This is a regression from the fix for bug no 38999. A storage engine capable
of reading only a subset of a table's columns updates corresponding bits in
the read buffer to signal that it has read NULL values for the corresponding
columns. It cannot, and should not, update any other bits. Bug no 38999
occurred because the implementation of UPDATE statements compare the NULL bits
using memcmp, inadvertently comparing bits that were never requested from the
storage engine. The regression was caused by the storage engine trying to
alleviate the situation by writing to all NULL bits, even those that it had no
knowledge of. This has devastating effects for the index merge algorithm,
which relies on all NULL bits, except those explicitly requested, being left
unchanged.
The fix reverts the fix for bug no 38999 in both InnoDB and InnoDB plugin and
changes the server's method of comparing records. For engines that always read
entire rows, we proceed as usual. For engines capable of reading only select
columns, the record buffers are now compared on a column by column basis. An
assertion was also added so that non comparable buffers are never read. Some
relevant copy-pasted code was also consolidated in a new function.
The subtime function wasn't able to produce correct int representation of
its result. For constant expressions the Item_datetime_cache is used to
speedup evaluation and Item_datetime_cache expects underlying item to return
correct int representation of DATETIME value. These two factors combined led
to a wrong query result.
Now the Item_func_add_time has function val_datetime which performs the
calculation and saves result into given MYSQL_TIME struct, it also sets
null_value to appropriate value. val_int and val_str member functions
convert the result obtained from val_datetime to int or string respectively
and returns it.
The fix is to:
- introduce ORACLE_WELCOME_COPYRIGHT_NOTICE define to have a single place
to specify copyright notice;
- replace custom copyright notices with ORACLE_WELCOME_COPYRIGHT_NOTICE
in programs.
Problem: CASE didn't work with a mixture of different character
sets in THEN/ELSE in some cases.
This happened because after character set aggregation
newly created Item_func_conv_charset items corresponding
to THEN/ELSE arguments were not put back to args[] array.
Fix:
put all Item_func_conv_charset back to args[].
@ mysql-test/include/ctype_numconv.inc
@ mysql-test/r/ctype_ucs.result
Adding tests
@ sql/item_cmpfunc.cc
Put "agg" back to args[] after character set aggregation.
error flushing io cache
The reason for the error was incorrect return code from
my_win_write() in case of error on 64 bit Windows.
Error should be indicated by return code
(size_t)-1 == 2^64 -1, but due to cast it was
(DWORD)-1 = 2^32 -1
The caller of this function would fail to recognize the error
and continue looping.
Fix is to return correct error code (size_t)-1 in case of error
as expected by caller.
Also minimal cleanup is done : my_win_write() now uses
the same parameter checks as related functions (0 and
overflow handling for count parameter).
- fix ~20 warnings about redefinition of HAVE_DLOPEN
This was caused by new ADD_DEFINITIONS(-DHAVE_DLOPEN) inside client library CMakeLists.txt
- fix dlerror() message which ("static build?" ) which is only confusing on Windows,
there is no "static build"
The error was introduced by typo in variable name (errormsg instead of correct
errmsg)
- Also, precache HAVE_PEERCRED to OFF in cmake\os\WindowsCache.cmake
(to avoid useless system check).
- Also, add missing check for errors from FormatMessage().
- Also, remove annoying CMake debug printout of MALLOC_LIB if this is not set.
connectors plugins
Implemented changes needed to keep the client plugin API compatible with
the existing plugins :
1. Provided an options() client plugin API to let the application pass
options to the plugin after loading it
2. Added "License" (const char *) to specify the client plugin's license
3. Added "mysql_api" as a placeholder that the client library can use
to pass function pointers to the plugin so that the plugin can call the
C lib back.
4. Updated the existing client plugins to comply with the API change.
5. Added more detailed error message generation for Windows.
Quoting from the bug report:
The pstack library has been included in MySQL since version
4.0.0. It's useless and should be removed.
Details: According to its own documentation, pstack only works
on Linux on x86 in 32 bit mode and requires LinuxThreads and a
statically linked binary. It doesn't really support any Linux
from 2003 or later and doesn't work on any other OS.
detector". This patch addresses performance regression in OLTP_RO/MyISAM
test on Windows introduced by the fix for bug #56405. Thus it makes
original patch acceptable as a solution for bug #56585 "Slowdown of
readonly sysbench benchmarks (e.g point_select) on Windows 5.5".
With this patch, MySQL will use native Windows condition variables and
reader-writer locks if they are supported by the OS.
This speeds up MyISAM and the effect comes mostly from using native
rwlocks. Native conditions improve scalability with higher number of
concurrent users in other situations, e.g for prlocks.
Benchmark numbers for this patch as measured on Win2008R2 quad
core machine are attached to the bug report.
( direct link http://bugs.mysql.com/file.php?id=15883 )
Note that currently we require at least Windows7/WS2008R2 for
reader-writer locks, even though native rwlock is available also on Vista.
Reason is that "trylock" APIs are missing on Vista, and trylock is used in
the server (in a single place in query cache).
While this patch could have been written differently, to enable the native
rwlock optimization also on Vista/WS2008 (e.g using native locks everywhere
but portable implementation in query cache), this would come at the
expense of the code clarity, as it would introduce a new "try-able" rwlock
type, to handle Vista case.
Another way to improve performance for the special case
(OLTP_RO/MYISAM/Vista) would be to eliminate "trylock" usage from server,
but this is outside of the scope here.
Native conditions variables are used beginning with Vista though the effect
of using condition variables alone is not measurable in this benchmark.
But when used together with native rwlocks on Win7, native conditions improve
performance in high-concurrency OLTP_RO/MyISAM (128 and more sysbench
users).
