what is RowOrdinal property in Sharepoint FieldType Definition

Question

In Sharepoint it is not possible to add more than 16 Lookup-Fields to a single list. This limit is explained here: http://support.microsoft.com/?scid=kb%3Ben-us%3B823555&x=6&y=5

I found a workaround for it: The RowOrdinal-Property in FieldDefinition in schema.xml is default setted to = "0". You cann add more fields of one fieldtype than the limit by setting the "RowOrdinal"property for the 17th Lookup-Field to "1".It works.

The only disadvantage of this workaround is that a filter using this field doesn't work correctly.

Can anybody explain to me what is the RowOrdinal-Property for? Or has anyone another solution defining more than 16 Lookup-Fields in one single list?

Answer 1

I think you are using the RowOrdinal property as intended as you can find the following definition on MSDN:

tp_RowOrdinal: The zero-based ordinal index of this row in the set of rows representing the list item. Additional rows are used to represent list items that have more application-defined columns of one or more datatypes than can fit in a single row in the AllUserData table.

You can find the full description of the content database table columns here: http://msdn.microsoft.com/en-us/library/cc704499.aspx

But I do unfortunately not have an explanation why your lookup columns does not work as a filter.