WHEN STDIN IS A PIPE
Problem: Mysqlbinlog does not accept the input from STDIN when
STDIN is a pipe. This prevents the users from passing the input file
through a shell pipe.
Background: The my_seek() function does not check if the file descriptor
passed to it is regular (seekable) file. The check_header() function in
mysqlbinlog calls the my_b_seek() unconditionally and it fails when
the underlying file is a PIPE.
Resolution: We resolve this problem by checking if the underlying file
is a regular file by using my_fstat() before calling my_b_seek().
If the underlying file is not seekable we skip the call to my_b_seek()
in check_header().
client/mysqlbinlog.cc:
Added a check to avoid the my_b_seek() call if the
underlying file is a PIPE.
SHOW 2012 INSTEAD OF 2011
* Added a new macro to hold the current year :
COPYRIGHT_NOTICE_CURRENT_YEAR
* Modified ORACLE_WELCOME_COPYRIGHT_NOTICE macro
to take the initial year as parameter and pick
current year from the above mentioned macro.
AND LIBCRYPTO
Problem: libmysqlclient_r exports symbols from yaSSL library which
conflict with openSSL symbols. This issue is related to symbols
used by CURL library and are defined in taocrypt. Taocrypt has
dummy implementation of these functions. Due to this when a
program which uses libcurl library functions is compiled using
libmysqlclient_r and libcurl, it hits segmentation fault in
execution phase.
Solution: MySQL should not be exporting such symbols. However, these
functions are not used by MySQL code at all. So avoid compiling
them in the first place.
FOREVER MDL LOCK
Analysis:
----------
While granting MDL lock for the lock requests in wait queue,
first the lock is granted to the high priority lock types
and then to the low priority lock types.
MDL Priority Matrix,
+-------------+----+---+---+---+----+-----+
| Locks | | | | | | |
| has Priority| | | | | | |
| over ---> | S | SR| SW| SU| SNW| SNRW|
+-------------+----+---+---+---+----+-----+
| X | + | + | + | + | + | + |
+-------------|----|---|---|---|----|-----|
| SNRW | - | + | + | - | - | - |
+-------------|----|---|---|---|----|-----|
| SNW | - | - | + | - | - | - |
+-------------+----+---+---+---+----+-----+
Here '+' means, Lock priority is higher.
'-' means, Has same priority
In the scenario where,
*. Lock wait queue has requests of type S/SR/SW/SU.
*. And locks of high priority X/SNRW/SNW are requested
continuously.
In this case, while granting lock, always first high priority
lock requests(X/SNRW/SNW) are considered. Low priority
locks(S/SR/SW/SU) will not get chance and they will
wait forever.
In the scenario for which this bug is reported, application
executed many LOCK TABLES ... WRITE statements concurrently.
These statements request SNRW lock. Also there were some
connections trying to execute DML statements requesting SR
lock. Since SNRW lock request has higher priority (and as
they were too many waiting SNRW requests) lock is always
granted to it. So, lock request SR will wait forever, resulting
in DML starvation.
How is this handled in 5.1?
---------------------------
Even in 5.1 we have low priority lock starvation issue.
But, in 5.1 thread locking, system variable
"max_write_lock_count" can be configured to grant
some pending read lock requests. After
"max_write_lock_count" of write lock grants all the low
priority locks are granted.
Why this issue is seen in 5.5/trunk?
---------------------------------
In 5.5/trunk MDL locking, "max_write_lock_count" system
variable exists but not used in MDL, only thread lock uses
it. So no effect of "max_write_lock_count" in MDL locking.
This means that starvation of metadata locks is possible
even if max_write_lock_count is used.
Looks like, customer was using "max_write_lock_count" in
5.1 and when upgraded to 5.5, starvation is seen because
of not having effect of "max_write_lock_count" in MDL.
Fix:
----------
As a fix, support for max_write_lock_count is added to MDL.
To maintain write lock counter per MDL_lock object, new
member "m_hog_lock_count" is added in MDL_lock.
And following logic is added to increment the counter in
function reschedule_waiters,
(reschedule_waiters function is called while thread is
releasing the lock)
- After granting lock request from the wait queue.
- Check if there are any S/SR/SU/SW exists in the wait queue
- If yes then increment the "m_hog_lock_count"
And following logic is added in the same function to
handle pending S/SU/SR/SW locks
- Before granting locks
- Check if max_write_lock_count <= m_hog_lock_count
- If Yes, then try to grant S/SR/SW/SU locks.
(Since all of these has same priority, all locks are
granted together. But some lock grant may fail because
of grant incompatibility)
- Reset m_hog_lock_count if there no low priority lock
requests in wait queue.
- return
Note:
--------------------------
In the lock priority matrix explained above,
though X has priority over the SNW and SNRW. X locks is
taken mostly for RENAME, TRUNCATE, CREATE ... operations.
So lock type X may not be requested in loop continuously
in real world applications, as compared to other lock
request types. So, lock request of type SNW and SNRW are
not starved. So, we can grant all S/SR/SU/SW in one shot,
without considering SNW & SNRW lock request starvation.
ALTER table operations take SU lock first and then
upgrade to SNW if required. All S, SR, SW, SU have same
lock priority. So while granting SU, request of types
SR, SW, S are also granted in one shot. So, lock request
of type SU->SNW in loop will not make other low priority
lock request to starve.
But, when there is request for lock of type SNRW, lock
requests of lower priority types are not granted. And if
SNRW is requested in loop continuously then all
S, SR, SW, SU are starved.
This patch addresses the latter scenario.
When we have S/SR/SW/SU in wait queue and if
there are
- Continuous SNRW lock requests
- OR one or more X and Continuous SNRW lock requests.
- OR one SNW and Continuous SNRW lock requests.
- OR one SNW, one or more X and continuous SNRW lock
requests.
in wait queue then, S/SR/SW/SU lock request are starved.
mysql-test/suite/heap/heap.result:
Added test case for MDEV-436
mysql-test/suite/heap/heap.test:
Added test case for MDEV-436
storage/heap/hp_block.c:
Don't allocate a set of HP_PTRS when not needed. This saves us about 1024 bytes for most allocations.
storage/heap/hp_create.c:
Made the initial allocation of block sizes depending on min_records and max_records.
Backport the fix from 5.6 to 5.1
Base bug number : 11765562
sql/item_strfunc.cc:
In Item_func_export_set::val_str, verify that the size of the end
result is within reasonable bounds.
- When JOIN::cleanup(full==TRUE) is called, the select can be in two states:
= Right after the create_sort_index() call, when join->join_tab[0] is used to
read data produced by filesort().
= After create_sort_index(), and after JOIN::reinit() calls, when
join->join_tab[0] has been reset to read the original data.
- We didn't handle the second case correctly, which resulted in an attempt to free
the same SQL_SELECT two times. The fix is to make sure we don't double-free.
Following reasons caused mismatches:
- different handling of invalid values;
- different CAST results with fractional seconds;
- microseconds support in MariaDB;
- different algorithm of comparing temporal values;
- differences in error and warning texts and codes;
- different approach to truncating datetime values to time;
- additional collations;
- different record order for queries without ORDER BY;
- MySQL bug#66034.
More details in MDEV-369 comments.
make CMakeLists.txt to detect if the installed boost can be compiled with the
installed compile and specified set of compiler options.
Background: even sufficiently new Boost cannot be compiled with the sufficiently old gcc
in the presence of -fno-rtti
mysql_rm_table_no_locks() function was modified.
When we construct log record for the DROP TABLE, now we
look if there's a comment before the first table name and
add it to the record if so.
per-file comments:
sql/sql_table.cc
MDEV-340 Save replication comments for DROP TABLE.
comment_length() function implemented to find comments in the query,
call it in mysql_rm_table_no_locks() and use the result to form log record.
mysql-test/suite/binlog/r/binlog_drop_if_exists.result
MDEV-340 Save replication comments for DROP TABLE.
test result updated.
mysql-test/suite/binlog/t/binlog_drop_if_exists.test
MDEV-340 Save replication comments for DROP TABLE.
test case added.
Following reasons caused mismatches:
- different handling of invalid values;
- different CAST results with fractional seconds;
- microseconds support in MariaDB;
- different algorithm of comparing temporal values;
- differences in error and warning texts and codes;
- different approach to truncating datetime values to time;
- additional collations;
- different record order for queries without ORDER BY;
- MySQL bug#66034.
More details in MDEV-369 comments.
- Moved the definitions of the classes to store data from persistent
statistical tables into statistics.h, leaving in other internal
data structures only references to the corresponding objects.
- Defined class Column_statistics_collected derived from the class
Column_statistics. This is a helper class to collect statistics
on columns.
- Moved references to read statistics to TABLE SHARE, leaving the
the reference to the collected statistics in TABLE.
- Added a new clone method for the class Field allowing to clone
fields attached to table shares. It was was used to create
fields for min/max values in the memory of the table share.
A lso:
- Added procedures to allocate memory for statistical data in
the table share memory and in table memory.
Also:
- Added a test case demonstrating how ANALYZE could work in parallel
to collect statistics on different indexes of the same table.
- Added a test two demonstrate how two connections working
simultaneously could allocate memory for statistical data in the
table share memory.
- Add the vendor and release series checks from our traditional spec file,
to protect against errors during upgrade.
- Do some reformatting, to reduce the differences to our traditional spec file.
