When executing drop view statement on the master, the statement is not written into bin-log if any error occurs, this could cause master slave inconsistence if any view has been dropped.
If some error occured and no view has been dropped, don't bin-log the statement, if at least one view has been dropped the query is bin-logged possible with an error.
When executing drop view statement on the master, the statement is written
into bin-log without checking for possible errors, so the statement would
always be bin-logged with error code cleared even if some error might occur,
for example, some of the views being dropped does not exist. This would cause
failure on the slave.
Writing bin-log after check for errors, if at least one view has been dropped
the query is bin-logged possible with an error.
Non-definer of a view was allowed to alter that view. Due to this the alterer
can elevate his access rights to access rights of the view definer and thus
modify data which he wasn't allowed to modify. A view defined with
SQL SECURITY INVOKER can't be used directly for access rights elevation.
But a user can first alter the view SQL code and then alter the view to
SQL SECURITY DEFINER and thus elevate his access rights. Due to this
altering a view with SQL SECURITY INVOKER is also prohibited.
Now the mysql_create_view function allows ALTER VIEW only to the view
definer or a super user.
causes full table lock on innodb table.
Also fixes Bug#28502 Triggers that update another innodb table
will block on X lock unnecessarily (duplciate).
Code review fixes.
Both bugs' synopses are misleading: InnoDB table is
not X locked. The statements, however, cannot proceed concurrently,
but this happens due to lock conflicts for tables used in triggers,
not for the InnoDB table.
If a user had an InnoDB table, and two triggers, AFTER UPDATE and
AFTER INSERT, competing for different resources (e.g. two distinct
MyISAM tables), then these two triggers would not be able to execute
concurrently. Moreover, INSERTS/UPDATES of the InnoDB table would
not be able to run concurrently.
The problem had other side-effects (see respective bug reports).
This behavior was a consequence of a shortcoming of the pre-locking
algorithm, which would not distinguish between different DML operations
(e.g. INSERT and DELETE) and pre-lock all the tables
that are used by any trigger defined on the subject table.
The idea of the fix is to extend the pre-locking algorithm to keep track,
for each table, what DML operation it is used for and not
load triggers that are known to never be fired.
- BUG#11986: Stored routines and triggers can fail if the code
has a non-ascii symbol
- BUG#16291: mysqldump corrupts string-constants with non-ascii-chars
- BUG#19443: INFORMATION_SCHEMA does not support charsets properly
- BUG#21249: Character set of SP-var can be ignored
- BUG#25212: Character set of string constant is ignored (stored routines)
- BUG#25221: Character set of string constant is ignored (triggers)
There were a few general problems that caused these bugs:
1. Character set information of the original (definition) query for views,
triggers, stored routines and events was lost.
2. mysqldump output query in client character set, which can be
inappropriate to encode definition-query.
3. INFORMATION_SCHEMA used strings with mixed encodings to display object
definition;
1. No query-definition-character set.
In order to compile query into execution code, some extra data (such as
environment variables or the database character set) is used. The problem
here was that this context was not preserved. So, on the next load it can
differ from the original one, thus the result will be different.
The context contains the following data:
- client character set;
- connection collation (character set and collation);
- collation of the owner database;
The fix is to store this context and use it each time we parse (compile)
and execute the object (stored routine, trigger, ...).
2. Wrong mysqldump-output.
The original query can contain several encodings (by means of character set
introducers). The problem here was that we tried to convert original query
to the mysqldump-client character set.
Moreover, we stored queries in different character sets for different
objects (views, for one, used UTF8, triggers used original character set).
The solution is
- to store definition queries in the original character set;
- to change SHOW CREATE statement to output definition query in the
binary character set (i.e. without any conversion);
- introduce SHOW CREATE TRIGGER statement;
- to dump special statements to switch the context to the original one
before dumping and restore it afterwards.
Note, in order to preserve the database collation at the creation time,
additional ALTER DATABASE might be used (to temporary switch the database
collation back to the original value). In this case, ALTER DATABASE
privilege will be required. This is a backward-incompatible change.
3. INFORMATION_SCHEMA showed non-UTF8 strings
The fix is to generate UTF8-query during the parsing, store it in the object
and show it in the INFORMATION_SCHEMA.
Basically, the idea is to create a copy of the original query convert it to
UTF8. Character set introducers are removed and all text literals are
converted to UTF8.
This UTF8 query is intended to provide user-readable output. It must not be
used to recreate the object. Specialized SHOW CREATE statements should be
used for this.
The reason for this limitation is the following: the original query can
contain symbols from several character sets (by means of character set
introducers).
Example:
- original query:
CREATE VIEW v1 AS SELECT _cp1251 'Hello' AS c1;
- UTF8 query (for INFORMATION_SCHEMA):
CREATE VIEW v1 AS SELECT 'Hello' AS c1;
ALTER VIEW is currently not supported as a prepared statement
and should be disabled as such as they otherwise could cause server crashes.
ALTER VIEW is currently not supported when called from stored
procedures or functions for related reasons and should also be disabled.
This patch disables these DDL statements and adjusts the appropriate test
cases accordingly.
Additional tests has been added to reflect on the fact that we do support
CREATE/ALTER/DROP TABLE for Prepared Statements (PS), Stored Procedures (SP)
and PS within SP.
CREATE/DROP TEMPORARY TABLE + ROLLBACK on master
The transaction ability of the storage engines of
the tables on the replication master and the replication
slave must generally be the same.
When the storage engine type of the slave is
non-transactional then transactions on the master that
mix update of transactional and non-transactional tables
should be avoided because they will cause inconsistency of
the data between the master's transactional table and the
slave's non-transactional table.
The effect described by this bug is actually expected.
A detailed test case is added (to be merged later to
the updated rpl_ddl.test), as there was no coverage
by the existing tests.
Some code cleanup is also added by this change.
1. Introduce parse_sql() as a high-level replacement for MYSQLparse().
parse_sql() is responsible to switch and restore "parser context"
(THD::m_lip for now).
2. Fix typo in sp.cc: THD::spcont should be reset *before* calling
the parser.
Bug 28127 (Some valid identifiers names are not parsed correctly)
Bug 26302 (MySQL server cuts off trailing "*/" from comments in SP/func)
This patch is the second part of a major cleanup, required to fix
Bug 25411 (trigger code truncated).
The root cause of the issue stems from the function skip_rear_comments,
which was a work around to remove "extra" "*/" characters from the query
text, when parsing a query and reusing the text fragments to represent a
view, trigger, function or stored procedure.
The reason for this work around is that "special comments",
like /*!50002 XXX */, were not parsed properly, so that a query like:
AAA /*!50002 BBB */ CCC
would be seen by the parser as "AAA BBB */ CCC" when the current version
is greater or equal to 5.0.2
The root cause of this stems from how special comments are parsed.
Special comments are really out-of-bound text that appear inside a query,
that affects how the parser behave.
In nature, /*!50002 XXX */ in MySQL is similar to the C concept
of preprocessing :
#if VERSION >= 50002
XXX
#endif
Depending on the current VERSION of the server, either the special comment
should be expanded or it should be ignored, but in all cases the "text" of
the query should be re-written to strip the "/*!50002" and "*/" markers,
which does not belong to the SQL language itself.
Prior to this fix, these markers would leak into :
- the storage format for VIEW,
- the storage format for FUNCTION,
- the storage format for FUNCTION parameters, in mysql.proc (param_list),
- the storage format for PROCEDURE,
- the storage format for PROCEDURE parameters, in mysql.proc (param_list),
- the storage format for TRIGGER,
- the binary log used for replication.
In all cases, not only this cause format corruption, but also provide a vector
for dormant security issues, by allowing to tunnel code that will be activated
after an upgrade.
The proper solution is to deal with special comments strictly during parsing,
when accepting a query from the outside world.
Once a query is parsed and an object is created with a persistant
representation, this object should not arbitrarily mutate after an upgrade.
In short, special comments are a useful but limited feature for MYSQLdump,
when used at an *interface* level to facilitate import/export,
but bloating the server *internal* storage format is *not* the proper way
to deal with configuration management of the user logic.
With this fix:
- the Lex_input_stream class now acts as a comment pre-processor,
and either expands or ignore special comments on the fly.
- MYSQLlex and sql_yacc.yy have been cleaned up to strictly use the
public interface of Lex_input_stream. In particular, how the input stream
accepts or rejects a character is private to Lex_input_stream, and the
internal buffer pointers of that class are strictly private, and should not
be tempered with during parsing.
This caused many changes mostly in sql_lex.cc.
During the code cleanup in case MY_LEX_NUMBER_IDENT,
Bug 28127 (Some valid identifiers names are not parsed correctly)
was found and fixed.
By parsing special comments properly, and removing the function
'skip_rear_comments' [sic],
Bug 26302 (MySQL server cuts off trailing "*/" from comments in SP/func)
has been fixed as well.
When the same VIEW was created at the master side twice,
malformed (truncated after the word 'AS') query string
was forwarded to client side, so error messages on the
master and client was different, and replication was
broken.
The mysql_register_view function call failed
too early: fields of `view' output argument of this
function was not filled yet with correct data required
for query replication.
The mysql_register_view function also copied pointers to
local buffers into a memory allocated by the caller.
- 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 root cause of this bug is related to the function skip_rear_comments,
in sql_lex.cc
Recent code changes in skip_rear_comments changed the prototype from
"const uchar*" to "const char*", which had an unforseen impact on this test:
(endp[-1] < ' ')
With unsigned characters, this code filters bytes of value [0x00 - 0x20]
With *signed* characters, this also filters bytes of value [0x80 - 0xFF].
This caused the regression reported, considering cyrillic characters in the
parameter name to be whitespace, and truncated.
Note that the regression is present both in 5.0 and 5.1.
With this fix:
- [0x80 - 0xFF] bytes are no longer considered whitespace.
This alone fixes the regression.
In addition, filtering [0x00 - 0x20] was found bogus and abusive,
so that the code now filters uses my_isspace when looking for whitespace.
Note that this fix is only addressing the regression affecting UTF-8
in general, but does not address a more fundamental problem with
skip_rear_comments: parsing a string *backwards*, starting at end[-1],
is not safe with multi-bytes characters, so that end[-1] can confuse the
last byte of a multi-byte characters with a characters to filter out.
The only known impact of this remaining issue affects objects that have to
meet all the conditions below:
- the object is a FUNCTION / PROCEDURE / TRIGGER / EVENT / VIEW
- the body consist of only *1* instruction, and does *not* contain a
BEGIN-END block
- the instruction ends, lexically, with <ident> <whitespace>* ';'?
For example, "select <ident>;" or "return <ident>;"
- The last character of <ident> is a multi-byte character
- the last byte of this character is ';' '*', '/' or whitespace
In this case, the body of the object will be truncated after parsing,
and stored in an invalid format.
This last issue has not been fixed in this patch, since the real fix
will be implemented by Bug 25411 (trigger code truncated), which is caused
by the very same code.
The real problem is that the function skip_rear_comments is only a
work-around, and should be removed entirely: see the proposed patch for
bug 25411 for details.
