pratham76 commented on code in PR #58656:
URL: https://github.com/apache/spark/pull/58656#discussion_r4356971327
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sql/core/src/test/scala/org/apache/spark/sql/SubquerySuite.scala:
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@@ -3227,4 +3224,625 @@ class SubquerySuite extends SharedSparkSession
}
}
}
+
+ /**
+ * Checks the result of `query`, that every node of its optimized plan can
produce the attributes
+ * it references, and that the existence join a nested subquery was
rewritten into sits on the
+ * subquery side of the semi/anti join.
+ *
+ * The plan checks are what SPARK-59351 is about: an existence join whose
condition references an
+ * attribute produced by neither of its children can still return the right
answer when the
+ * nested relation is empty at runtime, because the invalid condition is
then never bound, and a
+ * rewrite that placed the join on the other side would return the right
answer here too. Note
+ * that missingInput cannot see a subquery expression that survives in a
condition, since
+ * QueryPlan.references folds only the outer attributes of one and collect
does not walk its
+ * plan, so it is not a substitute for asserting the shape.
+ */
+ private def checkAnswerAndPlan(
+ query: String,
+ expected: Seq[Row],
+ existenceJoinOnSubqueryPlan: Boolean = true): Unit = {
+ val df = sql(query)
+ val plan = df.queryExecution.optimizedPlan
+ val invalidNodes = plan.collect { case p if p.missingInput.nonEmpty => p }
+ assert(invalidNodes.isEmpty,
+ s"""Plan nodes reference non-reachable attributes:
+ |${invalidNodes.mkString("\n")}
+ |$plan""".stripMargin)
+ if (existenceJoinOnSubqueryPlan) {
+ val semiOrAnti = plan.collectFirst {
+ case j: Join if j.joinType == LeftSemi || j.joinType == LeftAnti => j
+ }
+ assert(semiOrAnti.nonEmpty, s"expected a semi or anti join in\n$plan")
+ val existenceJoins = plan.collect {
+ case j: Join if j.joinType.isInstanceOf[ExistenceJoin] => j
+ }
+ assert(existenceJoins.nonEmpty, s"expected an existence join in\n$plan")
+ // The existence join must be under the right side of the semi/anti
join, which is the
+ // subquery plan, and not under its left side, which is the outer plan.
+ assert(existenceJoins.forall(j =>
semiOrAnti.get.right.exists(_.fastEquals(j))),
+ s"the existence join must sit on the subquery side in\n$plan")
+ }
+ checkAnswer(df, expected)
+ }
+
+ test("SPARK-59351: nested subquery referencing the inner query becomes an
existence join") {
+ // SPARK-45580 covers the case where the nested subquery references the
outer query, in which
+ // case its existence join is built on top of the outer plan. Here the
nested subquery
+ // references the query it is nested in, so the existence join has to be
built on top of the
+ // subquery plan instead.
+ withTempView("t1", "t2", "t3", "t3n", "t4", "t5") {
+ Seq((1), (2), (3), (7),
(9)).toDF("a").persist().createOrReplaceTempView("t1")
+ Seq((1), (8), (9)).toDF("c1").persist().createOrReplaceTempView("t2")
+ // t3 shares a value with t2, t5 does not, so the nested subquery
decides the answer below.
+ Seq((3), (9)).toDF("col1").persist().createOrReplaceTempView("t3")
+ Seq((3), (7)).toDF("col1").persist().createOrReplaceTempView("t5")
+ Seq(Some(3), Some(9),
None).toDF("col1").persist().createOrReplaceTempView("t3n")
+ // A correlated nested IN over t4 is false for every c1 in t2, while the
same IN without its
+ // correlated predicate is true for 1 and 9, so the correlation decides
the answer below.
+ Seq((1, 9), (9, 1)).toDF("col1",
"k").persist().createOrReplaceTempView("t4")
+
+ // EXISTS rewritten as a left semi join. The correlated predicate is a
disjunction, so it
+ // is pulled up as a whole and carries the nested IN-subquery, which
references c1, out of
+ // the subquery plan.
+ val query1 =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE EXISTS (
+ | SELECT c1
+ | FROM t2
+ | WHERE a = c1
+ | OR c1 IN (SELECT col1 FROM t3)
+ |)""".stripMargin
+ checkAnswerAndPlan(query1, Row(1) :: Row(2) :: Row(3) :: Row(7) ::
Row(9) :: Nil)
+
+ // Same over t5, which shares no value with t2, so the nested IN is
false for every c1 and
+ // only the correlated predicate can hold: a mistake making it true
would return every row.
+ val query2 =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE EXISTS (
+ | SELECT c1
+ | FROM t2
+ | WHERE a = c1
+ | OR c1 IN (SELECT col1 FROM t5)
+ |)""".stripMargin
+ checkAnswerAndPlan(query2, Row(1) :: Row(9) :: Nil)
+
+ // NOT EXISTS rewritten as a left anti join.
+ val query3 =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE NOT EXISTS (
+ | SELECT c1
+ | FROM t2
+ | WHERE a = c1
+ | OR c1 IN (SELECT col1 FROM t5)
+ |)""".stripMargin
+ checkAnswerAndPlan(query3, Row(2) :: Row(3) :: Row(7) :: Nil)
+
+ // IN-subquery rewritten as a left semi join. The hoisted predicate is a
> c1 rather than
+ // the key equality a = c1, so the answer is a IN (t2 INTERSECT t3) and
depends on the
+ // nested subquery: dropping it would leave no row at all.
+ val query4 =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE a IN (
+ | SELECT c1
+ | FROM t2
+ | WHERE a > c1
+ | OR c1 IN (SELECT col1 FROM t3)
+ |)""".stripMargin
+ checkAnswerAndPlan(query4, Row(9) :: Nil)
+
+ // NOT IN-subquery rewritten as a null-aware left anti join, with a
nested EXISTS. Only the
+ // nested EXISTS keeps 9 out of the answer, as a > c1 alone does not
hold for it.
+ val query5 =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE a NOT IN (
+ | SELECT c1
+ | FROM t2
+ | WHERE a > c1
+ | OR EXISTS (SELECT 1 FROM t3 WHERE col1 = c1)
+ |)""".stripMargin
+ checkAnswerAndPlan(query5, Row(1) :: Row(2) :: Row(3) :: Row(7) :: Nil)
+
+ // A nested NOT IN-subquery keeps its null-aware semantics: c1 NOT IN
(3, 9, NULL) is never
+ // true, so only the correlated predicate can be satisfied. Compare with
query7, where the
+ // same NOT IN over a relation without NULL holds for c1 = 1 and returns
every row.
+ val query6 =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE EXISTS (
+ | SELECT c1
+ | FROM t2
+ | WHERE a = c1
+ | OR c1 NOT IN (SELECT col1 FROM t3n)
+ |)""".stripMargin
+ checkAnswerAndPlan(query6, Row(1) :: Row(9) :: Nil)
+
+ val query7 =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE EXISTS (
+ | SELECT c1
+ | FROM t2
+ | WHERE a = c1
+ | OR c1 NOT IN (SELECT col1 FROM t3)
+ |)""".stripMargin
+ checkAnswerAndPlan(query7, Row(1) :: Row(2) :: Row(3) :: Row(7) ::
Row(9) :: Nil)
+
+ // A nested subquery correlated to the query it is nested in, on a
column it does not
+ // project, so its correlated predicate changes the answer: without it
the nested IN would
+ // hold for c1 = 1 and row 1 would be returned as well.
+ val query8 =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE EXISTS (
+ | SELECT c1
+ | FROM t2
+ | WHERE a > c1
+ | OR c1 IN (SELECT col1 FROM t4 WHERE k = c1)
+ |)""".stripMargin
+ checkAnswerAndPlan(query8, Row(2) :: Row(3) :: Row(7) :: Row(9) :: Nil)
+ }
+ }
+
+ test("SPARK-59351: nested subquery referencing both the outer and the inner
query") {
+ withTempView("t1", "t2", "t3", "t4") {
+ Seq((1), (2), (3)).toDF("a").persist().createOrReplaceTempView("t1")
+ Seq((1), (8), (9)).toDF("c1").persist().createOrReplaceTempView("t2")
+ Seq((3), (9)).toDF("col1").persist().createOrReplaceTempView("t3")
+ // Correlated, this is false for every c1 in t2; without its correlated
predicate it holds
+ // for 1 and 9, so the correlation decides the answer below.
+ Seq((1, 9), (9, 1)).toDF("col1",
"k").persist().createOrReplaceTempView("t4")
+
+ // The nested subquery references the outer query through its values and
the inner query
+ // through its own correlated predicate, so it can be rewritten into an
existence join on
+ // neither side and stays in the join condition. Planning it there as an
in-subquery filter
+ // drops its correlated predicate col1 = c1, which is why it is rejected
rather than left.
+ // These rows do not distinguish the two forms; the EXISTS form of this
shape does, and
+ // returned an extra row before the rejection was added.
+ //
+ // NOT IN is the outer predicate on purpose: its rewrite returns a bare
Join, which
+ // RewritePredicateSubquery does not offer to its own handling of
predicate subqueries in
+ // join conditions, so this rejection is the only one that can fire and
the assertion below
+ // pins it. With EXISTS the rewrite returns a Project over the join,
which that handling
+ // reaches under the default configuration and rejects with
+ // UNSUPPORTED_CORRELATED_EXPRESSION_IN_JOIN_CONDITION instead, so the
query would still
+ // fail but on a different condition than the one asserted here.
+ val correlated =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE a NOT IN (
+ | SELECT c1
+ | FROM t2
+ | WHERE a = c1
+ | OR a IN (SELECT col1 FROM t3 WHERE col1 = c1)
+ |)""".stripMargin
+ Seq("true", "false").foreach { decorrelateInJoinCondition =>
+
withSQLConf(SQLConf.DECORRELATE_PREDICATE_SUBQUERIES_IN_JOIN_CONDITION.key ->
+ decorrelateInJoinCondition) {
+ val e = intercept[AnalysisException](sql(correlated).collect())
+ assert(e.getCondition == "UNSUPPORTED_SUBQUERY_EXPRESSION_CATEGORY."
+
+ "NESTED_SUBQUERY_REFERENCING_OUTER_AND_INNER_QUERY")
+ // The message must name the subquery that was rejected.
+ val reported = e.getMessageParameters.get("subqueryExpression")
+ assert(reported.contains("IN") && reported.contains("listquery"),
+ s"unexpected subqueryExpression: $reported")
+ }
+ }
+
+ // A correlated predicate that BooleanSimplification has eliminated:
+ // PullupCorrelatedPredicates retains c1 as an outer attribute of the
nested subquery for
+ // idempotency, but the subquery
+ // no longer reads it, so there is no condition to lose. It must still
be rewritten against
+ // the outer plan, which is the only plan it effectively references,
rather than be treated
+ // as referencing the subquery plan and rejected.
+ val simplifiedAwayCorrelation =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE EXISTS (
+ | SELECT 1
+ | FROM t2
+ | WHERE a = c1
+ | OR a IN (SELECT col1 FROM t3 WHERE false AND col1 = c1)
+ |)""".stripMargin
+ Seq("true", "false").foreach { decorrelateInJoinCondition =>
+
withSQLConf(SQLConf.DECORRELATE_PREDICATE_SUBQUERIES_IN_JOIN_CONDITION.key ->
+ decorrelateInJoinCondition) {
+ checkAnswer(sql(simplifiedAwayCorrelation), Row(1) :: Nil)
+ }
+ }
+
+ // A subquery that stays in the join condition stays there whole, since
the rewrite does
+ // not descend into one it declines, so a correlated subquery below it
is left as well.
+ // Its own references make it look routable, being owned by the subquery
plan, but
+ // nothing reaches it and planning a list query as an in-subquery filter
drops the
+ // predicate the pull-up hoisted into it. The enclosing subquery is
rejected for
+ // carrying it: PostgreSQL and DuckDB return 1 and 3 here, and losing
the correlation
+ // returns 2 as well.
+ val carriedCorrelation =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE EXISTS (
+ | SELECT 1
+ | FROM t2
+ | WHERE a = c1
+ | OR (a + (CASE WHEN c1 IN (SELECT col1 FROM t4 WHERE k = c1) THEN
1 ELSE 0 END))
+ | IN (SELECT col1 FROM t3)
+ |)""".stripMargin
+ Seq("true", "false").foreach { decorrelateInJoinCondition =>
+
withSQLConf(SQLConf.DECORRELATE_PREDICATE_SUBQUERIES_IN_JOIN_CONDITION.key ->
+ decorrelateInJoinCondition) {
+ val e =
intercept[AnalysisException](sql(carriedCorrelation).collect())
+ assert(e.getCondition == "UNSUPPORTED_SUBQUERY_EXPRESSION_CATEGORY."
+
+ "NESTED_SUBQUERY_REFERENCING_OUTER_AND_INNER_QUERY")
+ }
+ }
+
+ // An uncorrelated nested subquery referencing both queries has no
correlated predicate to
+ // lose, so it stays in the join condition and is planned as an
in-subquery filter. The
+ // configuration is disabled because the rewrite of predicate subqueries
in join conditions
+ // rejects a subquery referencing both join inputs, which is what this
one becomes.
+ val uncorrelated =
+ """
+ |SELECT *
+ |FROM t1
+ |WHERE EXISTS (
+ | SELECT 1
+ | FROM t2
+ | WHERE a = c1
+ | OR (a + c1) IN (SELECT col1 FROM t3)
+ |)""".stripMargin
+ withSQLConf(
+ SQLConf.DECORRELATE_PREDICATE_SUBQUERIES_IN_JOIN_CONDITION.key ->
"false") {
+ // No existence join here: this subquery stays in the join condition,
which is the
+ // point of the case, so only the result and the reachability of the
plan are
+ // checked.
+ checkAnswerAndPlan(uncorrelated, Row(1) :: Row(2) :: Nil,
+ existenceJoinOnSubqueryPlan = false)
+ }
+ }
+ }
+
+ test("SPARK-59351: existential subquery carried by a rewritten nested
subquery") {
+ // The nested IN over t4 is owned by the subquery plan, so it is rewritten
into an existence
+ // join and the condition PullupCorrelatedPredicates hoisted into it is
grafted onto that
+ // join. That condition carries a third-level IN correlated to t4, which
references neither
+ // the outer nor the subquery plan and so is routed by neither of the
guards above. It has to
+ // be rewritten against the inputs of the join just built: left in place,
PlanSubqueries plans
+ // it as an in-subquery filter and drops its own correlated predicate col1
= k, which returns
+ // every row of t1 instead of the one row where the correlation holds.
+ withTempView("t1", "t2", "t4", "t5") {
+ Seq(1, 2, 3).toDF("a").persist().createOrReplaceTempView("t1")
+ Seq(1, 8, 9).toDF("c1").persist().createOrReplaceTempView("t2")
+ // No k equals any c1, so only the third-level IN can satisfy the
hoisted disjunction, and
+ // its correlated predicate col1 = k is false for every row of t4:
dropping it makes the
+ // level-2 IN hold for c1 = 1 and returns 1, 2 and 3.
+ Seq((1, 100), (9, 7)).toDF("col1",
"k").persist().createOrReplaceTempView("t4")
+ Seq(1).toDF("col1").persist().createOrReplaceTempView("t5")
+ val query =
+ """SELECT * FROM t1 WHERE EXISTS (
+ | SELECT 1 FROM t2
+ | WHERE a = c1
+ | OR c1 IN (SELECT col1 FROM t4
+ | WHERE k = c1 OR col1 IN (SELECT col1 FROM t5 WHERE col1
= k)))""".stripMargin
+ // The routing must not depend on the rewrite of predicate subqueries in
join conditions,
+ // which is what used to make these two configurations disagree: it
reached the grafted
+ // condition only when enabled.
+ Seq("true", "false").foreach { decorrelateInJoinCondition =>
+
withSQLConf(SQLConf.DECORRELATE_PREDICATE_SUBQUERIES_IN_JOIN_CONDITION.key ->
+ decorrelateInJoinCondition) {
+ checkAnswerAndPlan(query, Row(1) :: Nil)
+ }
+ }
+ }
+ }
+
+ test("SPARK-59351: NOT IN keeps an uncorrelated three-valued residual") {
+ // The NOT IN rewrite returns a bare Join, which this rule does not offer
to its own handling
+ // of predicate subqueries in join conditions, so an uncorrelated nested
IN left in the
+ // anti-join condition stays there and InSubqueryExec evaluates it
three-valued. No existence
+ // join is built for it and it has no hoisted condition to lose, so it
must not be rejected:
+ // these queries returned the standard SQL answer before SPARK-59351 and
must keep doing so.
+ withTempView("t1", "t2", "t3n", "t4n") {
+ Seq(1, 2, 3).toDF("a").persist().createOrReplaceTempView("t1")
+ Seq(1, 8, 9).toDF("c1").persist().createOrReplaceTempView("t2")
+ // The NULL matches no c1, so c1 IN (SELECT col1 FROM t3n) is unknown
for every row of t2.
+ Seq(Some(3), None).toDF("col1").persist().createOrReplaceTempView("t3n")
+ // Nullable col1 again, but correlated through k = c1.
+ Seq((Some(3), 1), (None, 8)).toDF("col1",
"k").persist().createOrReplaceTempView("t4n")
+
+ Seq(
+ "(c1 IN (SELECT col1 FROM t3n)) <=> false",
+ "(c1 IN (SELECT col1 FROM t3n)) IS NULL",
+ "COALESCE(c1 IN (SELECT col1 FROM t3n), true)",
+ "(c1 NOT IN (SELECT col1 FROM t3n)) <=> false").foreach { predicate =>
+ // Every such predicate is FALSE for every row of t2, so the subquery
reduces to a = c1
+ // and only 2 and 3 survive the NOT IN. Rejecting instead, or
rewriting the nested IN into
+ // a two-valued exists, would change this.
+ checkAnswer(
+ sql(s"SELECT * FROM t1 WHERE a NOT IN (SELECT c1 FROM t2 WHERE a =
c1 OR $predicate)"),
Review Comment:
Both points are right, and the comment was worse than you describe: I wrote
that every predicate is FALSE for every row of t2, and two of the four are TRUE
there, since `unknown IS NULL` is TRUE and `COALESCE(unknown, true)` is TRUE.
Rebuilt on your suggestion, with `c1 > a` instead of the key equality, which
makes every case discriminate and splits them into two groups by what unknown
does:
| predicate | three-valued (asserted) | two-valued |
|---|---|---|
| `(c1 IN (...)) <=> false` | `1, 2, 3` | `2, 3` |
| `(c1 NOT IN (...)) <=> false` | `1, 2, 3` | `2, 3` |
| `(c1 IN (...)) IS NULL` | `2, 3` | `1, 2, 3` |
| `COALESCE(c1 IN (...), true)` | `2, 3` | `1, 2, 3` |
All four asserted answers match DuckDB. Checked that they discriminate
against a two-valued rewrite specifically, not only against a rejection:
letting `canRewrite` consume the residual while keeping it out of the rejection
makes the test fail on the answers.
The truth-only case at the end now uses `checkAnswerAndPlan`, so "rewritten,
not kept" is actually checked.
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