Server System Variables • have_symlink • histogram_generation_max_mem_size • host_cache_size YES  if symbolic link support is enabled,  NO  if not. This is required on Unix for support of the  DATA DIRECTORY  and  INDEX DIRECTORY  table options. If the server is started with the  --skip-symbolic- links  option, the value is  DISABLED . This variable has no meaning on Windows. Symbolic link support, along with the  --symbolic-links  option that controls it, is deprecated; expect these to be removed in a future version of MySQL. In addition, the option is disabled by default. The related  have_symlink  system variable also is deprecated and you should expect it to be removed in a future version of MySQL. The maximum amount of memory available for generating histogram statistics. See Section 8.9.6, “Optimizer Statistics” , and Section 13.7.3.1, “ANALYZE TABLE Statement” . Setting the session value of this system variable is a restricted operation. The session user must have privileges sufficient to set restricted session variables. See Section 5.1.9.1, “System Variable Privileges” . 806 Note Command-Line Format --histogram-generation-max-mem-size=# System Variable histogram_generation_max_mem_size Scope Global, Session Dynamic Yes SET_VAR  Hint Applies No Type Integer Default Value 20000000 Minimum Value 1000000 Maximum Value (64-bit platforms) 18446744073709551615 Maximum Value (32-bit platforms) 4294967295 Command-Line Format --host-cache-size=# System Variable host_cache_size Scope Global Dynamic Yes SET_VAR  Hint Applies No Type Integer Default Value -1  (signifies autosizing; do not assign this literal value) Minimum Value 0