Configuration interface of pluggable storage engines

[Marko Mäkelä]

I have been informed that in MySQL 5.1, pluggable storage engines will be
able to declare their own configuration parameters and settable variables.
In struct st_mysql_plugin (include/mysql/plugin.h), there are three
fields for this:

  struct st_mysql_show_var *status_vars;
  void * __reserved1;   /* placeholder for system variables */
  void * __reserved2;   /* placeholder for config options */

I would have expected to find an example of the usage in
storage/example/ha_example.cc.  Alas, all three fields are initialized
to NULL there, just like in every other storage engine that is currently
available at bk://mysql.bkbits.net/mysql-5.1.  I checked all storage
engines except ndb; I couldn't find a reference to the handler class in
the ndb source tree.

When will this be implemented?  I hope that the __reserved1 and
__reserved2 will be function pointers, because that would allow the
storage engine to be notified when a change is requested.  That kind of
functionality would be desired for resizing the InnoDB buffer pool at
runtime.

	Marko Mäkelä
	Innobase Oy/Oracle Corp.