Remus Rusanu created CALCITE-1790:
-------------------------------------
Summary: 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 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] (not(p1) AND not(p2) ... AND not(pn))
{code}
The last OR is negated depending on the ELSE branch being TRUE/FALSE.
--
This message was sent by Atlassian JIRA
(v6.3.15#6346)
