MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6
If problems occur, such as that the new
mysqld server does not start, verify that
you do not have an old my.cnf
file from
your previous installation. You can check this with the
--print-defaults
option (for
example, mysqld --print-defaults). If this
command displays anything other than the program name, you
have an active my.cnf
file that affects
server or client operation.
If, after an upgrade, you experience problems with compiled
client programs, such as Commands out of
sync
or unexpected core dumps, you probably have
used old header or library files when compiling your programs.
In this case, check the date for your
mysql.h
file and
libmysqlclient.a
library to verify that
they are from the new MySQL distribution. If not, recompile
your programs with the new headers and libraries.
Recompilation might also be necessary for programs compiled
against the shared client library if the library major version
number has changed (for example, from
libmysqlclient.so.15
to
libmysqlclient.so.16
).
If you have created a user-defined function (UDF) with a given
name and upgrade MySQL to a version that implements a new
built-in function with the same name, the UDF becomes
inaccessible. To correct this, use DROP
FUNCTION
to drop the UDF, and then use
CREATE FUNCTION
to re-create
the UDF with a different nonconflicting name. The same is true
if the new version of MySQL implements a built-in function
with the same name as an existing stored function. See
Section 9.2.5, “Function Name Parsing and Resolution”, for the rules
describing how the server interprets references to different
kinds of functions.