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Aman Sinha updated DRILL-7187: ------------------------------ Reviewer: Gautam Parai > Improve selectivity estimates for range predicates when using histogram > ----------------------------------------------------------------------- > > Key: DRILL-7187 > URL: https://issues.apache.org/jira/browse/DRILL-7187 > Project: Apache Drill > Issue Type: Bug > Reporter: Aman Sinha > Assignee: Aman Sinha > Priority: Major > Labels: ready-to-commit > Fix For: 1.17.0 > > > 2 types of selectivity estimation improvements need to be done: > 1. For range predicates on the same column, we need to collect all such > predicates in 1 group and do a histogram lookup for them together. > For instance: > {noformat} > WHERE a > 10 AND b < 20 AND c = 100 AND a <= 50 AND b < 50 > {noformat} > Currently, the Drill behavior is to treat each of the conjuncts > independently and multiply the individual selectivities. However, that will > not give the accurate estimates. Here, we want to group the predicates on 'a' > together and do a single lookup. Similarly for 'b'. > 2. NULLs are not maintained by the histogram but when doing the selectivity > calculations, the histogram should use the totalRowCount as the denominator > rather than the non-null count. -- This message was sent by Atlassian JIRA (v7.6.3#76005)