[MINOR][SQL][DOCS] Update `sql/README.md` and remove some unused imports in `sql` module.

## What changes were proposed in this pull request?

This PR updates `sql/README.md` according to the latest console output and removes some unused imports in `sql` module. This is done by manually, so there is no guarantee to remove all unused imports.

## How was this patch tested?

Manual.

Author: Dongjoon Hyun <dongjoon@apache.org>

Closes #11907 from dongjoon-hyun/update_sql_module.

13 files changed, 9 insertions, 23 deletions

diff --git a/sql/README.md b/sql/README.md
index 9ea271d33d..b0903980a5 100644
--- a/sql/README.md
+++ b/sql/README.md
@@ -47,7 +47,7 @@ An interactive scala console can be invoked by running `build/sbt hive/console`.
 From here you can execute queries with HiveQl and manipulate DataFrame by using DSL.
 
 ```scala
-catalyst$ build/sbt hive/console
+$ build/sbt hive/console
 
 [info] Starting scala interpreter...
 import org.apache.spark.sql.catalyst.analysis._
@@ -61,22 +61,23 @@ import org.apache.spark.sql.execution
 import org.apache.spark.sql.functions._
 import org.apache.spark.sql.hive._
 import org.apache.spark.sql.hive.test.TestHive._
+import org.apache.spark.sql.hive.test.TestHive.implicits._
 import org.apache.spark.sql.types._
 Type in expressions to have them evaluated.
 Type :help for more information.
 
 scala> val query = sql("SELECT * FROM (SELECT * FROM src) a")
-query: org.apache.spark.sql.DataFrame = org.apache.spark.sql.DataFrame@74448eed
+query: org.apache.spark.sql.DataFrame = [key: int, value: string]
 ```
 
 Query results are `DataFrames` and can be operated as such.
 ```
 scala> query.collect()
-res2: Array[org.apache.spark.sql.Row] = Array([238,val_238], [86,val_86], [311,val_311], [27,val_27]...
+res0: Array[org.apache.spark.sql.Row] = Array([238,val_238], [86,val_86], [311,val_311], [27,val_27]...
 ```
 
 You can also build further queries on top of these `DataFrames` using the query DSL.
 ```
 scala> query.where(query("key") > 30).select(avg(query("key"))).collect()
-res3: Array[org.apache.spark.sql.Row] = Array([274.79025423728814])
+res1: Array[org.apache.spark.sql.Row] = Array([274.79025423728814])
 ```
diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/LogicalPlan.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/LogicalPlan.scala
index 01c1fa40dc..ecf4285c46 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/LogicalPlan.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/plans/logical/LogicalPlan.scala
@@ -22,7 +22,7 @@ import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.analysis._
 import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.catalyst.plans.QueryPlan
-import org.apache.spark.sql.catalyst.trees.{CurrentOrigin, TreeNode}
+import org.apache.spark.sql.catalyst.trees.CurrentOrigin
 import org.apache.spark.sql.types.StructType
 
 
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala b/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
index c070e867c9..542f2f4deb 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/SQLContext.scala
@@ -32,13 +32,9 @@ import org.apache.spark.internal.Logging
 import org.apache.spark.rdd.RDD
 import org.apache.spark.scheduler.{SparkListener, SparkListenerApplicationEnd}
 import org.apache.spark.sql.catalyst._
-import org.apache.spark.sql.catalyst.analysis._
 import org.apache.spark.sql.catalyst.encoders.encoderFor
 import org.apache.spark.sql.catalyst.expressions._
-import org.apache.spark.sql.catalyst.optimizer.Optimizer
-import org.apache.spark.sql.catalyst.parser.ParserInterface
 import org.apache.spark.sql.catalyst.plans.logical.{LocalRelation, LogicalPlan, Range}
-import org.apache.spark.sql.catalyst.rules.RuleExecutor
 import org.apache.spark.sql.execution._
 import org.apache.spark.sql.execution.command.ShowTablesCommand
 import org.apache.spark.sql.execution.datasources._
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/SQLImplicits.scala b/sql/core/src/main/scala/org/apache/spark/sql/SQLImplicits.scala
index 4aab16b866..c35a969bf0 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/SQLImplicits.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/SQLImplicits.scala
@@ -21,11 +21,7 @@ import scala.language.implicitConversions
 import scala.reflect.runtime.universe.TypeTag
 
 import org.apache.spark.rdd.RDD
-import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.encoders.ExpressionEncoder
-import org.apache.spark.sql.catalyst.expressions.SpecificMutableRow
-import org.apache.spark.sql.types._
-import org.apache.spark.unsafe.types.UTF8String
 
 /**
  * A collection of implicit methods for converting common Scala objects into [[DataFrame]]s.
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkQl.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkQl.scala
index 11391bd12a..ef30ba0cdb 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkQl.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/SparkQl.scala
@@ -18,7 +18,6 @@ package org.apache.spark.sql.execution
 
 import org.apache.spark.sql.{AnalysisException, SaveMode}
 import org.apache.spark.sql.catalyst.TableIdentifier
-import org.apache.spark.sql.catalyst.analysis.UnresolvedRelation
 import org.apache.spark.sql.catalyst.parser._
 import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, OneRowRelation}
 import org.apache.spark.sql.execution.command._
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegen.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegen.scala
index e3c7d7209a..5634e5fc58 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegen.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/WholeStageCodegen.scala
@@ -22,7 +22,6 @@ import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.expressions._
 import org.apache.spark.sql.catalyst.expressions.codegen._
-import org.apache.spark.sql.catalyst.plans.Inner
 import org.apache.spark.sql.catalyst.plans.physical.Partitioning
 import org.apache.spark.sql.catalyst.rules.Rule
 import org.apache.spark.sql.catalyst.util.toCommentSafeString
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala b/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala
index 855295d5f2..a1b45ca7eb 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/QueryTest.scala
@@ -31,7 +31,6 @@ import org.apache.spark.sql.catalyst.util._
 import org.apache.spark.sql.execution.{LogicalRDD, Queryable}
 import org.apache.spark.sql.execution.columnar.InMemoryRelation
 import org.apache.spark.sql.execution.datasources.LogicalRelation
-import org.apache.spark.sql.internal.SQLConf
 
 abstract class QueryTest extends PlanTest {
 
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/StreamTest.scala b/sql/core/src/test/scala/org/apache/spark/sql/StreamTest.scala
index 26c597bf34..62dc492d60 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/StreamTest.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/StreamTest.scala
@@ -28,7 +28,6 @@ import scala.util.control.NonFatal
 
 import org.scalatest.Assertions
 import org.scalatest.concurrent.{Eventually, Timeouts}
-import org.scalatest.concurrent.Eventually.timeout
 import org.scalatest.concurrent.PatienceConfiguration.Timeout
 import org.scalatest.exceptions.TestFailedDueToTimeoutException
 import org.scalatest.time.Span
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/PlannerSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/PlannerSuite.scala
index e9b65539b0..bdbcf842ca 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/PlannerSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/PlannerSuite.scala
@@ -26,7 +26,7 @@ import org.apache.spark.sql.catalyst.plans.logical.{LogicalPlan, Repartition}
 import org.apache.spark.sql.catalyst.plans.physical._
 import org.apache.spark.sql.execution.columnar.InMemoryRelation
 import org.apache.spark.sql.execution.exchange.{EnsureRequirements, ReusedExchange, ReuseExchange, ShuffleExchange}
-import org.apache.spark.sql.execution.joins.{BroadcastHashJoin, ShuffledHashJoin, SortMergeJoin}
+import org.apache.spark.sql.execution.joins.{BroadcastHashJoin, SortMergeJoin}
 import org.apache.spark.sql.functions._
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.test.SharedSQLContext
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/WholeStageCodegenSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/WholeStageCodegenSuite.scala
index 716c367eae..6d5be0b5dd 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/WholeStageCodegenSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/WholeStageCodegenSuite.scala
@@ -18,7 +18,6 @@
 package org.apache.spark.sql.execution
 
 import org.apache.spark.sql.Row
-import org.apache.spark.sql.catalyst.dsl.expressions._
 import org.apache.spark.sql.execution.aggregate.TungstenAggregate
 import org.apache.spark.sql.execution.joins.BroadcastHashJoin
 import org.apache.spark.sql.functions.{avg, broadcast, col, max}
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/FileSourceStrategySuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/FileSourceStrategySuite.scala
index 2f8129c5da..4abc6d6a55 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/FileSourceStrategySuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/FileSourceStrategySuite.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.execution.datasources
 
-import java.io.{File, FilenameFilter}
+import java.io.File
 
 import org.apache.hadoop.fs.FileStatus
 import org.apache.hadoop.mapreduce.Job
@@ -28,7 +28,7 @@ import org.apache.spark.sql._
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.expressions.{Expression, ExpressionSet, PredicateHelper}
 import org.apache.spark.sql.catalyst.util
-import org.apache.spark.sql.execution.{DataSourceScan, PhysicalRDD}
+import org.apache.spark.sql.execution.DataSourceScan
 import org.apache.spark.sql.functions._
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.sources._
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetReadBenchmark.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetReadBenchmark.scala
index cc0cc65d3e..cef541f044 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetReadBenchmark.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/parquet/ParquetReadBenchmark.scala
@@ -22,7 +22,6 @@ import scala.collection.JavaConverters._
 import scala.util.Try
 
 import org.apache.spark.{SparkConf, SparkContext}
-import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.internal.SQLConf
 import org.apache.spark.sql.SQLContext
 import org.apache.spark.util.{Benchmark, Utils}
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/joins/HashedRelationSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/joins/HashedRelationSuite.scala
index dd20855a81..e19b4ff1e2 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/joins/HashedRelationSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/joins/HashedRelationSuite.scala
@@ -22,7 +22,6 @@ import java.io.{ByteArrayInputStream, ByteArrayOutputStream, ObjectInputStream,
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.sql.catalyst.InternalRow
 import org.apache.spark.sql.catalyst.expressions._
-import org.apache.spark.sql.execution.metric.SQLMetrics
 import org.apache.spark.sql.test.SharedSQLContext
 import org.apache.spark.sql.types.{IntegerType, StructField, StructType}
 import org.apache.spark.util.collection.CompactBuffer