MySQL 5.7 Release Notes
If you have some very specific problem, you can always try to
debug MySQL. To do this you must configure MySQL with the
-DWITH_DEBUG=1 option. You can
check whether MySQL was compiled with debugging by doing:
mysqld --help. If the
--debug flag is listed with the
options then you have debugging enabled. mysqladmin
ver also lists the mysqld version
as mysql ... --debug in this case.
If mysqld stops crashing when you configure
it with the -DWITH_DEBUG=1 CMake
option, you probably have found a compiler bug or a timing bug
within MySQL. In this case, you can try to add
-g using the
CMAKE_C_FLAGS and
CMAKE_CXX_FLAGS CMake options and
not use -DWITH_DEBUG=1. If
mysqld dies, you can at least attach to it
with gdb or use gdb on the
core file to find out what happened.
When you configure MySQL for debugging you automatically enable
a lot of extra safety check functions that monitor the health of
mysqld. If they find something
“unexpected,” an entry is written to
stderr, which mysqld_safe
directs to the error log! This also means that if you are having
some unexpected problems with MySQL and are using a source
distribution, the first thing you should do is to configure
MySQL for debugging. If you believe that you have found a bug,
please use the instructions at Section 1.5, “How to Report Bugs or Problems”.
In the Windows MySQL distribution, mysqld.exe
is by default compiled with support for trace files.