Output Type

Note that each transform has either an Aggregate or Non-Aggregate output type.

Whether an output is Non-Aggregate or Aggregate depends on whether the output value relies on a single record or several records. It is Non-Aggregate if the result is strictly from a single record, while it is Aggregate if it is from several records. For example, the value of Count transform of circulation id will increase by 1 whenever a record is found. So the output is Aggregate. The output of Max transform of checkout date is technically not aggregated, but there may be several records involved before the highest value is determined.

When used as filters, non-aggregate and aggregate types correspond to Base and Aggregate filters respectively. To see the difference between a base filter and an aggregate filter, imagine that you are creating a report to find out the popular items that were circulated more than 3 times last month. This would require a base filter to specify the month of interest and an aggregate filter on the count of circulation record on each item.

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