Map operator

Performs a mapping of incoming attributes to out-coming attributes using map functions. Odysseus also provides a wide range of mapping functions.

Hint: Map is stateless. To used Map in a statebased fashion see: StateMap

Parameter

• expressions: A list of expressions to map multiple incoming attribute values to out-coming attributes. Optional each expression can have a name (in this case use ['expression', 'expressionName'])
• threads: Number of threads used to process the expressions simultaneous. A positive number greater than 1 indicates the fixed number of threads, a value of 0 or 1 disables threading, and a negative number estimates the number of threads based on the number of expressions and the available processors.

• allownull: If set to true (default) and an error occurs in calculation a null value is added to the element. Else the element is skipped and no output is produced. Default is true.

• kvexpressions: Same as expressions, but for key value objects. (only for use with key value objects)
• keepAttributes: If set to true, all key value pairs will be kept, even if not mentioned in kvexpressions. (only for use with key value objects)
• removeAttribtues:A List of attributes, which will be removed from the key value object. (only for use with key value objects)

Example

PQL

output = MAP({
              expressions = [
								['auction_id * 5','AuctionMult5'],
								'sqrt(auction_id)'
							]
             }, input)

///Example for use with key value objects
kvoutput = MAP({
				kvExpressions = [
									['toLong(timestamp.unixtimestamp + 1)', 'Zeit']
                            	],
                keepAllAttributes = 'true',
                removeAttributes = ['uncorrectedTrack.mbid', 'track.artist.mbid', 'track.mbid', 'uncorrectedTrack.artist.mbid']
			}, json)

CQL

SELECT auction_id * 5, sqrt(auction_id) FROM input