Streams

Operations on Streams

• Get value by key – Get a value from the stream by key. If there is no such key in the stream, return null.

  Syntax: streamValue[ recordValue ]

  Type: The key must have the record type of the stream. The operation returns a value of the record type of the stream.

  Example: input_stream[ [k = 3; | ] ]

  Note: Non-key fields of the argument do not matter. The operation returns a record with the current values of the non-key fields, if a record with the key fields exists.

  If a key field is missing from the argument, or the key field is null, then this operation always returns null. It doesn't make sense to compare key fields in the stream to null, since null is never equivalent to any value (including null).

• Get value by match – Get a record from the stream that matches the given record. Unlike getting a value by key, there might be more than one matching record. If there is more than one matching record, one of the matching records is returned. If there is no such match in the stream, null is returned.

  Syntax: streamValue{ recordValue }

  Type: The record must be consistent with the record type of the stream. The operation returns a value of the record type of the stream.

  Example: input_stream{ [ | d = 5 ] }

  You can use key and non-key fields in the record.

You can also iterate through all the records in a stream using a "for" loop.