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.
Addendum fixes after changing the condition variable
for the global read lock.
The stress test suite revealed some deadlocks. Some were
related to the new condition variable (COND_global_read_lock)
and some were general problems with the global read lock.
It is now necessary to signal COND_global_read_lock whenever
COND_refresh is signalled.
We need to wait for the release of a global read lock if one
is set before every operation that requires a write lock.
But we must not wait if we have locked tables by LOCK TABLES.
After setting a global read lock a thread waits until all
write locks are released.
INSERT triggers".
In cases when REPLACE was internally executed via update and table had
on update (on delete) triggers defined we exposed the fact that such
optimization used by callng on update (not calling on delete) triggers.
Such behavior contradicts our documentation which describes REPLACE as
INSERT with optional DELETE.
This fix just disables this optimization for tables with on delete triggers.
The optimization is still applied for tables which have on update but have
no on delete triggers, we just don't invoke on update triggers in this case
and thus don't expose information about optimization to user.
Also added test coverage for values returned by ROW_COUNT() function (and
thus for values returned by mysql_affected_rows()) for various forms of
INSERT.
The INSERT DELAYED should not maintain its own private auto-increment
counter, because this is assuming that other threads cannot insert
into the table while the INSERT DELAYED thread is inserting, which is
a wrong assumption.
So the start of processing of a batch of INSERT rows in the
INSERT DELAYED thread must be treated as a start of a new statement
and cached next_insert_id must be cleared.
The check for view security was lacking several points :
1. Check with the right set of permissions : for each table ref that
participates in a view there were the right credentials to use in it's
security_ctx member, but these weren't used for checking the credentials.
This makes hard enforcing the SQL SECURITY DEFINER|INVOKER property
consistently.
2. Because of the above the security checking for views was just ruled out
in explicit ways in several places.
3. The security was checked only for the columns of the tables that are
brought into the query from a view. So if there is no column reference
outside of the view definition it was not detecting the lack of access to
the tables in the view in SQL SECURITY INVOKER mode.
The fix below tries to fix the above 3 points.
or implicitly uses stored function gives "Table not locked" error'
CREATE TABLE ... SELECT ... statement which was explicitly or implicitly
(through view) using stored function gave "Table not locked" error.
The actual bug resides in the current locking scheme of CREATE TABLE SELECT
code, which first opens and locks tables of the SELECT statement itself,
and then, having SELECT tables locked, creates the .FRM, opens the .FRM and
acquires lock on it. This scheme opens a possibility for a deadlock, which
was present and ignored since version 3.23 or earlier. This scheme also
conflicts with the invariant of the prelocking algorithm -- no table can
be open and locked while there are tables locked in prelocked mode.
The patch makes an exception for this invariant when doing CREATE TABLE ...
SELECT, thus extending the possibility of a deadlock to the prelocked mode.
We can't supply a better fix in 5.0.
Additional fix for INSERT DELAYED with subselect.
Originally detected in 5.1, but 5.0 could also be affected.
The user thread creates a dummy table object,
which is not included in the lock. The 'real' table is
opened and locked by the 'delayed' system thread.
The dummy object is now marked as not locked and this is
tested in mysql_lock_have_duplicate().
The bug was caused by wrong behaviour of mysql_insert() which in case
of INSERT DELAYED into a view exited with thd->net.report_error == 0.
This blocked error reporting to the client which started waiting
infinitely for response to the query.
A table with an on insert trigger was reported as crashed when the insert
was processed with bulk insert mode on (handler::start_bulk_insert).
The trigger was also selecting from the same table, and that caused
the "crash".
The same problem was present when an insert statement, which was processed
in bulk mode, also used a stored function that was reading the same table.
This fix disables bulk inserts if a statement uses functions or invokes
triggers. Implementing more granular checks will require much more code and
therefore can hardly be done in 5.0
- Fixed tests
- Optimized new code
- Fixed some unlikely core dumps
- Better bug fixes for:
- #14397 - OPTIMIZE TABLE with an open HANDLER causes a crash
- #14850 (ERROR 1062 when a quering a view using a Group By on a column that can be null
Problem #1: INSERT...SELECT, Version for 5.0.
Extended the unique table check by a check of lock data.
Merge sub-tables cannot be detected by doing name checks only.
- CHAR() now returns binary string as default
- CHAR(X*65536+Y*256+Z) is now equal to CHAR(X,Y,Z) independent of the character set for CHAR()
- Test for both ETIMEDOUT and ETIME from pthread_cond_timedwait()
(Some old systems returns ETIME and it's safer to test for both values
than to try to write a wrapper for each old system)
- Fixed new introduced bug in NOT BETWEEN X and X
- Ensure we call commit_by_xid or rollback_by_xid for all engines, even if one engine has failed
- Use octet2hex() for all conversion of string to hex
- Simplify and optimize code
This bug occurs when some trigger for table used by DML statement is created
or changed while statement was waiting in lock_tables(). In this situation
prelocking set which we have calculated becames invalid which can easily lead
to errors and even in some cases to crashes.
With proposed patch we no longer silently reopen tables in lock_tables(),
instead caller of lock_tables() becomes responsible for reopening tables and
recalculation of prelocking set.
"Process NATURAL and USING joins according to SQL:2003".
* Some of the main problems fixed by the patch:
- in "select *" queries the * expanded correctly according to
ANSI for arbitrary natural/using joins
- natural/using joins are correctly transformed into JOIN ... ON
for any number/nesting of the joins.
- column references are correctly resolved against natural joins
of any nesting and combined with arbitrary other joins.
* This patch also contains a fix for name resolution of items
inside the ON condition of JOIN ... ON - in this case items must
be resolved only against the JOIN operands. To support such
'local' name resolution, the patch introduces a stack of
name resolution contexts used at parse time.
NOTICE:
- This patch is not complete in the sense that
- there are 2 test cases that still do not pass -
one in join.test, one in select.test. Both are marked
with a comment "TODO: WL#2486".
- it does not include a new test specific for the task
ETIME was returned by cond_timedwait (sic, the pre-POSIX1001b function) on
Solaris 2.6 and 2.7. pthread_cond_timedwait on Solaris returns ETIMEDOUT.
The standard requirement is that the only additional return value
of pthred_cond_timedwait compared to pthread_cond_wait is ETIMEDOUT.
Let us not bloat the application code with redundant checks,
and if we're ever to work on a platform that returns a non-standard
value, we should write a wrapper for that platform (like we do, e.g., for
Windows).
