Operators and Players

Pravenai · Post by **Pravenai** » Sun May 29, 2011 11:53 pm

What is the difference between operators and players?

ray.wurlod · Post by **ray.wurlod** » Mon May 30, 2011 12:41 am

An operator is an executable piece of code - an object of the APT_OPERATOR class. A player is the process that executes that code.

jhmckeever · Post by **jhmckeever** » Mon May 30, 2011 12:46 am

Operators are logical representations of individual executable components between which your data flows. A script which describes your job's operators and the flows between them is called the OSH script, and is what your parallel DataStage job gets compiled to.

How multiple instances of each operator are executed across a multi-processor architecture (according to your node configuration) is the job of the SCORE which describes how this is achieved using Conductor, Section Leader, and Player processes.

Players are described within the context of the score here:
viewtopic.php?t=125205&highlight=players

J.

PS. I'm sure Ray'll be along in a few minutes with a much more concise explanation!

jhmckeever · Post by **jhmckeever** » Mon May 30, 2011 12:47 am

Ha - He beat me to it!

Pravenai · Post by **Pravenai** » Mon May 30, 2011 1:03 am

ray.wurlod wrote:An operator is an executable piece of code - an object of the APT_OPERATOR class. A player is the process that executes that code. ...

Is it true that a player is created for every stage on every node? If yes does that mean the number of operators created in a job (including the instances) will be equal to the number of players (unless no operators are combined into one)?

ray.wurlod · Post by **ray.wurlod** » Mon May 30, 2011 5:06 am

It's not necessarily true. Even after you exclude operator combination, sometimes there are more operators then stages. For example, overwriting a Data Set creates two operators (called a "composite operator"), one to delete the Data Set, the other to copy data into it. A normal lookup generates a composite operator made up of LUT_CreateOp to create the lookup table in memory and LUT_ProcessOp to perform the actual lookups. Finally, when the score is composed, other operators - such as tsort and buffer operators - may be inserted while some stages - such as Copy and Modify stages - may end up generating no operator at all.