This associates a value to the name in the Database registry. The name should be a string and the value must be also string.
Registry settings are kept in Database, therefore they are persistent.
Some registry variables are used solely by internal server routines so they should not be set by any application. Some of these "protected" variables can be updated by DBA only (in built-in Virtuoso/PL routines) whereas some can not be updated by any Virtuoso/PL routine at all. If the function is called by DBA then a third argument can be specified to indicate how the function should try to update such a variable, but you will probably never use this feature.
The function returns 1 if success, 0 if a (protected) variable value cannot be changed.
From SQL
SQL> select registry_get('var_demo'); callret VARCHAR __________________________________________________________________ NULL SQL> registry_set('var_demo', 'some arb data'); SQL> select registry_get('var_demo'); callret VARCHAR __________________________________________________________________ some arb data