mirror of https://github.com/apache/druid.git
8f90589ce5
* Always return sketches from DS_HLL, DS_THETA, DS_QUANTILES_SKETCH. These aggregation functions are documented as creating sketches. However, they are planned into native aggregators that include finalization logic to convert the sketch to a number of some sort. This creates an inconsistency: the functions sometimes return sketches, and sometimes return numbers, depending on where they lie in the native query plan. This patch changes these SQL aggregators to _never_ finalize, by using the "shouldFinalize" feature of the native aggregators. It already existed for theta sketches. This patch adds the feature for hll and quantiles sketches. As to impact, Druid finalizes aggregators in two cases: - When they appear in the outer level of a query (not a subquery). - When they are used as input to an expression or finalizing-field-access post-aggregator (not any other kind of post-aggregator). With this patch, the functions will no longer be finalized in these cases. The second item is not likely to matter much. The SQL functions all declare return type OTHER, which would be usable as an input to any other function that makes sense and that would be planned into an expression. So, the main effect of this patch is the first item. To provide backwards compatibility with anyone that was depending on the old behavior, the patch adds a "sqlFinalizeOuterSketches" query context parameter that restores the old behavior. Other changes: 1) Move various argument-checking logic from runtime to planning time in DoublesSketchListArgBaseOperatorConversion, by adding an OperandTypeChecker. 2) Add various JsonIgnores to the sketches to simplify their JSON representations. 3) Allow chaining of ExpressionPostAggregators and other PostAggregators in the SQL layer. 4) Avoid unnecessary FieldAccessPostAggregator wrapping in the SQL layer, now that expressions can operate on complex inputs. 5) Adjust return type to thetaSketch (instead of OTHER) in ThetaSketchSetBaseOperatorConversion. * Fix benchmark class. * Fix compilation error. * Fix ThetaSketchSqlAggregatorTest. * Hopefully fix ITAutoCompactionTest. * Adjustment to ITAutoCompactionTest. |
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