Laksh Singla 7c17341caa Return empty result when a group by gets optimized to a timeseries query (#12065) ... Related to #11188 The above mentioned PR allowed timeseries queries to return a default result, when queries of type: select count(*) from table where dim1="_not_present_dim_" were executed. Before the PR, it returned no row, after the PR, it would return a row with value of count(*) as 0 (as expected by SQL standards of different dbs). In Grouping#applyProject, we can sometimes perform optimization of a groupBy query to a timeseries query if possible (when the keys of the groupBy are constants, as generated by automated tools). For example, in select count(*) from table where dim1="_present_dim_" group by "dummy_key", the groupBy clause can be removed. However, in the case when the filter doesn't return anything, i.e. select count(*) from table where dim1="_not_present_dim_" group by "dummy_key", the behavior of general databases would be to return nothing, while druid (due to above change) returns an empty row. This PR aims to fix this divergence of behavior. Example cases: select count(*) from table where dim1="_not_present_dim_" group by "dummy_key". CURRENT: Returns a row with count(*) = 0 EXPECTED: Return no row select 'A', dim1 from foo where m1 = 123123 and dim1 = '_not_present_again_' group by dim1 CURRENT: Returns a row with ('A', 'wat') EXPECTED: Return no row To do this, a boolean droppedDimensionsWhileApplyingProject has been added to Grouping which is true whenever we make changes to the original shape with optimization. Hence if a timeseries query has a grouping with this set to true, we set skipEmptyBuckets=true in the query context (i.e. donot return any row).		2022-01-07 21:53:48 +05:30
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src	Return empty result when a group by gets optimized to a timeseries query (#12065)	2022-01-07 21:53:48 +05:30
pom.xml	Add druid.sql.approxCountDistinct.function property. (#11181)	2021-10-25 12:16:21 -07:00