combined oparators

[agpt]

Hi All,

can anybody tell me what are combined operators. Normally they are being disabled using APT_DISABLE_COMBINATION. What exactly it does is not by disabling the combined operators.

[ray.wurlod]

Operator combination is the decision made at run time, when the score is being composed, to execute multiple adjacent operators that share the same parallelism and partitioning specifications into one process rather than using a separate process for each operator. The combined operator is called APT_CombinedOperatorController and the score will reveal the operators that have been combined.

Despite the generally laudable goal of reducing total processes, operator combination is as aggressive as possible, which can lead to too few processes or, to put it another way, too much resource demand in a single process. Every stage, therefore, can be made not combinable through its properties.

The other "problem" for operator combination is that all errors and warnings are reported as being from APT_CombinedOperatorController, so you don't get information about which operator actually threw the error. Therefore, while diagnosing, disabling operator combination is usually a valuable technique.

[myukassign]

It's very very very useful information...... Mainly debugging help you mentioned....

Thanks....