ColumnFilter
Prior to MDS 13.0, new GetClassObject and Get Collection routines in the MetaActive Class return all the properties for an object. This can be time consuming if only a few of the unique properties are needed.
The following routines provide the ability to specify and restrict the unique properties to be returned through the used of a ColumnFilter parameter:
If the ColumnFilter parameter for these routines is NULL (or the IMetaInfoKeyList is empty) all unique properties of every object are returned by the method call. This is the same behavior as that of the previous version of the call.
Specify only those unique properties to be returned by adding an IMetaInfoKey object, with its ObjectID set to the Property ID (PID) of the property, for each property needed, to the ColumnFilter list.
Depending on the number of objects and the number of unique properties not needed, and therefore not returned, this can result in a significant savings in time, and database spool-space. (The SQL generated by the MDS engine requests only those columns (properties) specified when it builds the SELECT statement.)
For security and other reasons, all "common" properties are always returned, with the exception of the Description and ObjectGUID properties. When unique properties are specified in the ColumnFilter list, these two common properties will have empty and NULLGUID values respectively, unless their PIDs are also added to the ColumnFilter list. (Note: the PIDs for common properties can be found in the MetaGlobals_h.bas file.)