The Sequence Generator transformation has two output fields, NEXTVAL and CURRVAL. In an elastic mapping, the transformation has one output field, NEXTVAL. You cannot edit or delete these fields.

You can connect a Sequence Generator transformation to any transformation. If the mapping contains both fields, you do not need to map both of the output fields. If you do not map one of the output fields, the mapping task ignores the unmapped field.

Use the NEXTVAL field to generate a sequence of numbers based on the Initial Value and Increment By properties.

Map the NEXTVAL field to an input field in a Target transformation or other downstream transformation to generate a sequence of numbers. If you do not configure the Sequence Generator to cycle through the sequence, the NEXTVAL field generates sequence numbers up to the configured End Value.

If you map the NEXTVAL field to multiple transformations, the mapping task generates the same sequence or a unique sequence of numbers for each downstream transformation based on the mapping type and whether incoming fields are disabled.

The following table lists the situations where the Sequence Generator transformation generates the same sequence or a unique sequence of numbers:

Mapping type | Incoming fields are... | Same sequence or unique sequence? |
---|---|---|

Mapping | Not disabled | Same sequence |

Mapping | Disabled | Unique sequence* |

Elastic mapping | - | Same sequence |

* To generate the same sequence of numbers when incoming fields are disabled, you can place an Expression transformation between the Sequence Generator and the transformations to stage the sequence of numbers. |

The CURRVAL field value is the NEXTVAL value plus the Increment By value. For example, if the Initial Value is 1 and Increment By is 1, the mapping task generates the following values for NEXTVAL and CURRVAL:

NEXTVAL | CURRVAL |
---|---|

1 | 2 |

2 | 3 |

3 | 4 |

4 | 5 |

5 | 6 |

Typically, you map the CURRVAL field when the NEXTVAL field is already mapped to a downstream transformation in the map. If you map the CURRVAL field without mapping the NEXTVAL field, the mapping task generates the same number for each row.

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