Class RowFilter.UserExpression

  • Enclosing class:
    RowFilter

    public abstract static class RowFilter.UserExpression
    extends RowFilter.Expression
    A user defined filtering expression. These may be added to RowFilter programmatically by a QueryHandler implementation. No concrete implementations are provided and adding custom impls to the classpath is a task for operators (needless to say, this is something of a power user feature). Care must also be taken to register implementations, via the static register method during system startup. An implementation and its corresponding Deserializer must be registered before sending or receiving any messages containing expressions of that type. Use of custom filtering expressions in a mixed version cluster should be handled with caution as the order in which types are registered is significant: if continuity of use during upgrades is important, new types should registered last and obsoleted types should still be registered ( or dummy implementations registered in their place) to preserve consistent identifiers across the cluster). During serialization, the identifier for the Deserializer implementation is prepended to the implementation specific payload. To deserialize, the identifier is read first to obtain the Deserializer, which then provides the concrete expression instance.