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Wes McKinney commented on ARROW-3978: ------------------------------------- [~bkietz] [~michalno] seems like this could be supported pretty soon using the new hash table machinery? > [C++] Implement hashing, dictionary-encoding for StructArray > ------------------------------------------------------------ > > Key: ARROW-3978 > URL: https://issues.apache.org/jira/browse/ARROW-3978 > Project: Apache Arrow > Issue Type: New Feature > Components: C++ > Reporter: Wes McKinney > Priority: Major > Labels: query-engine > > This is a central requirement for hash-aggregations such as > {code} > SELECT AGG_FUNCTION(expr) > FROM table > GROUP BY expr1, expr2, ... > {code} > The materialized keys in the GROUP BY section form a struct, which can be > incrementally hashed to produce dictionary codes suitable for computing > aggregates or any other purpose. > There are a few subtasks related to this, such as efficiently constructing a > record (that can be hashed quickly) to identify each "row" in the struct. > Maybe we should start with that first -- This message was sent by Atlassian Jira (v8.3.4#803005)