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Returns the number of records being read from the 'in' pipe during the current stream table processing cycle. This can be useful when deciding whether or not to read values from a pipe, for instance when using calculate streamstables.
countElements(in.AnyFieldName)
Also returns the number of records being read from the 'in' pipe, if AnyFieldName is an attribute that exists on the stream table being read from.
countElements(lookupPipe)
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