Common Sub-Expression optimization

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The problem One common pattern we see in some analytical workloads is the repeated use of the same, often times expensive expression. Look at the following query plan for example: The expression JSON_PARSE(features) is used 6 times, and casted to different ROW structures for further processing. Traditionally, Presto would just execute the expression 6 times,…

Using OptimizedTypedSet to Improve Map and Array Functions

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Function evaluation is a big part of projection CPU cost. Recently we optimized a set of functions that use TypedSet, e.g. map_concat, array_union, array_intersect, and array_except. By introducing a new OptimizedTypeSet, the above functions saw improvements in several dimensions: Furthermore, OptimizedTypeSet resolves the long standing issue of throwing EXCEEDED_FUNCTION_MEMORY_LIMIT for large incoming blocks: “The input…