Aggregates#
The filter unit also computes various summaries or aggregates of the data, which are returned in fields in the job structure. The meaning of these values varies slightly depending on whether the output is nominally a bit vector or an array:
Field |
Bit Vector Meaning |
Array Meaning |
---|---|---|
Index of first 1-bit in output |
Min value over output |
|
Index of last 1-bit in output |
Max value over output |
|
Number of 1-bits in output |
Sum of output values |
Considering a bit vector output, e.g., doing a scan operation, these values can tell the software how sparse the result is, as well as where one should start and end walking through the results to find all the 1’s.
Note
The meaning of the aggregates is not changed by the output modification (see Output Modification). If the output is nominally a bit vector, and due to the output modification, the output actually contains 32-bit indices, the aggregates still reflect the bit vector values.