execution phase.
execution breaks replication.
When a stored routine is executed, we switch current
database to the database, in which the routine
has been created. When the stored routine finishes,
we switch back to the original database.
The problem was that if the original database does not
exist (anymore) after routine execution, we raised an error.
The fix is to report a warning, and switch to the NULL database.
Fixed compiler warnings (detected by VC++):
- Removed not used variables
- Added casts
- Fixed wrong assignments to bool
- Fixed wrong calls with bool arguments
- Added missing argument to store(longlong), which caused wrong store method to be called.
- Removed not used variables
- Changed some ulong parameters/variables to ulonglong (possible serious bug)
- Added casts to get rid of safe assignment from longlong to long (and similar)
- Added casts to function parameters
- Fixed signed/unsigned compares
- Added some constructores to structures
- Removed some not portable constructs
Better fix for bug Bug #21428 "skipped 9 bytes from file: socket (3)" on "mysqladmin shutdown"
(Added new parameter to net_clear() to define when we want the communication buffer to be emptied)
(race cond)
It was possible for one thread to interrupt a Data Definition Language
statement and thereby get messages to the binlog out of order. Consider:
Connection 1: Drop Foo x
Connection 2: Create or replace Foo x
Connection 2: Log "Create or replace Foo x"
Connection 1: Log "Drop Foo x"
Local end would have Foo x, but the replicated slaves would not.
The fix for this is to wrap all DDL and logging of a kind in the same mutex.
Since we already use mutexes for the various parts of altering the server,
this only entails moving the logging events down close to the action, inside
the mutex protection.
Continued implementation of WL#1324 (table name to filename encoding)
The intermediate (not temporary) files of the new table
during ALTER TABLE was visible for SHOW TABLES. These
intermediate files are copies of the original table with
the changes done by ALTER TABLE. After all the data is
copied over from the original table, these files are renamed
to the original tables file names. So they are not temporary
files. They persist after ALTER TABLE, but just with another
name.
In 5.0 the intermediate files are invisible for SHOW TABLES
because all file names beginning with "#sql" were suppressed.
This failed since 5.1.6 because even temporary table names were
converted when making file names from them. The prefix became
converted to "@0023sql". Converting the prefix during SHOW TABLES
would suppress the listing of user tables that start with "#sql".
The solution of the problem is to continue the implementation of
the table name to file name conversion feature. One requirement
is to suppress the conversion for temporary table names.
This change is straightforward for real temporary tables as there
is a function that creates temporary file names.
But the generated path names are located in TMPDIR and have no
relation to the internal table name. This cannot be used for
ALTER TABLE. Its intermediate files need to be in the same
directory as the old table files. And it is necessary to be
able to deduce the same path from the same table name repeatedly.
Consequently the intermediate table files must be handled like normal
tables. Their internal names shall start with tmp_file_prefix
(#sql) and they shall not be converted like normal table names.
I added a flags parameter to all relevant functions that are
called from ALTER TABLE. It is used to suppress the conversion
for the intermediate table files.
The outcome is that the suppression of #sql in SHOW TABLES
works again. It does not suppress user tables as these are
converted to @0023sql on file level.
This patch does also fix ALTER TABLE ... RENAME, which could not
rename a table with non-ASCII characters in its name.
It does also fix the problem that a user could create a table like
`#sql-xxxx-yyyy`, where xxxx is mysqld's pid and yyyy is the thread
ID of some other thread, which prevented this thread from running
ALTER TABLE.
Some of the above problems are mentioned in Bug 1405, which can
be closed with this patch.
This patch does also contain some minor fixes for other forgotten
conversions. Still known problems are reported as bugs 21370,
21373, and 21387.
Fix for BUG#16676: Database CHARSET not used for stored procedures
The problem in BUG#16211 is that CHARSET-clause of the return type for
stored functions is just ignored.
The problem in BUG#16676 is that if character set is not explicitly
specified for sp-variable, the server character set is used instead
of the database one.
The fix has two parts:
- always store CHARSET-clause of the return type along with the
type definition in mysql.proc.returns column. "Always" means that
CHARSET-clause is appended even if it has not been explicitly
specified in CREATE FUNCTION statement (this affects BUG#16211 only).
Storing CHARSET-clause if it is not specified is essential to avoid
changing character set if the database character set is altered in
the future.
NOTE: this change is not backward compatible with the previous releases.
- use database default character set if CHARSET-clause is not explicitly
specified (this affects both BUG#16211 and BUG#16676).
NOTE: this also breaks backward compatibility.
No test case as the bug is in an existing test case (rpl_trigger.test
when it is run under valgrind).
The warning was caused by memory corruption in replication slave: thd->db
was pointing at a stack address that was previously used by
sp_head::execute()::old_db. This happened because mysql_change_db
behaved differently in replication slave and did not make a copy of the
argument to assign to thd->db.
The solution is to always free the old value of thd->db and allocate a new
copy, regardless whether we're running in a replication slave or not.
5th cut, moved DB related code to Event_db_repository and
updated accordingly the remanining code.
Moved change/restore_security_context() to class THD
Removed events_priv.h
Next step is to reorganize create/update_event() and parsing for them.
But probably some other refactoring could be done in the meanwhile.
The changes so far pass the test suite.
Bug#19022 "Memory bug when switching db during trigger execution"
Bug#17199 "Problem when view calls function from another database."
Bug#18444 "Fully qualified stored function names don't work correctly in
SELECT statements"
Documentation note: this patch introduces a change in behaviour of prepared
statements.
This patch adds a few new invariants with regard to how THD::db should
be used. These invariants should be preserved in future:
- one should never refer to THD::db by pointer and always make a deep copy
(strmake, strdup)
- one should never compare two databases by pointer, but use strncmp or
my_strncasecmp
- TABLE_LIST object table->db should be always initialized in the parser or
by creator of the object.
For prepared statements it means that if the current database is changed
after a statement is prepared, the database that was current at prepare
remains active. This also means that you can not prepare a statement that
implicitly refers to the current database if the latter is not set.
This is not documented, and therefore needs documentation. This is NOT a
change in behavior for almost all SQL statements except:
- ALTER TABLE t1 RENAME t2
- OPTIMIZE TABLE t1
- ANALYZE TABLE t1
- TRUNCATE TABLE t1 --
until this patch t1 or t2 could be evaluated at the first execution of
prepared statement.
CURRENT_DATABASE() still works OK and is evaluated at every execution
of prepared statement.
Note, that in stored routines this is not an issue as the default
database is the database of the stored procedure and "use" statement
is prohibited in stored routines.
This patch makes obsolete the use of check_db_used (it was never used in the
old code too) and all other places that check for table->db and assign it
from THD::db if it's NULL, except the parser.
How this patch was created: THD::{db,db_length} were replaced with a
LEX_STRING, THD::db. All the places that refer to THD::{db,db_length} were
manually checked and:
- if the place uses thd->db by pointer, it was fixed to make a deep copy
- if a place compared two db pointers, it was fixed to compare them by value
(via strcmp/my_strcasecmp, whatever was approproate)
Then this intermediate patch was used to write a smaller patch that does the
same thing but without a rename.
TODO in 5.1:
- remove check_db_used
- deploy THD::set_db in mysql_change_db
See also comments to individual files.
Unify method naming -> create/update/drop_event
Move class Event_timed to event_timed.h
class Events is in events.h (renamed from event.h)
The implementation is in events.cc (renamed from event.h)
The order of acquiring LOCK_mysql_create_db
and wait_if_global_read_lock() was wrong. It could happen
that a thread held LOCK_mysql_create_db while waiting for
the global read lock to be released. The thread with the
global read lock could try to administrate a database too.
It would first try to lock LOCK_mysql_create_db and hang...
The check if the current thread has the global read lock
is done in wait_if_global_read_lock(), which could not be
reached because of the hang in LOCK_mysql_create_db.
Now I exchanged the order of acquiring LOCK_mysql_create_db
and wait_if_global_read_lock(). This makes
wait_if_global_read_lock() fail with an error message for
the thread with the global read lock. No deadlock happens.
- Scheduler is either initialized at server start or never.
Starting & stopping is now suspending & resuming.
- The scheduler has clear OO interface
- Now all calls to the scheduler are synchronous
- GLOBAL event_scheduler uses thd::sys_var_tmp (see set_var.cc)
- External API is encapsulated into class Events
- Includes fixes for all comments of Kostja's review of 19.05.2005
Starting to merge into 5.1-release (5.1.10) and push
Problem:
Renaming a database to itself crashed server.
It hapenned because of wrong DBUG_ASSERT.
Fix: removing wrong DBUG_ASSERT. Now it reports
a correct error message "database alreadt exists".
