If configure is run after it has previously been run, it may use information that was gathered during its previous invocation. This information is stored in config.cache. When configure starts up, it looks for that file and reads its contents if it exists, on the assumption that the information is still correct. That assumption is invalid when you reconfigure.

Each time you run configure, you must run make again to recompile. However, you may want to remove old object files from previous builds first because they were compiled using different configuration options.

If you get errors such as the ones shown here when compiling sql_yacc.cc, you probably have run out of memory or swap space:

Internal compiler error: program cc1plus got fatal signal 11
Out of virtual memory
Virtual memory exhausted

The problem is that gcc requires a huge amount of memory to compile sql_yacc.cc with inline functions. Try running configure with the --with-low-memory option:

shell> ./configure --with-low-memory

This option causes -fno-inline to be added to the compile line if you are using gcc and -O0 if you are using something else. You should try the --with-low-memory option even if you have so much memory and swap space that you think you can't possibly have run out. This problem has been observed to occur even on systems with generous hardware configurations, and the --with-low-memory option usually fixes it.

By default, configure picks c++ as the compiler name and GNU c++ links with -lg++. If you are using gcc, that behavior can cause problems during configuration such as this:

configure: error: installation or configuration problem:
C++ compiler cannot create executables.

You might also observe problems during compilation related to g++, libg++, or libstdc++.

One cause of these problems is that you may not have g++, or you may have g++ but not libg++, or libstdc++. Take a look at the config.log file. It should contain the exact reason why your C++ compiler didn't work. To work around these problems, you can use gcc as your C++ compiler. Try setting the environment variable CXX to "gcc -O3". For example:

shell> CXX="gcc -O3" ./configure

This works because gcc compiles C++ source files as well as g++ does, but does not link in libg++ or libstdc++ by default.

Another way to fix these problems is to install g++, libg++, and libstdc++. However, do not use libg++ or libstdc++ with MySQL because this only increases the binary size of mysqld without providing any benefits. Some versions of these libraries have also caused strange problems for MySQL users in the past.

If your compile fails with errors such as any of the following, you must upgrade your version of make to GNU make:

making all in mit-pthreads
make: Fatal error in reader: Makefile, line 18:
Badly formed macro assignment

Or:

make: file `Makefile' line 18: Must be a separator (:

Or:

pthread.h: No such file or directory

Solaris and FreeBSD are known to have troublesome make programs.

GNU make 3.75 is known to work.

If you want to define flags to be used by your C or C++ compilers, do so by adding the flags to the CFLAGS and CXXFLAGS environment variables. You can also specify the compiler names this way using CC and CXX. For example:

shell> CC=gcc
shell> CFLAGS=-O3
shell> CXX=gcc
shell> CXXFLAGS=-O3
shell> export CC CFLAGS CXX CXXFLAGS

See Installing MySQL from Generic Binaries on Unix/Linux, for a list of flag definitions that have been found to be useful on various systems.

If you get errors such as those shown here when compiling mysqld, configure did not correctly detect the type of the last argument to accept(), getsockname(), or getpeername():

cxx: Error: mysqld.cc, line 645: In this statement, the referenced
     type of the pointer value ''length'' is ''unsigned long'',
     which is not compatible with ''int''.
new_sock = accept(sock, (struct sockaddr *)&cAddr, &length);

To fix this, edit the config.h file (which is generated by configure). Look for these lines:

/* Define as the base type of the last arg to accept */
#define SOCKET_SIZE_TYPE XXX

Change XXX to size_t or int, depending on your operating system. (You must do this each time you run configure because configure regenerates config.h.)

The sql_yacc.cc file is generated from sql_yacc.yy. Normally, the build process does not need to create sql_yacc.cc because MySQL comes with a pre-generated copy. However, if you do need to re-create it, you might encounter this error:

"sql_yacc.yy", line xxx fatal: default action causes potential...

This is a sign that your version of yacc is deficient. You probably need to install bison (the GNU version of yacc) and use that instead.

On Debian Linux 3.0, you need to install gawk instead of the default mawk.

If you need to debug mysqld or a MySQL client, run configure with the --with-debug option, and then recompile and link your clients with the new client library. See MySQL Internals: Porting.

If you get a compilation error on Linux (for example, SuSE Linux 8.1 or Red Hat Linux 7.3) similar to the following one, you probably do not have g++ installed:

libmysql.c:1329: warning: passing arg 5 of `gethostbyname_r' from
incompatible pointer type
libmysql.c:1329: too few arguments to function `gethostbyname_r'
libmysql.c:1329: warning: assignment makes pointer from integer
without a cast
make[2]: *** [libmysql.lo] Error 1

By default, the configure script attempts to determine the correct number of arguments by using g++ (the GNU C++ compiler). This test yields incorrect results if g++ is not installed. There are two ways to work around this problem:

You must run configure again after making either of those changes.