doc update

Author: xuanyuanking

sql/catalyst/src/main/scala/org/apache/spark/sql/internal/SQLConf.scala

@@ -355,29 +355,33 @@ object SQLConf {
 
   val SHUFFLE_TARGET_POSTSHUFFLE_INPUT_SIZE =
     buildConf("spark.sql.adaptive.shuffle.targetPostShuffleInputSize")
-      .doc("The target post-shuffle input size in bytes of a task.")
+      .doc("The target post-shuffle input size in bytes of a task. This configuration only has " +
+        s"an effect when '${ADAPTIVE_EXECUTION_ENABLED.key}' is enabled.")
       .bytesConf(ByteUnit.BYTE)
       .createWithDefault(64 * 1024 * 1024)
 
   val FETCH_SHUFFLE_BLOCKS_IN_BATCH_ENABLED =
     buildConf("spark.sql.adaptive.shuffle.fetchShuffleBlocksInBatch.enabled")
       .doc("Whether to fetch the continuous shuffle blocks in batch. Instead of fetching blocks " +
         "one by one, fetching continuous shuffle blocks for the same map task in batch can " +
-        "reduce IO and improve performance. Note, this feature also depends on a relocatable " +
-        "serializer and the concatenation support codec in use.")
+        "reduce IO and improve performance. Note, multiple continuous blocks exist in single " +
+        s"fetch request only happen when '${ADAPTIVE_EXECUTION_ENABLED.key}' is enabled, " +
+        "this feature also depends on a relocatable serializer and the concatenation support " +
+        "codec in use.")
       .booleanConf
       .createWithDefault(true)
 
   val REDUCE_POST_SHUFFLE_PARTITIONS_ENABLED =
     buildConf("spark.sql.adaptive.shuffle.reducePostShufflePartitions.enabled")
-    .doc("When true and adaptive execution is enabled, this enables reducing the number of " +
-      "post-shuffle partitions based on map output statistics.")
+    .doc(s"When true and '${ADAPTIVE_EXECUTION_ENABLED.key}' is enabled, this enables reducing " +
+      "the number of post-shuffle partitions based on map output statistics.")
     .booleanConf
     .createWithDefault(true)
 
   val SHUFFLE_MIN_NUM_POSTSHUFFLE_PARTITIONS =
     buildConf("spark.sql.adaptive.shuffle.minNumPostShufflePartitions")
-      .doc("The advisory minimum number of post-shuffle partitions used in adaptive execution.")
+      .doc("The advisory minimum number of post-shuffle partitions used when " +
+        s"'${ADAPTIVE_EXECUTION_ENABLED.key}' is enabled.")
       .intConf
       .checkValue(_ > 0, "The minimum shuffle partition number " +
         "must be a positive integer.")
@@ -387,25 +391,27 @@ object SQLConf {
     buildConf("spark.sql.adaptive.shuffle.maxNumPostShufflePartitions")
       .doc("The advisory maximum number of post-shuffle partitions used in adaptive execution. " +
         "This is used as the initial number of pre-shuffle partitions. By default it equals to " +
-        "spark.sql.shuffle.partitions")
+        "spark.sql.shuffle.partitions. This configuration only has an effect when " +
+        s"'${ADAPTIVE_EXECUTION_ENABLED.key}' is enabled.")
       .intConf
       .checkValue(_ > 0, "The maximum shuffle partition number " +
         "must be a positive integer.")
       .createOptional
 
   val LOCAL_SHUFFLE_READER_ENABLED =
     buildConf("spark.sql.adaptive.shuffle.localShuffleReader.enabled")
-    .doc("When true and adaptive execution is enabled, this enables the optimization of" +
-      " converting the shuffle reader to local shuffle reader for the shuffle exchange" +
-      " of the broadcast hash join in probe side.")
+    .doc(s"When true and '${ADAPTIVE_EXECUTION_ENABLED.key}' is enabled, this enables the " +
+      "optimization of converting the shuffle reader to local shuffle reader for the shuffle " +
+      "exchange of the broadcast hash join in probe side.")
     .booleanConf
     .createWithDefault(true)
 
   val NON_EMPTY_PARTITION_RATIO_FOR_BROADCAST_JOIN =
     buildConf("spark.sql.adaptive.nonEmptyPartitionRatioForBroadcastJoin")
       .doc("The relation with a non-empty partition ratio lower than this config will not be " +
         "considered as the build side of a broadcast-hash join in adaptive execution regardless " +
-        "of its size.")
+        "of its size.This configuration only has an effect when " +
+        s"'${ADAPTIVE_EXECUTION_ENABLED.key}' is enabled.")
       .doubleConf
       .checkValue(_ >= 0, "The non-empty partition ratio must be positive number.")
       .createWithDefault(0.2)