[SPARK-31234][SQL][2.4] ResetCommand should not affect static SQL Configuration

docs/sql-migration-guide-upgrade.md

@@ -7,7 +7,11 @@ displayTitle: Spark SQL Upgrading Guide
 * Table of contents
 {:toc}
 
-## Upgrading from Spark SQL 2.4 to 2.4.5
+## Upgrading from Spark SQL 2.4.5 to 2.4.6
+
+ - In Spark 2.4.6, the `RESET` command does not reset the static SQL configuration values to the default. It only clears the runtime SQL configuration values.
+
+## Upgrading from Spark SQL 2.4.4 to 2.4.5
 
  - Starting from 2.4.5, SQL configurations are effective also when a Dataset is converted to an RDD and its
    plan is executed due to action on the derived RDD. The previous behavior can be restored setting

sql/core/src/main/scala/org/apache/spark/sql/execution/command/SetCommand.scala

@@ -164,7 +164,11 @@ object SetCommand {
 case object ResetCommand extends RunnableCommand with Logging {
 
   override def run(sparkSession: SparkSession): Seq[Row] = {
-    sparkSession.sessionState.conf.clear()
+    val conf = sparkSession.sessionState.conf
+    conf.clear()
+    sparkSession.sparkContext.conf.getAll.foreach { case (k, v) =>
+      conf.setConfString(k, v)
+    }
     Seq.empty[Row]
   }
 }

sql/core/src/test/scala/org/apache/spark/sql/SparkSessionBuilderSuite.scala

@@ -21,6 +21,7 @@ import org.scalatest.BeforeAndAfterEach
 
 import org.apache.spark.{SparkConf, SparkContext, SparkFunSuite}
 import org.apache.spark.sql.internal.SQLConf
+import org.apache.spark.sql.internal.StaticSQLConf.GLOBAL_TEMP_DATABASE
 
 /**
  * Test cases for the builder pattern of [[SparkSession]].
@@ -151,4 +152,19 @@ class SparkSessionBuilderSuite extends SparkFunSuite with BeforeAndAfterEach {
       session.sparkContext.hadoopConfiguration.unset(mySpecialKey)
     }
   }
+
+  test("SPARK-31234: RESET command will not change static sql configs and " +
+    "spark context conf values in SessionState") {
+    val session = SparkSession.builder()
+      .master("local")
+      .config(GLOBAL_TEMP_DATABASE.key, value = "globalTempDB-SPARK-31234")
+      .config("spark.app.name", "test-app-SPARK-31234")
+      .getOrCreate()
+
+    assert(session.sessionState.conf.getConfString("spark.app.name") === "test-app-SPARK-31234")
+    assert(session.sessionState.conf.getConf(GLOBAL_TEMP_DATABASE) === "globalTempDB-SPARK-31234")
+    session.sql("RESET")
+    assert(session.sessionState.conf.getConfString("spark.app.name") === "test-app-SPARK-31234")
+    assert(session.sessionState.conf.getConf(GLOBAL_TEMP_DATABASE) === "globalTempDB-SPARK-31234")
+  }
 }

sql/core/src/test/scala/org/apache/spark/sql/internal/SQLConfSuite.scala

@@ -114,6 +114,21 @@ class SQLConfSuite extends QueryTest with SharedSQLContext {
     }
   }
 
+  test("SPARK-31234: reset will not change static sql configs and spark core configs") {
+    val conf = spark.sparkContext.getConf.getAll.toMap
+    val appName = conf.get("spark.app.name")
+    val driverHost = conf.get("spark.driver.host")
+    val master = conf.get("spark.master")
+    val warehouseDir = conf.get("spark.sql.warehouse.dir")
+    // ensure the conf here is not default value, and will not be reset to default value later
+    assert(warehouseDir.get.contains(this.getClass.getCanonicalName))
+    sql("RESET")
+    assert(conf.get("spark.app.name") === appName)
+    assert(conf.get("spark.driver.host") === driverHost)
+    assert(conf.get("spark.master") === master)
+    assert(conf.get("spark.sql.warehouse.dir") === warehouseDir)
+  }
+
   test("reset - public conf") {
     spark.sessionState.conf.clear()
     val original = spark.conf.get(SQLConf.GROUP_BY_ORDINAL)