[SYSTEMDS-1288] Additional meta operator template: MultiAggregate

• Type: Sub-task
• Status: Closed
• Priority: Major
• Resolution: Done
• Fix Version/s: SystemML 0.14
• Component/s: Compiler, Runtime
• Assignee: Matthias Boehm
• Reporter: Matthias Boehm
• Created: 19/Feb/17 06:38
• Updated: 21/Apr/17 04:47
• Resolved: 10/Apr/17 04:29

Description

This task aims to add further codegen templates besides the existing SpoofCellwise, SpoofRowAggregate, and SpoofOuterProduct.

Spoof MultiAggregate: There are quite a number of scenarios where we have expressions like (a) sum(Y == check_min), sum(Y == check_max), or (b) overlapping expressions with large common subexpression, i.e., fusable operations over a shared input with multiple aggregation roots. Since SystemML's compiler/runtime only supports single-output operations (with very few exceptions), it would be beneficial to generate a single fused operator with a combined aggregate output, which is subsequently split via traditional right indexing operations.

Issue Links

• depends upon: SYSTEMDS-1374 Simplify cplan construction algorithm