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The cluster property is used to assist MettleCI’s resource management when using high volumes of test data. Setting a Cluster Key will prompt MettleCI to split the actual output and expected output using multiple, smaller subsets (based on the supplied keys) before the data is compared. Data is split such that each subset will only contain records that have the same values for all columns that make up the Cluster Key. In general, cluster keys should only be used when necessary rather then being specified by default. Read more about the using the cluster property in High Volume Unit Tests.
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