IDataView.GetRowCount Method
Definition
Important
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Returns the number of rows if known. Returning null means that the row count is unknown but it might return a non-null value on a subsequent call. This indicates, that the transform does not YET know the number of rows, but may in the future. Its implementation's computation complexity should be O(1).
Most implementation will return the same answer every time. Some, like a cache, might return null until the cache is fully populated.
public long? GetRowCount ();abstract member GetRowCount : unit -> Nullable<int64>Public Function GetRowCount () As Nullable(Of Long)