Hi, MARK! On Nov 29, MARK CALLAGHAN wrote:

Is there an easy way to prevent SET GLOBAL ... from being done for plugin variables declared via MYSQL_THDVAR_...? For the following variable I can do SET GLOBAL innodb_fake_changes=1 and that sets a global variable.

static MYSQL_THDVAR_BOOL(fake_changes, PLUGIN_VAR_OPCMDARG, "In the transaction after enabled, UPDATE, INSERT and DELETE only move the cursor to the records " "and do nothing other operations (no changes, no ibuf, no undo, no transaction log) in the transaction. " "This is to cause replication prefetch IO. ATTENTION: the transaction started after enabled is affected.", check_fake_changes, NULL, FALSE);

I couldn't find a proper solution, but here's a workaround. Provide an update function for your variable: - check_fake_changes, NULL, FALSE); + check_fake_changes, update_fake_changes, FALSE); + + void update_fake_changes(MYSQL_THD thd, struct st_mysql_sys_var *var, + void *var_ptr, const void *save) + { + if (var_ptr != THDVAR(0, fake_changes)) + *(my_bool *) var_ptr= *(my_bool *) save ? TRUE : FALSE; + } it isn't very cool, because one is supposed to do all the checks in the check function, not in the update. but it'll work. Regards, Sergei