Github user gatorsmile commented on a diff in the pull request: https://github.com/apache/spark/pull/11846#discussion_r56909402 --- Diff: sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala --- @@ -620,24 +627,26 @@ class Analyzer( } } - /** - * In many dialects of SQL it is valid to sort by attributes that are not present in the SELECT - * clause. This rule detects such queries and adds the required attributes to the original - * projection, so that they will be available during sorting. Another projection is added to - * remove these attributes after sorting. - * - * This rule also resolves the position number in sort references. This support is introduced - * in Spark 2.0. Before Spark 2.0, the integers in Order By has no effect on output sorting. - * - When the sort references are not integer but foldable expressions, ignore them. - * - When spark.sql.orderByOrdinal is set to false, ignore the position numbers too. - */ - object ResolveSortReferences extends Rule[LogicalPlan] { + /** + * In many dialects of SQL it is valid to use ordinal positions in order/sort by and group by + * clauses. This rule is to convert ordinal positions to the corresponding expressions in the + * select list. This support is introduced in Spark 2.0. + * + * - When the sort references or group by expressions are not integer but foldable expressions, + * just ignore them. + * - When spark.sql.orderByOrdinal/spark.sql.groupByOrdinal is set to false, ignore the position + * numbers too. + * + * Before the release of Spark 2.0, the literals in order/sort by and group by clauses + * have no effect on the results. + */ + object ResolveOrdinal extends Rule[LogicalPlan] { --- End diff -- Sure, will do. Thanks!
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