For review

common/src/main/scala/org/apache/comet/CometConf.scala

@@ -133,13 +133,12 @@ object CometConf {
       .createWithDefault(false)
 
   val COMET_SHUFFLE_MODE: ConfigEntry[String] = conf(s"$COMET_EXEC_CONFIG_PREFIX.shuffle.mode")
-    .doc(
-      "The mode of Comet shuffle. This config is only effective only if Comet shuffle " +
-        "is enabled. Available modes are 'native', 'jvm', and 'auto'. " +
-        "'native' is for native shuffle which has best performance in general." +
-        "'jvm' is for jvm-based columnar shuffle which has higher coverage than native shuffle." +
-        "'auto' is for Comet to choose the best shuffle mode based on the query plan." +
-        "By default, this config is 'jvm'.")
+    .doc("The mode of Comet shuffle. This config is only effective if Comet shuffle " +
+      "is enabled. Available modes are 'native', 'jvm', and 'auto'. " +
+      "'native' is for native shuffle which has best performance in general. " +
+      "'jvm' is for jvm-based columnar shuffle which has higher coverage than native shuffle. " +
+      "'auto' is for Comet to choose the best shuffle mode based on the query plan. " +
+      "By default, this config is 'jvm'.")
     .stringConf
     .transform(_.toLowerCase(Locale.ROOT))
     .checkValues(Set("native", "jvm", "auto"))

docs/source/user-guide/configs.md

@@ -38,7 +38,7 @@ Comet provides the following configuration settings.
 | spark.comet.exec.memoryFraction | The fraction of memory from Comet memory overhead that the native memory manager can use for execution. The purpose of this config is to set aside memory for untracked data structures, as well as imprecise size estimation during memory acquisition. Default value is 0.7. | 0.7 |
 | spark.comet.exec.shuffle.codec | The codec of Comet native shuffle used to compress shuffle data. Only zstd is supported. | zstd |
 | spark.comet.exec.shuffle.enabled | Whether to enable Comet native shuffle. By default, this config is false. Note that this requires setting 'spark.shuffle.manager' to 'org.apache.spark.sql.comet.execution.shuffle.CometShuffleManager'. 'spark.shuffle.manager' must be set before starting the Spark application and cannot be changed during the application. | false |
-| spark.comet.exec.shuffle.mode | The mode of Comet shuffle. This config is only effective only if Comet shuffle is enabled. Available modes are 'native', 'jvm', and 'auto'. 'native' is for native shuffle which has best performance in general.'jvm' is for jvm-based columnar shuffle which has higher coverage than native shuffle.'auto' is for Comet to choose the best shuffle mode based on the query plan.By default, this config is 'jvm'. | jvm |
+| spark.comet.exec.shuffle.mode | The mode of Comet shuffle. This config is only effective if Comet shuffle is enabled. Available modes are 'native', 'jvm', and 'auto'. 'native' is for native shuffle which has best performance in general. 'jvm' is for jvm-based columnar shuffle which has higher coverage than native shuffle. 'auto' is for Comet to choose the best shuffle mode based on the query plan. By default, this config is 'jvm'. | jvm |
 | spark.comet.explainFallback.enabled | When this setting is enabled, Comet will provide logging explaining the reason(s) why a query stage cannot be executed natively. | false |
 | spark.comet.memory.overhead.factor | Fraction of executor memory to be allocated as additional non-heap memory per executor process for Comet. Default value is 0.2. | 0.2 |
 | spark.comet.memory.overhead.min | Minimum amount of additional memory to be allocated per executor process for Comet, in MiB. | 402653184b |

spark/src/test/scala/org/apache/comet/exec/CometAggregateSuite.scala

@@ -1016,8 +1016,8 @@ class CometAggregateSuite extends CometTestBase with AdaptiveSparkPlanHelper {
 
   test("test bool_and/bool_or") {
     withSQLConf(CometConf.COMET_EXEC_SHUFFLE_ENABLED.key -> "true") {
-      Seq("native", "jvm").foreach { cometColumnShuffleEnabled =>
-        withSQLConf(CometConf.COMET_SHUFFLE_MODE.key -> cometColumnShuffleEnabled.toString) {
+      Seq("native", "jvm").foreach { cometShuffleMode =>
+        withSQLConf(CometConf.COMET_SHUFFLE_MODE.key -> cometShuffleMode) {
           Seq(true, false).foreach { dictionary =>
             withSQLConf("parquet.enable.dictionary" -> dictionary.toString) {
               val table = "test"
@@ -1091,8 +1091,8 @@ class CometAggregateSuite extends CometTestBase with AdaptiveSparkPlanHelper {
 
   test("covar_pop and covar_samp") {
     withSQLConf(CometConf.COMET_EXEC_SHUFFLE_ENABLED.key -> "true") {
-      Seq("native", "jvm").foreach { cometColumnShuffleEnabled =>
-        withSQLConf(CometConf.COMET_SHUFFLE_MODE.key -> cometColumnShuffleEnabled) {
+      Seq("native", "jvm").foreach { cometShuffleMode =>
+        withSQLConf(CometConf.COMET_SHUFFLE_MODE.key -> cometShuffleMode) {
           Seq(true, false).foreach { dictionary =>
             withSQLConf("parquet.enable.dictionary" -> dictionary.toString) {
               val table = "test"
@@ -1129,8 +1129,8 @@ class CometAggregateSuite extends CometTestBase with AdaptiveSparkPlanHelper {
 
   test("var_pop and var_samp") {
     withSQLConf(CometConf.COMET_EXEC_SHUFFLE_ENABLED.key -> "true") {
-      Seq("native", "jvm").foreach { cometColumnShuffleEnabled =>
-        withSQLConf(CometConf.COMET_SHUFFLE_MODE.key -> cometColumnShuffleEnabled) {
+      Seq("native", "jvm").foreach { cometShuffleMode =>
+        withSQLConf(CometConf.COMET_SHUFFLE_MODE.key -> cometShuffleMode) {
           Seq(true, false).foreach { dictionary =>
             withSQLConf("parquet.enable.dictionary" -> dictionary.toString) {
               Seq(true, false).foreach { nullOnDivideByZero =>
@@ -1168,8 +1168,8 @@ class CometAggregateSuite extends CometTestBase with AdaptiveSparkPlanHelper {
 
   test("stddev_pop and stddev_samp") {
     withSQLConf(CometConf.COMET_EXEC_SHUFFLE_ENABLED.key -> "true") {
-      Seq("native", "jvm").foreach { cometColumnShuffleEnabled =>
-        withSQLConf(CometConf.COMET_SHUFFLE_MODE.key -> cometColumnShuffleEnabled) {
+      Seq("native", "jvm").foreach { cometShuffleMode =>
+        withSQLConf(CometConf.COMET_SHUFFLE_MODE.key -> cometShuffleMode) {
           Seq(true, false).foreach { dictionary =>
             withSQLConf("parquet.enable.dictionary" -> dictionary.toString) {
               Seq(true, false).foreach { nullOnDivideByZero =>

spark/src/test/scala/org/apache/comet/exec/CometExecSuite.scala

@@ -134,14 +134,15 @@ class CometExecSuite extends CometTestBase {
         .toDF("c1", "c2")
         .createOrReplaceTempView("v")
 
-      Seq("native", "jvm").foreach { columnarShuffle =>
+      Seq("native", "jvm").foreach { columnarShuffleMode =>
         withSQLConf(
           SQLConf.ADAPTIVE_EXECUTION_ENABLED.key -> "false",
-          CometConf.COMET_SHUFFLE_MODE.key -> columnarShuffle.toString) {
+          CometConf.COMET_SHUFFLE_MODE.key -> columnarShuffleMode) {
           val df = sql("SELECT * FROM v where c1 = 1 order by c1, c2")
           val shuffle = find(df.queryExecution.executedPlan) {
-            case _: CometShuffleExchangeExec if columnarShuffle.equalsIgnoreCase("jvm") => true
-            case _: ShuffleExchangeExec if !columnarShuffle.equalsIgnoreCase("jvm") => true
+            case _: CometShuffleExchangeExec if columnarShuffleMode.equalsIgnoreCase("jvm") =>
+              true
+            case _: ShuffleExchangeExec if !columnarShuffleMode.equalsIgnoreCase("jvm") => true
             case _ => false
           }.get
           assert(shuffle.logicalLink.isEmpty)
@@ -764,10 +765,10 @@ class CometExecSuite extends CometTestBase {
   }
 
   test("limit") {
-    Seq("native", "jvm").foreach { columnarShuffle =>
+    Seq("native", "jvm").foreach { columnarShuffleMode =>
       withSQLConf(
         CometConf.COMET_EXEC_SHUFFLE_ENABLED.key -> "true",
-        CometConf.COMET_SHUFFLE_MODE.key -> columnarShuffle) {
+        CometConf.COMET_SHUFFLE_MODE.key -> columnarShuffleMode) {
         withParquetTable((0 until 5).map(i => (i, i + 1)), "tbl_a") {
           val df = sql("SELECT * FROM tbl_a")
             .repartition(10, $"_1")