peter-toth commented on a change in pull request #23531: [SPARK-24497][SQL]
Support recursive SQL query
URL: https://github.com/apache/spark/pull/23531#discussion_r252286309
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/analysis/Analyzer.scala
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@@ -202,19 +203,58 @@ class Analyzer(
Batch("Subquery", Once,
UpdateOuterReferences),
Batch("Cleanup", fixedPoint,
- CleanupAliases)
+ CleanupAliases),
+ Batch("Recursion", Once,
+ CheckRecursionConstraints)
)
+ object ResolveRecursiveReferneces extends Rule[LogicalPlan] {
Review comment:
I remember now. The thing is that when we have nested recursion and the
outer recursive reference is in the anchor of the inner recursion like this:
```
-- recursion nested into recursion 2
WITH RECURSIVE t AS (
WITH RECURSIVE s AS (
SELECT j, 1 AS i FROM t
UNION ALL
SELECT j, i + 1 FROM s WHERE i < 3
)
VALUES (1) as t(j)
UNION ALL
SELECT j + 1 FROM s WHERE j < 3
)
SELECT * FROM t;
```
analyzing the inner will not resolve it's anchor and so we can't place
resolved `RecursiveReference s` immediately into the plan.
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