mysql-3.22.20a, mysql.info, node "Symbolic links", says
Using symbolic links for databases and tables
*MySQL* doesn't support linking of databases by default. Things will
work fine as long as you don't make a symbolic link between databases.
Suppose you have a database `db1' under the *MySQL* data directory, and
then make a symlink `db2' that points to `db1':
shell> cd /path/to/datadir
shell> ln -s db1 db2
Now, for any table `tbl_a' in `db1', there also appears to be a table
`tbl_a' in `db2'. If one thread updates `db1.tbl_a' and another thread
updates `db2.tbl_a', there will be problems.
If you really need this, you must change the following code in
if (!lstat(to,&stat_buff)) /* Check if it's a symbolic link */
if (S_ISLNK(stat_buff.st_mode) && realpath(to,buff))
Change the code to this:
But I see in mf_format.c that flag bit 32 will get the second (symlink-aware)
behavior. How do I set this flag bit?