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Remus Rusanu commented on CALCITE-1790: --------------------------------------- I created CALCITE-1794 > Simplify CASE P1 THEN <boolean> P@ THEN <booleans> ... ELSE TRUE/FALSE > ----------------------------------------------------------------------- > > Key: CALCITE-1790 > URL: https://issues.apache.org/jira/browse/CALCITE-1790 > Project: Calcite > Issue Type: Improvement > Components: core > Reporter: Remus Rusanu > Assignee: Remus Rusanu > Priority: Minor > > In HIVE-14431 [~jcamachorodriguez] proposed a simplification for CASE when > all branches are not nullable boolean expression into an alternative > AND/OR/NOT based expression. This allows for more aggressive reductions and > split/push-down on the whole. Meantime the simplifier code migrated to > Calcite so I'm reviving this here. > The proposed simplification is: > {code} > CASE > WHEN p1 THEN ex1 > WHEN p2 THEN ex2 > ... > WHEN pn THEN exn > ELSE TRUE/FALSE > END > {code} > to be transformed into: > {code} > (p1 AND ex1) > OR (not(p1) AND p2 AND x2) > ... > OR (not(p1) AND not(p2) ... AND not(pn-1) AND Pn AND exn) > [OR (not(p1) AND not(p2) ... AND not(pn))] > {code} > The last OR is depending on the ELSE branch being TRUE/FALSE. -- This message was sent by Atlassian JIRA (v6.3.15#6346)