IS PLACE HOLDER AND USE SERVER-SIDE
Analysis:
LIMIT always takes nonnegative integer constant values.
http://dev.mysql.com/doc/refman/5.6/en/select.html
So parsing of value '5' for LIMIT in SELECT fails.
But, within prepared statement, LIMIT parameters can be
specified using '?' markers. Value for the parameter can
be supplied while executing the prepared statement.
Passing string values, float or double value for LIMIT
works well from CLI. Because, while setting the value
for the parameters from the variable list (added using
SET), if the value is for parameter LIMIT then its
converted to integer value.
But, when prepared statement is executed from the other
interfaces as J connectors, or C applications etc.
The value for the parameters are sent to the server
with execute command. Each item in log has value and
the data TYPE. So, While setting parameter value
from this log, value is set to all the parameters
with the same data type as passed.
But here logic to convert value to integer type
if its for LIMIT parameter is missing.
Because of this,string '5' is set to LIMIT.
And the same is logged into the binlog file too.
Fix:
When executing prepared statement having parameter for
CLI it worked fine, as the value set for the parameter
is converted to integer. And this failed in other
interfaces as J connector,C Applications etc as this
conversion is missing.
So, as a fix added check while setting value for the
parameters. If the parameter is for LIMIT value then
its converted to integer value.
WORK + SAVES ROOT PASSWORD TO DISK!
The secure installation scripts connect to the
server by storing the password in a temporary
option file. Now, if the script gets killed or
fails for some reason, the removal of the option
file may not take place.
This patch introduces following enhancements :
* (.sh) Made sure that cleanup happens at every
call to 'exit 1'. This is performed implicitly
by END{} in pl.in.
* (.pl.in) Added a warning in case unlink fails
to delete the option/query files.
* (.sh/.pl.in) Added more signals to the signal
handler list. SIG# 1, 3, 6, 15
Problem description:
Table 't' created with two colums having compound index on both the
columns under innodb/myisam engine at remote machine. In the local
machine same table is created undet the federated engine.
A select having where clause with along 'AND' operation gives wrong
results on local machine.
Analysis:
The given query at federated engine is wrongly transformed by
federated::create_where_from_key() function and the same was sent to
the remote machine. Hence the local machine is showing wrong results.
Given query "select c1 from t where c1 <= 2 and c2 = 1;"
Query transformed, after ha_federated::create_where_from_key() function is:
SELECT `c1`, `c2` FROM `t` WHERE (`c1` IS NOT NULL ) AND
( (`c1` >= 2) AND (`c2` <= 1) ) and the same sent to real_query().
In the above the '<=' and '=' conditions were transformed to '>=' and
'<=' respectively.
ha_federated::create_where_from_key() function behaving as below:
The key_range is having both the start_key and end_key. The start_key
is used to get "(`c1` IS NOT NULL )" part of the where clause, this
transformation is correct. The end_key is used to get "( (`c1` >= 2)
AND (`c2` <= 1) )", which is wrong, here the given conditions('<=' and '=')
are changed as wrong conditions('>=' and '<=').
The end_key is having {key = 0x39fa6d0 "", length = 10, keypart_map = 3,
flag = HA_READ_AFTER_KEY}
The store_length is having value '5'. Based on store_length and length
values the condition values is applied in HA_READ_AFTER_KEY switch case.
The switch case 'HA_READ_AFTER_KEY' is applicable to only the last part of
the end_key and for previous parts it is going to 'HA_READ_KEY_OR_NEXT' case,
here the '>=' is getting added as a condition instead of '<='.
Fix:
Updated the 'if' condition in 'HA_READ_AFTER_KEY' case to affect for all
parts of the end_key. i.e 'i > 0' will used for end_key, Hence added it in
the if condition.
Backporting the WL#5716, "Information schema table for InnoDB
buffer pool information". Backporting revisions 2876.244.113,
2876.244.102 from mysql-trunk.
rb://1175 approved by Jimmy Yang.
Problem description:
Giving "help 'contents'" in the mysql client as a first statement
gives error
Analysis:
In com_server_help() function the "server_cmd" variable was
initialised with buffer->ptr(). And the "server_cmd" variable is not
updated since we are passing "'contents'"(with single quote) so the
buffer->ptr() consists of the previous buffer values and it was sent
to the mysql_real_query() hence we are getting error.
Fix:
We are not initialising the "server_cmd" variable and we are updating
the variable with "server_cmd= cmd_buf" in any of the case i.e with
single quote or without single quote for the contents.
As part of error message improvement, added new error message in case
of "help 'contents'".
"ORDER BY" AND "LIMIT BY" CLAUSE
PROBLEM:
When a 'limit' clause is specified in a query along with
group by and order by, optimizer chooses wrong index
there by examining more number of rows than required.
However without the 'limit' clause, optimizer chooses
the right index.
ANALYSIS:
With respect to the query specified, range optimizer chooses
the first index as there is a range present ( on 'a'). Optimizer
then checks for an index which would give records in sorted
order for the 'group by' clause.
While checking chooses the second index (on 'c,b,a') based on
the 'limit' specified and the selectivity of
'quick_condition_rows' (number of rows present in the range)
in 'test_if_skip_sort_order' function.
But, it fails to consider that an order by clause on a
different column will result in scanning the entire index and
hence the estimated number of rows calculated above are
wrong (which results in choosing the second index).
FIX:
Do not enforce the 'limit' clause in the call to
'test_if_skip_sort_order' if we are creating a temporary
table. Creation of temporary table indicates that there would be
more post-processing and hence will need all the rows.
This fix is backported from 5.6. This problem is fixed in 5.6 as
part of changes for work log #5558
RBR AND RC
Description: When scanning and locking rows with < or <=, InnoDB locks
the next row even though row based binary logging and read committed
is used.
Solution: In the handler, when the row is identified to fall outside
of the range (as specified in the query predicates), then request the
storage engine to unlock the row (if possible). This is done in
handler::read_range_first() and handler::read_range_next().
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.
HANDLE_FATAL_SIGNAL IN STRNLEN
Fixed the following bounds checking problems :
1. in check_if_legal_filename() make sure the null terminated
string is long enough before accessing the bytes in it.
Prevents pottential read-past-buffer-end
2. in my_wc_mb_filename() of the filename charset check
for the end of the destination buffer before sending single
byte characters into it.
Prevents write-past-end-of-buffer (and garbaling stack in
the cases reported here) errors.
Added test cases.
This is a followup patch for the bug enabling the test
i_binlog.binlog_mysqlbinlog_file_write.test
this was disabled in mysql trunk and mysql 5.5 as in the release
build mysqlbinlog was not debug compiled whereas the mysqld was.
Since have_debug.inc script checks only for mysqld to be debug
compiled, the test was not being skipped on release builds.
We resolve this problem by creating a new inc file
mysqlbinlog_have_debug.inc which checks exclusively for mysqlbinlog
to be debug compiled. if not it skips the test.
Several fixes :
* sql-common/client.c
Added a validity check of the fields metadata packet sent
by the server.
Now libmysql will check if the length of the data sent by
the server matches what's expected by the protocol before
using the data.
* client/mysqltest.cc
Fixed the error handling code in mysqltest to avoid sending
new commands when the reading the result set failed (and
there are unread data in the pipe).
* sql_common.h + libmysql/libmysql.c + sql-common/client.c
unpack_fields() now generates a proper error when it fails.
Added a new argument to this function to support the error
generation.
* sql/protocol.cc
Added a debug trigger to cause the server to send a NULL
insted of the packet expected by the client for testing
purposes.
Print the warning(note):
YEAR(x) is deprecated and will be removed in a future release. Please use YEAR(4) instead
on "CREATE TABLE ... YEAR(x)" or "ALTER TABLE MODIFY ... YEAR(x)", where x != 4
a multiple definition of 'THD::clear_error()' in (at least)
libmysqld.a(lib_sql.o) and libmysqld.a(libfederated_a-ha_federated.o).
Patch provided by Ramil Kalimullin.
Problem: Some queries with subqueries and a HAVING clause that
consists only of a column not in the select or grouping lists causes
the server to crash.
During parsing, an Item_ref is constructed for the HAVING column. The
name of the column is resolved when JOIN::prepare calls fix_fields()
on its having clause. Since the column is not mentioned in the select
or grouping lists, a ref pointer is not found and a new Item_field is
created instead. The Item_ref is replaced by the Item_field in the
tree of HAVING clauses. Since the tree consists only of this item, the
pointer that is updated is JOIN::having. However,
st_select_lex::having still points to the Item_ref as the root of the
tree of HAVING clauses.
The bug is triggered when doing filesort for create_sort_index(). When
find_all_keys() calls select->cond->walk() it eventually reaches
Item_subselect::walk() where it continues to walk the having clauses
from lex->having. This means that it finds the Item_ref instead of the
new Item_field, and Item_ref::walk() tries to dereference the ref
pointer, which is still null.
The crash is reproducible only in 5.5, but the problem lies latent in
5.1 and trunk as well.
Fix: After calling fix_fields on the having clause in JOIN::prepare(),
set select_lex::having to point to the same item as JOIN::having.
This patch also fixes a bug in 5.1 and 5.5 that is triggered if the
query is executed as a prepared statement. The Item_field is created
in the runtime arena when the query is prepared, and the pointer to
the item is saved by st_select_lex::fix_prepare_information() and
brought back as a dangling pointer when the query is executed, after
the runtime arena has been reclaimed.
Fix: Backport fix from trunk that switches to the permanent arena
before calling Item_ref::fix_fields() in JOIN::prepare().
INC_HOST_ERRORS() IS CALLED.
Issue : Sequence of calling inc_host_errors()
and reset_host_errors() required some
changes in order to maintain correct
connection error count.
Solution : Call to reset_host_errors() is shifted
to a location after which no calls to
inc_host_errors() are made.
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.
WHEN KILLING
Suppose there is a query waiting for a lock. If the user kills
this query, then "Got error -1 when reading table" error message
must not be logged in the server log file. Since this is a user
requested interruption, no spurious error message must be logged
in the server log. This patch will remove the error message from
the log.
approved by joh and tatjana
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.
rb://1088
approved by: Marko Makela
This bug was introduced in early stages of plugin. We were not
checking for an implicit lock on sec index rec for trx_id that is
stamped on current version of the clust_index in case where the
clust_index has a previous delete marked version.
