From d42bb7cc4e32c173769bd7da5b9b5eafb510860c Mon Sep 17 00:00:00 2001
From: Dongjoon Hyun <dongjoon@apache.org>
Date: Fri, 11 Nov 2016 13:28:18 -0800
Subject: [PATCH] [SPARK-17982][SQL] SQLBuilder should wrap the generated SQL
with parenthesis for LIMIT
## What changes were proposed in this pull request?
Currently, `SQLBuilder` handles `LIMIT` by always adding `LIMIT` at the end of the generated subSQL. It makes `RuntimeException`s like the following. This PR adds a parenthesis always except `SubqueryAlias` is used together with `LIMIT`.
**Before**
``` scala
scala> sql("CREATE TABLE tbl(id INT)")
scala> sql("CREATE VIEW v1(id2) AS SELECT id FROM tbl LIMIT 2")
java.lang.RuntimeException: Failed to analyze the canonicalized SQL: ...
```
**After**
``` scala
scala> sql("CREATE TABLE tbl(id INT)")
scala> sql("CREATE VIEW v1(id2) AS SELECT id FROM tbl LIMIT 2")
scala> sql("SELECT id2 FROM v1")
res4: org.apache.spark.sql.DataFrame = [id2: int]
```
**Fixed cases in this PR**
The following two cases are the detail query plans having problematic SQL generations.
1. `SELECT * FROM (SELECT id FROM tbl LIMIT 2)`
Please note that **FROM SELECT** part of the generated SQL in the below. When we don't use '()' for limit, this fails.
```scala
# Original logical plan:
Project [id#1]
+- GlobalLimit 2
+- LocalLimit 2
+- Project [id#1]
+- MetastoreRelation default, tbl
# Canonicalized logical plan:
Project [gen_attr_0#1 AS id#4]
+- SubqueryAlias tbl
+- Project [gen_attr_0#1]
+- GlobalLimit 2
+- LocalLimit 2
+- Project [gen_attr_0#1]
+- SubqueryAlias gen_subquery_0
+- Project [id#1 AS gen_attr_0#1]
+- SQLTable default, tbl, [id#1]
# Generated SQL:
SELECT `gen_attr_0` AS `id` FROM (SELECT `gen_attr_0` FROM SELECT `gen_attr_0` FROM (SELECT `id` AS `gen_attr_0` FROM `default`.`tbl`) AS gen_subquery_0 LIMIT 2) AS tbl
```
2. `SELECT * FROM (SELECT id FROM tbl TABLESAMPLE (2 ROWS))`
Please note that **((~~~) AS gen_subquery_0 LIMIT 2)** in the below. When we use '()' for limit on `SubqueryAlias`, this fails.
```scala
# Original logical plan:
Project [id#1]
+- Project [id#1]
+- GlobalLimit 2
+- LocalLimit 2
+- MetastoreRelation default, tbl
# Canonicalized logical plan:
Project [gen_attr_0#1 AS id#4]
+- SubqueryAlias tbl
+- Project [gen_attr_0#1]
+- GlobalLimit 2
+- LocalLimit 2
+- SubqueryAlias gen_subquery_0
+- Project [id#1 AS gen_attr_0#1]
+- SQLTable default, tbl, [id#1]
# Generated SQL:
SELECT `gen_attr_0` AS `id` FROM (SELECT `gen_attr_0` FROM ((SELECT `id` AS `gen_attr_0` FROM `default`.`tbl`) AS gen_subquery_0 LIMIT 2)) AS tbl
```
## How was this patch tested?
Pass the Jenkins test with a newly added test case.
Author: Dongjoon Hyun <dongjoon@apache.org>
Closes #15546 from dongjoon-hyun/SPARK-17982.
---
.../org/apache/spark/sql/catalyst/SQLBuilder.scala | 7 ++++++-
.../test/resources/sqlgen/generate_with_other_1.sql | 2 +-
.../test/resources/sqlgen/generate_with_other_2.sql | 2 +-
sql/hive/src/test/resources/sqlgen/limit.sql | 4 ++++
.../spark/sql/catalyst/LogicalPlanToSQLSuite.scala | 10 ++++++++++
5 files changed, 22 insertions(+), 3 deletions(-)
create mode 100644 sql/hive/src/test/resources/sqlgen/limit.sql
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/catalyst/SQLBuilder.scala b/sql/core/src/main/scala/org/apache/spark/sql/catalyst/SQLBuilder.scala
index 6f821f80cc..380454267e 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/catalyst/SQLBuilder.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/catalyst/SQLBuilder.scala
@@ -138,9 +138,14 @@ class SQLBuilder private (
case g: Generate =>
generateToSQL(g)
- case Limit(limitExpr, child) =>
+ // This prevents a pattern of `((...) AS gen_subquery_0 LIMIT 1)` which does not work.
+ // For example, `SELECT * FROM (SELECT id FROM tbl TABLESAMPLE (2 ROWS))` makes this plan.
+ case Limit(limitExpr, child: SubqueryAlias) =>
s"${toSQL(child)} LIMIT ${limitExpr.sql}"
+ case Limit(limitExpr, child) =>
+ s"(${toSQL(child)} LIMIT ${limitExpr.sql})"
+
case Filter(condition, child) =>
val whereOrHaving = child match {
case _: Aggregate => "HAVING"
diff --git a/sql/hive/src/test/resources/sqlgen/generate_with_other_1.sql b/sql/hive/src/test/resources/sqlgen/generate_with_other_1.sql
index ab444d0c70..0739f8fff5 100644
--- a/sql/hive/src/test/resources/sqlgen/generate_with_other_1.sql
+++ b/sql/hive/src/test/resources/sqlgen/generate_with_other_1.sql
@@ -5,4 +5,4 @@ WHERE id > 2
ORDER BY val, id
LIMIT 5
--------------------------------------------------------------------------------
-SELECT `gen_attr_0` AS `val`, `gen_attr_1` AS `id` FROM (SELECT `gen_attr_0`, `gen_attr_1` FROM (SELECT gen_subquery_0.`gen_attr_2`, gen_subquery_0.`gen_attr_3`, gen_subquery_0.`gen_attr_4`, gen_subquery_0.`gen_attr_1` FROM (SELECT `arr` AS `gen_attr_2`, `arr2` AS `gen_attr_3`, `json` AS `gen_attr_4`, `id` AS `gen_attr_1` FROM `default`.`parquet_t3`) AS gen_subquery_0 WHERE (`gen_attr_1` > CAST(2 AS BIGINT))) AS gen_subquery_1 LATERAL VIEW explode(`gen_attr_2`) gen_subquery_2 AS `gen_attr_0` ORDER BY `gen_attr_0` ASC NULLS FIRST, `gen_attr_1` ASC NULLS FIRST LIMIT 5) AS parquet_t3
+SELECT `gen_attr_0` AS `val`, `gen_attr_1` AS `id` FROM ((SELECT `gen_attr_0`, `gen_attr_1` FROM (SELECT gen_subquery_0.`gen_attr_2`, gen_subquery_0.`gen_attr_3`, gen_subquery_0.`gen_attr_4`, gen_subquery_0.`gen_attr_1` FROM (SELECT `arr` AS `gen_attr_2`, `arr2` AS `gen_attr_3`, `json` AS `gen_attr_4`, `id` AS `gen_attr_1` FROM `default`.`parquet_t3`) AS gen_subquery_0 WHERE (`gen_attr_1` > CAST(2 AS BIGINT))) AS gen_subquery_1 LATERAL VIEW explode(`gen_attr_2`) gen_subquery_2 AS `gen_attr_0` ORDER BY `gen_attr_0` ASC NULLS FIRST, `gen_attr_1` ASC NULLS FIRST LIMIT 5)) AS parquet_t3
diff --git a/sql/hive/src/test/resources/sqlgen/generate_with_other_2.sql b/sql/hive/src/test/resources/sqlgen/generate_with_other_2.sql
index 42a2369f34..c4b344ee23 100644
--- a/sql/hive/src/test/resources/sqlgen/generate_with_other_2.sql
+++ b/sql/hive/src/test/resources/sqlgen/generate_with_other_2.sql
@@ -7,4 +7,4 @@ WHERE val > 2
ORDER BY val, id
LIMIT 5
--------------------------------------------------------------------------------
-SELECT `gen_attr_0` AS `val`, `gen_attr_1` AS `id` FROM (SELECT `gen_attr_0`, `gen_attr_1` FROM (SELECT `arr` AS `gen_attr_4`, `arr2` AS `gen_attr_3`, `json` AS `gen_attr_5`, `id` AS `gen_attr_1` FROM `default`.`parquet_t3`) AS gen_subquery_0 LATERAL VIEW explode(`gen_attr_3`) gen_subquery_2 AS `gen_attr_2` LATERAL VIEW explode(`gen_attr_2`) gen_subquery_3 AS `gen_attr_0` WHERE (`gen_attr_0` > CAST(2 AS BIGINT)) ORDER BY `gen_attr_0` ASC NULLS FIRST, `gen_attr_1` ASC NULLS FIRST LIMIT 5) AS gen_subquery_1
+SELECT `gen_attr_0` AS `val`, `gen_attr_1` AS `id` FROM ((SELECT `gen_attr_0`, `gen_attr_1` FROM (SELECT `arr` AS `gen_attr_4`, `arr2` AS `gen_attr_3`, `json` AS `gen_attr_5`, `id` AS `gen_attr_1` FROM `default`.`parquet_t3`) AS gen_subquery_0 LATERAL VIEW explode(`gen_attr_3`) gen_subquery_2 AS `gen_attr_2` LATERAL VIEW explode(`gen_attr_2`) gen_subquery_3 AS `gen_attr_0` WHERE (`gen_attr_0` > CAST(2 AS BIGINT)) ORDER BY `gen_attr_0` ASC NULLS FIRST, `gen_attr_1` ASC NULLS FIRST LIMIT 5)) AS gen_subquery_1
diff --git a/sql/hive/src/test/resources/sqlgen/limit.sql b/sql/hive/src/test/resources/sqlgen/limit.sql
new file mode 100644
index 0000000000..7a6b060fbf
--- /dev/null
+++ b/sql/hive/src/test/resources/sqlgen/limit.sql
@@ -0,0 +1,4 @@
+-- This file is automatically generated by LogicalPlanToSQLSuite.
+SELECT * FROM (SELECT id FROM tbl LIMIT 2)
+--------------------------------------------------------------------------------
+SELECT `gen_attr_0` AS `id` FROM (SELECT `gen_attr_0` FROM (SELECT `gen_attr_0` FROM (SELECT `id` AS `gen_attr_0`, `name` AS `gen_attr_1` FROM `default`.`tbl`) AS gen_subquery_0 LIMIT 2)) AS tbl
diff --git a/sql/hive/src/test/scala/org/apache/spark/sql/catalyst/LogicalPlanToSQLSuite.scala b/sql/hive/src/test/scala/org/apache/spark/sql/catalyst/LogicalPlanToSQLSuite.scala
index 8696337b9d..557ea44d1c 100644
--- a/sql/hive/src/test/scala/org/apache/spark/sql/catalyst/LogicalPlanToSQLSuite.scala
+++ b/sql/hive/src/test/scala/org/apache/spark/sql/catalyst/LogicalPlanToSQLSuite.scala
@@ -1173,4 +1173,14 @@ class LogicalPlanToSQLSuite extends SQLBuilderTest with SQLTestUtils {
)
}
}
+
+ test("SPARK-17982 - limit") {
+ withTable("tbl") {
+ sql("CREATE TABLE tbl(id INT, name STRING)")
+ checkSQL(
+ "SELECT * FROM (SELECT id FROM tbl LIMIT 2)",
+ "limit"
+ )
+ }
+ }
}
--
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