TO INCONSISTENCY
PROBLEM
--------
When we drop a partitoned table , we first gather the
information about partitions in the table from the
table_name.par file and store it in an internal data
structure.Then we delete this file and the data in
the table. If the server crashes after deleting the
file,then after recovering we cannot access the table
.Even we cannot drop the table ,because drop algorithm
requires par file to read the partition information.
FIX
---
1. We move the part of deleting par file after deleting
all the table data from the storage egine.
2. During drop operation if we detect that the par
file is missing then we delete the .frm file,since
there is no way of recovering without par file.
[Approved by Mattias rb#2576 ]
ON DELETION ORDER
Problem:
When a InnoDB index page is under-filled, we will merge it with either
the left sibling node or the right sibling node. But this checking is
incorrect. When the left sibling node is available, even if merging
is not possible with left sibling node, we do not check for the
possibility of merging with the right sibling node.
Solution:
If left sibling node is available, and merging with left sibling node
is not possible, then check if merge with right sibling node is
possible.
rb#2506 approved by jimmy & ima.
CAN LEAD TO MISSING TABLES
Overview
--------
If the FOREIGN_KEY_CHECKS system variable is set to 0, it is
possible to break a foreign key constraint by changing the type
or character set of the foreign key column, or by dropping the
foreign key index (without carrying out corresponding changes on
another table in the relationship).
If we subsequently set FOREIGN_KEY_CHECKS to 1 and execute ALTER
TABLE involving the COPY algorithm on such a table, the following
happens:
1) If ALTER TABLE does not contain a RENAME clause, the attempt
to install the new version of the table instead of the old one
will fail due to the fact that the inconsistency will be
detected. An attempt to revert the partially executed alter
table operation by restoring the old table definition will
fail as well due to FOREIGN_KEY_CHECKS == 1. As a result, the
table being altered will be lost.
2) If ALTER TABLE contains the RENAME clause, the inconsistency
will not be detected (most probably due to other bugs). But if
an attempt to install the new version of the table fails (for
example, due to a failure when updating triggers associated
with the table), reverting the partially executed alter table
by restoring the old table definition will fail too. So the
table being altered might be lost as well.
Suggested fix
-------------
The suggested fix is to temporarily unset the option bit
representing FOREIGN_KEY_CHECKS when the old table definition is
restored while reverting the partially executed operation.
Bug#13116514 - CREATE LOGFILE GROUP INITIAL_SIZE & UNDO_BUFFER_SIZE FAILS
Fixing parser to accept the syntax: to give a size with suffix 'M', eg. undo_buffer_size=10M (M for mega bytes), in 'create logfile group' command.
i_s_innodb_buffer_page_get_info(): Do not read the buffer block frame
contents of read-fixed blocks, because it may be invalid or
uninitialized. When we are going to decompress or read a block, we
will put it into buf_pool->page_hash and buf_pool->LRU, read-fix the
block and release the mutexes for the duration of the reading or
decompression.
rb#2500 approved by Jimmy Yang
BY BINLOG_KILLED_SIMULATE.TEST
'mysqbinlog' tool creates a temporary file while
preparing LOAD DATA QUERY. These files needs to be deleted
at the end of the test script otherwise these files are
left out in the daily-run machines, causing
"no space on device issues"
Fix:
Delete them at the end of these test scripts
1) execute mysqlbinlog with --local-load option to
create these files in a specified tmpdir
2) delete the tmpdir at the end of the test script
STRING CONVERSION FUNCTIONS
Problem:
While executing the prepared statement, user variable is
set to memory which would be freed at the end of
execution.
If the statement is executed again, valgrind throws
error when accessing this pointer.
Analysis:
1. First time when Item_func_set_user_var::check is called,
memory is allocated for "value" to store the result.
(In the call to copy_if_not_alloced).
2. While sending the result, Item_func_set_user_var::check
is called again. But, this time, its called with
"use_result_field" set to true.
As a result, we call result_field->val_str(&value).
3. Here memory allocated for "value" gets freed. And "value"
gets set to "result_field", with "str_length" being that of
result_field's.
4. In the call to JOIN::cleanup, result_field's memory gets
freed as this is allocated in a chunk as part of the
temporary table which is needed to execute the query.
5. Next time, when execute of the same statement is called,
"value" will be set to memory which is already freed.
Valgrind error occurs as "str_length" is positive
(set at Step 3)
Note that user variables list is stored as part of the Lex object
in set_var_list. Hence the persistance across executions.
Solution:
Patch for Bug#11764371 fixed in mysql-5.6+ fixes this problem
as well.So backporting the same.
In the solution for Bug#11764371, we create another object of
user_var and repoint it to temp_table's field. As a result while
deleting the alloced buffer in Step 3, since the cloned object
does not own the buffer, deletion will not happen.
So at step 5 when we execute the statement second time, the
original object will be used and since deletion did not happen
valgrind will not complain about dangling pointer.
Bug#12608543: CRASHES WITH DECIMALS AND STATEMENT NEEDS TO BE REPREPARED ERRORS
Backporting these two fixes to 5.1
Added unittest to test my_decimal construtor and assignment operators
USING THE PLUGIN INTERFACE.
ISSUE: No support for floating-point plugin
system variables.
SOLUTION: Allowing plugins to define and expose floating-point
system variables of type double. MYSQL_SYSVAR_DOUBLE
and MYSQL_THDVAR_DOUBLE are added.
ISSUE: Fractional part of the def, min, max values of system
variables are ignored.
SOLUTION: Adding functions that are used to store the raw
representation of a double in the raw bits of unsigned
longlong in a way that the binary representation
remains the same.
ESCAPED WITH BACKSLASH
Problem:
When the CREATE TABLE statement used COMMENTS with escape sequences like
'foo\'s', InnoDB did not parse is correctly when trying to extract the
foreign key information. Because of this, the foreign keys specified
in the CREATE TABLE statement were not created.
Solution:
Make the InnoDB internal parser aware of escape sequences.
rb#2457 approved by Kevin.
MYSQL DB FROM REMOTE 5.0.96 SERVER
Problem: mysqldump tool assumes the existence of
general_log and slow_log tables in the server.
If mysqldump tool executes on a old server where
there are no log tables like these, mysqldump tool
fails.
Analysis: general_log and slow_log tables are added
in the ignore-table list as part of bug-26121 fix
causes bug-45740 (MYSQLDUMP DOESN'T DUMP GENERAL_LOG
AND SLOW_QUERY CAUSES RESTORE PROBLEM). As part of
the bug-45740 fix, mysqldump tool adds create table
queries for these two tables. But the fix assumes
that on all the servers, general_log and slow_log
will be there. If the new mysqldump tool is executed
against a old server where there are no general_log
and slow_log, the mysqldump tool fails with an error
that 'there is no general_log table'.
Fix: When mysqldump tool is trying to retrieve general_log
and slow_log table structures, first the tool should
check their existence of these tables in the server
instead of trying to dump it blindly.
The problem was in get_partition_id_cols_range_for_endpoint
and cmp_rec_and_tuple_prune, which stepped one partition too long.
Solution was to move a small portion of logic to cmp_rec_and_tuple_prune,
to simplify both get_partition_id_cols_range_for_endpoint and
get_partition_id_cols_list_for_endpoint.
INSERT BUFFER MERGE
Problem:
When the record is merged from the change buffer to the actual page,
in a particular condition, it is assumed that the deleted rec will
be re-used by the inserted rec. With this assumption the lock is
restored on the pointer to the deleted rec itself, thinking that
it is pointing to the newly inserted rec.
Solution:
Just before restoring the lock, update the rec pointer to point
to the newly inserted record. An assert has been added to verify
this. This assert will fail without the fix and will pass with
the fix.
rb#2449 in review by Marko and Jimmy
In order to keep error message numbers stable between GA releases, we
can not now add a new error message to 5.1/5.5 as this message would get
a number now used in 5.6.
This patch enforces this by adding a 5.1/5.5 specific check when processing
the error message file. If a new error message is added, building will
abort and report an error.
INSERT BUFFER MERGE
Problem:
When the record is merged from the change buffer to the actual page,
in a particular condition, it is assumed that the deleted rec will
be re-used by the inserted rec. With this assumption the lock is
restored on the pointer to the deleted rec itself, thinking that
it is pointing to the newly inserted rec.
Solution:
Just before restoring the lock, update the rec pointer to point
to the newly inserted record. An assert has been added to verify
this. This assert will fail without the fix and will pass with
the fix.
rb#2449 in review by Marko and Jimmy
INNODB_FAST_SHUTDOWN IS 2
Problem:
When innodb_fast_shutdown is set to 2 and the master thread enters
flush loop, under some circumstances it will not be able to exit it.
This may lead to a shutdown hanging.
This is happening because of the following:
1. In the flush_loop block of code, if the srv_fast_shutdown is
equal to 2 (very fast shutdown), then we do not flush dirty
pages in buffer pool to disk.
2. In the same flush_loop block of code, if the number of dirty
pages is more than user specified limit, we go to step 1.
This results in infinite loop.
Solution:
When we are in the process of doing a very fast shutdown, don't
do step 2 above.
rb#2328 approved by Inaam.
When a record contains no user data bytes (such as when the PRIMARY
KEY is an empty string and all secondary index fields are NULL or the
empty string), page_zip_decompress() could fail to set the record
heap_no correctly.
page_zip_decompress_node_ptrs(), page_zip_decompress_sec(),
page_zip_decompress_clust(): Set heap_no also at the end of the
compressed data stream.
rb#2448 approved by Jimmy Yang and Inaam Rana
AFTER A ROW IS READ
Approved by: Sunny Bains rb://2425
Don't release concurrency tickets when asked to release
btr_search_latch. This is a 5.5 only bug. It is already
fixed in 5.6 upwards.
