Github user cloud-fan commented on a diff in the pull request:
https://github.com/apache/spark/pull/17546#discussion_r110569876
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/CostBasedJoinReorder.scala
---
@@ -327,3 +345,104 @@ object JoinReorderDP extends PredicateHelper with
Logging {
case class Cost(card: BigInt, size: BigInt) {
def +(other: Cost): Cost = Cost(this.card + other.card, this.size +
other.size)
}
+
+/**
+ * Implements optional filters to reduce the search space for join
enumeration.
+ *
+ * 1) Star-join filters: Plan star-joins together since they are assumed
+ * to have an optimal execution based on their RI relationship.
+ * 2) Cartesian products: Defer their planning later in the graph to avoid
+ * large intermediate results (expanding joins, in general).
+ * 3) Composite inners: Don't generate "bushy tree" plans to avoid
materializing
+ * intermediate results.
+ *
+ * Filters (2) and (3) are not implemented.
+ */
+case class JoinReorderDPFilters(conf: SQLConf) extends PredicateHelper {
+ /**
+ * Builds join graph information to be used by the filtering strategies.
+ * Currently, it builds the sets of star/non-star joins.
+ * It can be extended with the sets of connected/unconnected joins, which
+ * can be used to filter Cartesian products.
+ */
+ def buildJoinGraphInfo(
--- End diff --
please add parameter doc, especially for `planIndex`, what does it mean?
---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---
---------------------------------------------------------------------
To unsubscribe, e-mail: reviews-unsubscr...@spark.apache.org
For additional commands, e-mail: reviews-h...@spark.apache.org
