cloud-fan commented on a change in pull request #34053:
URL: https://github.com/apache/spark/pull/34053#discussion_r715020883
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File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/Optimizer.scala
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@@ -2122,6 +2125,68 @@ object RewriteIntersectAll extends Rule[LogicalPlan] {
}
}
+/**
+ * Replaces logical [[AsOfJoin]] operator using a combination of Join and
Aggregate operator.
+ *
+ * Input Pseudo-Query:
+ * {{{
+ * SELECT * FROM left ASOF JOIN right ON (condition, as_of on(left.t,
right.t), tolerance)
+ * }}}
+ *
+ * Rewritten Query:
+ * {{{
+ * SELECT left.*, __right__.*
+ * FROM (
+ * SELECT
+ * left.*,
+ * (
+ * SELECT MIN_BY(STRUCT(right.*), left.t - right.t)
+ * FROM right
+ * WHERE condition AND left.t >= right.t AND right.t >=
left.t - tolerance
+ * ) as __right__
+ * FROM left
+ * )
+ * }}}
+ */
+object RewriteAsOfJoin extends Rule[LogicalPlan] {
Review comment:
nit: move it to a new file?
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