Github user gatorsmile commented on a diff in the pull request:
https://github.com/apache/spark/pull/17330#discussion_r106795294
--- Diff:
sql/core/src/test/scala/org/apache/spark/sql/CachedTableSuite.scala ---
@@ -655,6 +663,148 @@ class CachedTableSuite extends QueryTest with
SQLTestUtils with SharedSQLContext
}
}
+ test("SPARK-19993 subquery caching") {
+ withTempView("t1", "t2") {
+ Seq(1).toDF("c1").createOrReplaceTempView("t1")
+ Seq(1).toDF("c1").createOrReplaceTempView("t2")
+
+ val ds1 =
+ sql(
+ """
+ |SELECT * FROM t1
+ |WHERE
+ |NOT EXISTS (SELECT * FROM t1)
+ """.stripMargin)
+ assert(getNumInMemoryRelations(ds1) == 0)
+
+ ds1.cache()
+
+ val cachedDs =
+ sql(
+ """
+ |SELECT * FROM t1
+ |WHERE
+ |NOT EXISTS (SELECT * FROM t1)
+ """.stripMargin)
+ assert(getNumInMemoryRelations(cachedDs) == 1)
+
+ // Additional predicate in the subquery plan should cause a cache
miss
+ val cachedMissDs =
+ sql(
+ """
+ |SELECT * FROM t1
+ |WHERE
+ |NOT EXISTS (SELECT * FROM t1 where c1 = 0)
+ """.stripMargin)
+ assert(getNumInMemoryRelations(cachedMissDs) == 0)
+
+ // Simple correlated predicate in subquery
+ val ds2 =
+ sql(
+ """
+ |SELECT * FROM t1
+ |WHERE
+ |t1.c1 in (SELECT t2.c1 FROM t2 where t1.c1 = t2.c1)
+ """.stripMargin)
+ assert(getNumInMemoryRelations(ds2) == 0)
+
+ ds2.cache()
+
+ val cachedDs2 =
+ sql(
+ """
+ |SELECT * FROM t1
+ |WHERE
+ |t1.c1 in (SELECT t2.c1 FROM t2 where t1.c1 = t2.c1)
+ """.stripMargin)
+
+ assert(getNumInMemoryRelations(cachedDs2) == 1)
+
+ spark.catalog.cacheTable("t1")
+ ds1.unpersist()
--- End diff --
How about splitting the test cases to multiple individual ones? The cache
will be cleaned for each test case. This can avoid any extra checking, like
`assert(getNumInMemoryRelations(cachedMissDs) == 0)` or `ds1.unpersist()`
```Scala
override def afterEach(): Unit = {
try {
spark.catalog.clearCache()
} finally {
super.afterEach()
}
}
```
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