Trigger types in Sequencer Job

While designing Sequencer jobs when we are using any Sequencer Stage ( Job activity, Command activity or others ), it has a tab named 'trigger' which actually determine the actions that occur when the activity runs. Each activity can output different trigger types. 

Three types of triggers are available, with some types having subtypes.

Conditional

A conditional trigger runs the target activity if the source activity fulfills the specified condition. The condition is defined by an expression, and can be one of the following types:

Execution Steps in Transformer Stage - Explanation

 You can access Part1 Here -  Execution Steps in Transformer Stage

Certain constructs are inefficient if they are included in output column derivations, because they are evaluated once for every output column that uses them. The following examples describe these constructs:

The same part of an expression is used in multiple column derivations.

For example, if you want to use the same substring of an input column in multiple columns in output links, you might use the following test in a number of output columns derivations:

IF (DSLINK1.col1[1,3] = "001") THEN ...

In this case, the evaluation of the substring of DSLINK1.col1[1,3] is repeated for each column that uses it. The evaluation can be made more efficient by moving the substring calculation into a stage variable. The substring is then evaluated once for every input row. This example has thus stage variable definition for StageVar1:

Execution Steps in Transformer Stage

I've been asked this questions so many times in interviews and by different practitioner also that What are the data processing steps when datastage is processing transformer, So here I tried to compiled. Have a look -


To write efficient Transformer stage derivations, it helps to understand what items get evaluated and when.