Ted Dunning created DRILL-3462: ---------------------------------- Summary: There appears to be no way to have complex intermediate state Key: DRILL-3462 URL: https://issues.apache.org/jira/browse/DRILL-3462 Project: Apache Drill Issue Type: Bug Reporter: Ted Dunning
After spending several frustrating days on the problem (see also DRILL-3461), it appears that there is no viable idiom for building an aggregator that has internal state that is anything more than a scalar. What is needed is: 1) The ability to allocate a Repeated* type for use in a Workspace variables. Currently, new works to get the basic structure, but there is no good way to allocate the corresponding vector. 2) The ability to use and to allocate a ComplexWriter in the Workspace variables. 3) The ability to write a UDAF that supports multi-phase aggregation. It would be just fine if I simply have to write a combine method on my UDAF class. I don't think that there is any way to infer such a combiner from the parameters and workspace variables. An alternative API would be to have a form of the output function that is given an Iterable<OutputClass>, but that is probably much less efficient than simply having a combine method that is called repeatedly. -- This message was sent by Atlassian JIRA (v6.3.4#6332)