Developer Mapping Guide

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Maintain a Stable Sort

When you maintain order in a partitioned mapping, the Data Integration Service does not perform a stable sort. The Data Integration Service maintains the order of the rows based on the sort key. However, if multiple rows have equal values for the sort key, the rows might not appear in the same relative order in the output as they appear in the input.

For example, a mapping enabled for partitioning reads from a sorted flat file source that contains the following data:

Order_ID,Item_ID,Item,Quantity,Price
45,000468,ItemD,5,0.56
45,123456,ItemA,5,3.04
41,456789,ItemB,2,12.02
43,123456,ItemA,3,3.04

The mapping includes a Sorter transformation that specifies Order_ID as the sort key with the direction as descending. When the Data Integration Service uses multiple threads to run the Sorter transformation, it might not maintain the relative order of the rows with the same value for Order_ID. For example, the service might write the rows to a merged target file in the following order:

Order_ID,Item_ID,Item,Quantity,Price
45,123456,ItemA,5,3.04
45,000468,ItemD,5,0.56
43,123456,ItemA,3,3.04
41,456789,ItemB,2,12.02

To maintain a stable sort, disable partitioning for the mapping by setting the

Maximum Parallelism

run-time property for the mapping to 1.

Maintain Order in a Partitioned Mapping

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Table of Contents

Developer Mapping Guide

Developer Mapping Guide

Maintain a Stable Sort

Maintain a Stable Sort