Dump thread may encounter an error when reading events from the active binlog
file. However the errors may be temporary, so dump thread will try to read
the event again. But dump thread seeked to an wrong position, it caused some
events was sent twice.
To fix the bug, prev_pos is defined out the while loop and is set the correct
position after reading every event correctly.
This patch also make binlog_can_be_corrupted more accurate, only the binlogs
not closed normally are marked binlog_can_be_corrupted.
Finally, two warnings are added when dump threads encounter the temporary
errors.
NO ERRORS REPORTED
Problem:
=======
Errors from my_b_fill are ignored. MYSQL_BIN_LOG::write_cache
code assumes that 0 returned from my_b_fill always means
end-of-cache, but that is incorrect. It can result in error
and the error is ignored. Other callers of my_b_fill don't
check for error: my_b_copy_to_file, maybe my_b_gets.
Fix:
===
An error handler is already present to check the "cache"
error that is reported during "MYSQL_BIN_LOG::write_cache"
call. Hence error handlers are added for "my_b_copy_to_file"
and "my_b_gets".
During my_b_fill() function call, when the cache read fails
info->error= -1 is set. Hence a check for "info->error"
is added for the above to callers upon their return.
At logging a first Query referring a user var, the slave missed to log the user var.
It appears that at execution of a Uservar event the slaver applier
thought of the variable as already logged.
The reason of misjudgement is in coincidence of query id:s: of one that the thread
holds at Uservar execution and another one that the thread sees at the Query applying.
While the two are naturally different in the regular execution branch (as two computational
events are separated as individual events), in the deferred applying case the User var execution
effectively belongs to its Query processing.
Fixed with storing the Uservar parsing time (where desicion to defer is taken) query id
to temporarily substitute with it the actual query id at the Uservar execution time
(along with its query).
Such manipulation mimics behaviour of the regular applying branch.
In method mysql_binlog_send, right after detecting a EOF in the
read event loop, and before deciding if we should change to a new
binlog file there is a execution window where new events can be
written to the binlog and a rotation can happen. When reaching
the test, the function will then change to a new binlog file
ignoring all the events written in this window. This will result
in events not being replicated.
Only when the binlog is detected as deactivated in the event loop
of the dump thread, can we really know that no more events
remain. For this reason, this test is now made under the log lock
in the beginning of the event loop when reading the events.
On a previous fix, user variables with zero length name were incorrectly
considered as event corruption, despite that them are allowed by server.
Fix this wrong assumption by allowing again user variables with zero
length on binary log.
RATHER THAN A TABLE
Problem: In RBR, If a table is converted into a view at slave,
(i.e., "drop table 'object1'" & "create view 'object1'"), then any
DML operations on the table at master are causing crash at slave.
Analysis: Slave prepares tables to be opened for DML list when it
receives Table_map_log_event(s). And the same list will be sent to
open_table function. Open_table logic assumes that if the list
contains a view object, it also contains "select_lex" object of
that view. In the above special case, the table object does not
contain 'select_lex' as it is base table at master. Since it
is a view at slave, open_table logic goes to 'mysql_make_view()'
function which assumes that 'select_lex' exists for the object.
Fix: While preparing 'tables to be opened' list, we should make
sure that table required type is 'base table'. If it is not
base table while opening the object, mysql_make_view will throw an
error similar to 'object is not a base table'
FORMAT_DESCRIPTION_LOG_EVENT::CALC_SERVER_VERSION_SPLIT
Problem: When reading a Format_description_log_event, it supposes MySQL
version is always valid and DBUG_ASSERTION is used check the version number.
However, user may give a wrong binlog offset, even give a faked binary event
which includes an invalid MySQL version. This will cause server crash.
Fix: The assertions are removed and an error will be reported if MySQL
version in Format_description_log_event is invalid.
This bug had two problems:
P1) Reads out of bounds;
P2) Writes out of bounds.
PROBLEM P1
----------
User_var_log_event unmarshalling from binlog was not performing range
checks when using name_len and val_len variables to walk on event
buffer.
Added range checks to User_var_log_event unmarshalling to prevent
unmarshalling errors.
PROBLEM P2
----------
User_var_log_event value was allocated on thread stack, what caused
stack frame errors when User_var_log_event value was bigger than thread
stack size.
Currently value is allocated on heap memory.
QUOTING IN REPLICATION
Problem: Misquoting or unquoted identifiers may lead to
incorrect statements to be logged to the binary log.
Fix: we use specialized functions to append quoted identifiers in
the statements generated by the server.
Problem:
=======
The return value from my_b_write is ignored by: `my_b_write_quoted',
`my_b_write_bit',`Query_log_event::print_query_header'
Most callers of `my_b_printf' ignore the return value. `log_event.cc'
has many calls to it.
Analysis:
========
`my_b_write' is used to write data into a file. If the write fails it
sets appropriate error number and error message through my_error()
function call and sets the IO_CACHE::error == -1.
`my_b_printf' function is also used to write data into a file, it
internally invokes my_b_write to do the write operation. Upon
success it returns number of characters written to file and on error
it returns -1 and sets the error through my_error() and also sets
IO_CACHE::error == -1. Most of the event specific print functions
for example `Create_file_log_event::print', `Execute_load_log_event::print'
etc are the ones which make several calls to the above two functions and
they do not check for the return value after the 'print' call. All the above
mentioned abuse cases deal with the client side.
Fix:
===
As part of bug fix a check for IO_CACHE::error == -1 has been added at
a very high level after the call to the 'print' function. There are
few more places where the return value of "my_b_write" is ignored
those are mentioned below.
+++ mysys/mf_iocache2.c 2012-06-04 07:03:15 +0000
@@ -430,7 +430,8 @@
memset(buffz, '0', minimum_width - length2);
else
memset(buffz, ' ', minimum_width - length2);
- my_b_write(info, buffz, minimum_width - length2);
+++ sql/log.cc 2012-06-08 09:04:46 +0000
@@ -2388,7 +2388,12 @@
{
end= strxmov(buff, "# administrator command: ", NullS);
buff_len= (ulong) (end - buff);
- my_b_write(&log_file, (uchar*) buff, buff_len);
At these places appropriate return value handlers have been added.
Fixes for BUG11761686 left a flaw that managed to slip away from testing.
Only effective filtering branch was actually tested with a regression test
added to rpl_filter_tables_not_exist.
The reason of the failure is destuction of too early mem-root-allocated memory
at the end of the deferred User-var's do_apply_event().
Fixed with bypassing free_root() in the deferred execution branch.
Deallocation of created in do_apply_event() items is done by the base code
through THD::cleanup_after_query() -> free_items() that the parent Query
can't miss.
Problem
========
Replication breaks in the cases if the event length exceeds
the size of master Dump thread's max_allowed_packet.
The reason why this failure is occuring is because the event length is
more than the total size of the max_allowed_packet, on addition of the
max_event_header length exceeds the max_allowed_packet of the DUMP thread.
This causes the Dump thread to break replication and throw an error.
That can happen e.g with row-based replication in Update_rows event.
Fix
====
The problem is fixed in 2 steps:
1.) The Dump thread limit to read event is increased to the upper limit
i.e. Dump thread reads whatever gets logged in the binary log.
2.) On the slave side we increase the the max_allowed_packet for the
slave's threads (IO/SQL) by increasing it to 1GB.
This is done using the new server option (slave_max_allowed_packet)
included, is used to regulate the max_allowed_packet of the
slave thread (IO/SQL) by the DBA, and facilitates the sending of
large packets from the master to the slave.
This causes the large packets to be received by the slave and apply
it successfully.
Problem: mysqlbinlog exits without any error code in case of
file write error. It is because of the fact that the calls
to Log_event::print() method does not return a value and the
thus any error were being ignored.
Resolution: We resolve this problem by checking for the
IO_CACHE::error == -1 after every call to Log_event:: print()
and terminating the further execution.
Problem
========
SQL statements close to the size of max_allowed_packet produce binary
log events larger than max_allowed_packet.
The reason why this failure is occuring is because the event length is
more than the total size of the max_allowed_packet + max_event_header
length. Now since the event length exceeds this size master Dump
thread is unable to send the packet on to the slave.
That can happen e.g with row-based replication in Update_rows event.
Fix
====
The problem was fixed by increasing the max_allowed_packet for the
slave's threads (IO/SQL) by increasing it to 1GB.
This is done using the new server option included which is used to
regulate the max_allowed_packet of the slave thread (IO/SQL).
This causes the large packets to be received by the slave and apply
it successfully.
Problem: After the fix for Bug#12589870, a new field that
stores the length of db name was added in the buffer that
stores the query to be executed. Unlike for the plain user
session, the replication execution did not allocate the
necessary chunk in Query-event constructor. This caused an
invalid read while accessing this field.
Solution: We fix this problem by allocating a necessary chunk
in the buffer created in the Query_log_event::Query_log_event()
and store the length of database name.
BUG#11761686 insert_id event is not filtered.
Two issues are covered.
INSERT into autoincrement field which is not the first part in the composed primary key
is unsafe by autoincrement logging design. The case is specific to MyISAM engine
because Innodb does not allow such table definition.
However no warnings and row-format logging in the MIXED mode was done, and
that is fixed.
Int-, Rand-, User-var log-events were not filtered along with their parent
query that made possible them to screw up execution context of the following
query.
Fixed with deferring their execution until the parent query.
******
Bug#11754117
Post review fixes.
Analysis:
========================
sql_mode "NO_BACKSLASH_ESCAPES": When user want to use backslash as character input,
instead of escape character in a string literal then sql_mode can be set to
"NO_BACKSLASH_ESCAPES". With this mode enabled, backslash becomes an ordinary
character like any other.
SQL_MODE set applies to the current client session. And while creating the stored
procedure, MySQL stores the current sql_mode and always executes the stored
procedure in sql_mode stored with the Procedure, regardless of the server SQL
mode in effect when the routine is invoked.
In the scenario (for which bug is reported), the routine is created with
sql_mode=NO_BACKSLASH_ESCAPES. And routine is executed with the invoker sql_mode
is "" (NOT SET) by executing statement "call testp('Axel\'s')".
Since invoker sql_mode is "" (NOT_SET), the '\' in 'Axel\'s'(argument to function)
is considered as escape character and column "a" (of table "t1") values are
updated with "Axel's". The binary log generated for above update operation is as below,
set sql_mode=XXXXXX (for no_backslash_escapes)
update test.t1 set a= NAME_CONST('var',_latin1'Axel\'s' COLLATE 'latin1_swedish_ci');
While logging stored procedure statements, the local variables (params) used in
statements are replaced with the NAME_CONST(var_name, var_value) (Internal function)
(http://dev.mysql.com/doc/refman/5.6/en/miscellaneous-functions.html#function_name-const)
On slave, these logs are applied. NAME_CONST is parsed to get the variable and its
value. Since, stored procedure is created with sql_mode="NO_BACKSLASH_ESCAPES", the sql_mode
is also logged in. So that at slave this sql_mode is set before executing the statements
of routine. So at slave, sql_mode is set to "NO_BACKSLASH_ESCAPES" and then while
parsing NAME_CONST of string variable, '\' is considered as NON ESCAPE character
and parsing reported error for "'" (as we have only one "'" no backslash).
At slave, parsing was proper with sql_mode "NO_BACKSLASH_ESCAPES".
But above error reported while writing bin log, "'" (of Axel's) is escaped with
"\" character. Actually, all special characters (n, r, ', ", \, 0...) are escaped
while writing NAME_CONST for string variable(param, local variable) in bin log
Airrespective of "NO_BACKSLASH_ESCAPES" sql_mode. So, basically, the problem is
that logging string parameter does not take into account sql_mode value.
Fix:
========================
So when sql_mode is set to "NO_BACKSLASH_ESCAPES", escaping characters as
(n, r, ', ", \, 0...) should be avoided. To do so, added a check to not to
escape such characters while writing NAME_CONST for string variables in bin
log.
And when sql_mode is set to NO_BACKSLASH_ESCAPES, quote character "'" is
represented as ''.
http://dev.mysql.com/doc/refman/5.6/en/string-literals.html (There are several
ways to include quote characters within a string: )
HA_ERR was returning 0 (null string) when no error happened
(error=0). Since HA_ERR is used in DBUG_PRINT, regardless there
was an error or not, the server could crash in solaris debug
builds.
We fix this by:
- deploying an assertion that ensures that the function
is not called when no error has happened;
- making sure that HA_ERR is only called when an error
happened;
- making HA_ERR return "No Error", instead of 0, for
non-debug builds if it is called when no error happened.
This will make HA_ERR return values to work with DBUG_PRINT on
solaris debug builds.
The server crashes if it processes table map events that are
corrupted, especially if they map different tables to the same
identifier. This could happen, for instance, due to BUG 56226.
We fix this by checking whether the table map has already been
mapped before actually applying the event. If it has been mapped
with different settings an error is raised and the slave SQL
thread stops. If it has been mapped with same settings the event
is skipped. If the table is set to be ignored by the filtering
rules, there is no change in behavior: the event is skipped and
ids are not checked.
The slave was not able to find the correct row in the innodb
table, because the row fetched from the innodb table would not
match the before image. This happened because the (don't care)
bytes in the NULLed fields would change once the row was stored
in the storage engine (from zero to the default value). This
would make bulk memory comparison (using memcmp) to fail.
We fix this by taking a preventing measure and avoiding memcmp
for tables that contain nullable fields. Therefore, we protect
the slave search routine from engines that return arbitrary
values for don't care bytes (in the nulled fields). Instead, the
slave thread will only check null_bits and those fields that are
not set to NULL when comparing the before image against the
storage engine row.
mysqlbinlog only prints "use $database" statements to its output stream
when the active default database changes between events. This will cause
"No Database Selected" error when dropping and recreating that database.
To fix the problem, we clear print_event_info->db when printing an event
of CREATE/DROP/ALTER database statements, so that the Query_log_event
after such statements will be printed with the use 'db' anyway except
transaction keywords.
Normally, auto_increment value is generated for the column by
inserting either NULL or 0 into it. NO_AUTO_VALUE_ON_ZERO
suppresses this behavior for 0 so that only NULL generates
the auto_increment value. This behavior is also followed by
a slave, specifically by the SQL Thread, when applying events
in the statement format from a master. However, when applying
events in the row format, the flag was ignored thus causing
an assertion failure:
"Assertion failed: next_insert_id == 0, file .\handler.cc"
In fact, we never need to generate a auto_increment value for
the column when applying events in row format on slave. So we
don't allow it to happen by using 'MODE_NO_AUTO_VALUE_ON_ZERO'.
Refactoring: Get rid of all the sql_mode checks to rows_log_event
when applying it for avoiding problems caused by the inconsistency
of the sql_mode on slave and master as the sql_mode is not set for
Rows_log_event.
When a query fails with a different error on the slave,
the sql thread outputs a message (M) containing:
1. the error message format for the master error code
2. the master error code
3. the error message for the slave's error code
4. the slave error code
Given that the slave has no information on the error message
itself that the master outputs, it can only print its own
version of the message format (but stripped from the
additional data if the message format requires). This may
confuse users.
To fix this we augment the slave's message (M) to explicitly
state that the master's message is actually an error message
format, the one associated with the given master error code
and that the slave server knows about.
"Grantor" columns' data is lost when replicating mysql.tables_priv.
Slave SQL thread used its default user ''@'' as the grantor of GRANT|REVOKE
statements executing on it.
In this patch, current user is put in query log event for all GRANT and REVOKE
statement, SQL thread uses the user in query log event as grantor.
Rows events were applied wrongly on the temporary table with the same name.
But rows events are generated only for base tables. As temporary
table's data never be binlogged on row mode. Normally, base table of the
same name cannot be updated if a temporary table has the same name.
But there are two cases which can generate rows events on
the base table of same name.
Case1: 'CREATE TABLE ... SELECT' statement.
In mixed format, it will generate rows events if it is unsafe.
Case2: Drop a transactional temporary table in a transaction
(happens only on 5.5+).
BEGIN;
DROP TEMPORARY TABLE t1; # t1 is a InnoDB table
INSERT INTO t1 VALUES(rand()); # t1 is a MyISAM table
COMMIT;
'DROP TEMPORARY TABLE' will be put in the transaction cache and
binlogged after the rows events generated by the 'INSERT' statement.
After this patch, slave opens only base table when applying a rows event.
When slave executes a transaction bigger than slave's max_binlog_cache_size,
slave will crash. It is caused by the assert that server should only roll back
the statement but not the whole transaction if the error ER_TRANS_CACHE_FULL
happens. But slave sql thread always rollbacks the whole transaction when
an error happens.
Ather this patch, we always clear any error set in sql thread(it is different
from the error in 'SHOW SLAVE STATUS') and it is cleared before rolling back
the transaction.
Suprisingly, a Slave_log_event would show up in the binary
log. This event is never used and should not appear in the
logs. As such, when the slave (or the mysqlbinlog tool) reads the
event, it will hit an invalid pointer (reference to the
descriptor event when deserializing the Slave_log_event was
purposodely set to NULL).
The presence of the Slave_log_event denotes a corrupted log, but
we cannot tell how the log got corrupted in the first
place. However, we can make the server cope with such events when
it reads them - in case of log corruption - and fail gracefully.
This patch makes the server/mysqlbinlog to report that it has
found an invalid log event when Slave_log_event is read.
Although the C standard mandates that sprintf return the number
of bytes written, some very ancient systems (i.e. SunOS 4)
returned a pointer to the buffer instead. Since these systems
are not supported anymore and are hopefully long dead by now,
simply remove the portability wrapper that dealt with this
discrepancy. The autoconf check was causing trouble with GCC.
DROP USER
RENAME USER CURRENT_USER() ...
GRANT ... TO CURRENT_USER()
REVOKE ... FROM CURRENT_USER()
ALTER DEFINER = CURRENT_USER() EVENTbut, When these statements are binlogged, CURRENT_USER() just is binlogged
as 'CURRENT_USER()', it is not expanded to the real user name. When slave
executes the log event, 'CURRENT_USER()' is expand to the user of slave
SQL thread, but SQL thread's user name always NULL. This breaks the replication.
After this patch, session's user will be written into query log events
if these statements call CURREN_USER() or 'ALTER EVENT' does not assign a definer.
Apart strict-aliasing warnings, fix the remaining warnings
generated by GCC 4.4.4 -Wall and -Wextra flags.
One major source of warnings was the in-house function my_bcmp
which (unconventionally) took pointers to unsigned characters
as the byte sequences to be compared. Since my_bcmp and bcmp
are deprecated functions whose only difference with memcmp is
the return value, every use of the function is replaced with
memcmp as the special return value wasn't actually being used
by any caller.
There were also various other warnings, mostly due to type
mismatches, missing return values, missing prototypes, dead
code (unreachable) and ignored return values.
DROP USER
RENAME USER CURRENT_USER() ...
GRANT ... TO CURRENT_USER()
REVOKE ... FROM CURRENT_USER()
ALTER DEFINER = CURRENT_USER() EVENTbut, When these statements are binlogged, CURRENT_USER() just is binlogged
as 'CURRENT_USER()', it is not expanded to the real user name. When slave
executes the log event, 'CURRENT_USER()' is expand to the user of slave
SQL thread, but SQL thread's user name always NULL. This breaks the replication.
After this patch, session's user will be written into query log events
if these statements call CURREN_USER() or 'ALTER EVENT' does not assign a definer.
Post-push fix.
There was a valgrind issue on the loop that checks whether there
are NULL fields in the UNIQUE KEY or not. In detail, for the last
iteration the server may read out of the key_part array boundaries,
making valgrind to output warnings.
We fix this by correcting the loop, ie, moving the part that reads
from the key_part to be inside the loop statement block. This way
the assignment is protected by the loop condition.
When using Unique Keys with nullable parts in RBR, the slave can
choose the wrong row to update. This happens because a table with
an unique key containing nullable parts cannot strictly guarantee
uniqueness. As stated in the manual, for all engines, a UNIQUE
index allows multiple NULL values for columns that can contain
NULL.
We fix this at the slave by extending the checks before assuming
that the row found through an unique index is is the correct
one. This means that when a record (R) is fetched from the storage
engine and a key that is not primary (K) is used, the server does
the following:
- If K is unique and has no nullable parts, it returns R;
- Otherwise, if any field in the before image that is part of K
is null do an index scan;
- If there is no NULL field in the BI part of K, then return R.
A side change: renamed the existing test case file and added a
test case covering the changes in this patch.
This patch fixes two problems described as follows:
1 - If there is an on-going transaction and a temporary table is created or
dropped, any failed statement that follows the "create" or "drop commands"
triggers a rollback and by consequence the slave will go out sync because
the binary log will have a wrong sequence of events.
To fix the problem, we changed the expression that evaluates when the
cache should be flushed after either the rollback of a statment or
transaction.
2 - When a "CREATE TEMPORARY TABLE SELECT * FROM" was executed the
OPTION_KEEP_LOG was not set into the thd->options. For that reason, if
the transaction had updated only transactional engines and was rolled
back at the end (.e.g due to a deadlock) the changes were not written
to the binary log, including the creation of the temporary table.
To fix the problem, we have set the OPTION_KEEP_LOG into the thd->options
when a "CREATE TEMPORARY TABLE SELECT * FROM" is executed.
