address reviewer's comment

executor/builder.go

@@ -618,6 +618,19 @@ func (b *executorBuilder) buildDDL(v *plan.DDL) Executor {
 	return e
 }
 
+// buildExplain builds a explain executor. `e.rows` collects final result and
+// displays it in sql-shell.
+func (b *executorBuilder) buildExplain(v *plan.Explain) Executor {
+	e := &ExplainExec{
+		baseExecutor: newBaseExecutor(b.ctx, v.Schema(), v.ExplainID()),
+	}
+	e.rows = make([][]string, 0, len(v.Rows))
+	for _, row := range v.Rows {
+		e.rows = append(e.rows, row)
+	}
+	return e
+}
+
 func (b *executorBuilder) buildUnionScanExec(v *plan.PhysicalUnionScan) Executor {
 	src := b.build(v.Children()[0])
 	if b.err != nil {

executor/explain.go

@@ -15,7 +15,6 @@ package executor
 
 import (
 	"github.com/cznic/mathutil"
-	"github.com/pingcap/tidb/plan"
 	"github.com/pingcap/tidb/util/chunk"
 	"golang.org/x/net/context"
 )
@@ -28,19 +27,6 @@ type ExplainExec struct {
 	cursor int
 }
 
-// buildExplain builds a explain executor. `e.rows` collects final result and
-// displays it in sql-shell.
-func (b *executorBuilder) buildExplain(v *plan.Explain) Executor {
-	e := &ExplainExec{
-		baseExecutor: newBaseExecutor(b.ctx, v.Schema(), v.ExplainID()),
-	}
-	e.rows = make([][]string, 0, len(v.Rows))
-	for _, row := range v.Rows {
-		e.rows = append(e.rows, row)
-	}
-	return e
-}
-
 // Close implements the Executor Close interface.
 func (e *ExplainExec) Close() error {
 	e.rows = nil

executor/table_reader.go

@@ -26,7 +26,7 @@ import (
 	"golang.org/x/net/context"
 )
 
-// TableReaderExecutor sends dag request and reads table data from kv layer.
+// TableReaderExecutor sends DAG request and reads table data from kv layer.
 type TableReaderExecutor struct {
 	baseExecutor
 
@@ -52,23 +52,6 @@ type TableReaderExecutor struct {
 	plans          []plan.PhysicalPlan
 }
 
-// Close implements the Executor Close interface.
-func (e *TableReaderExecutor) Close() error {
-	e.ctx.StoreQueryFeedback(e.feedback)
-	err := e.resultHandler.Close()
-	return errors.Trace(err)
-}
-
-// Next fills data into the chunk passed by its caller.
-// The task was actually done by tableReaderHandler.
-func (e *TableReaderExecutor) Next(ctx context.Context, chk *chunk.Chunk) error {
-	err := e.resultHandler.nextChunk(ctx, chk)
-	if err != nil {
-		e.feedback.Invalidate()
-	}
-	return errors.Trace(err)
-}
-
 // Open initialzes necessary variables for using this executor.
 func (e *TableReaderExecutor) Open(ctx context.Context) error {
 	span, ctx := startSpanFollowsContext(ctx, "executor.TableReader.Open")
@@ -112,6 +95,23 @@ func (e *TableReaderExecutor) Open(ctx context.Context) error {
 	return nil
 }
 
+// Next fills data into the chunk passed by its caller.
+// The task was actually done by tableReaderHandler.
+func (e *TableReaderExecutor) Next(ctx context.Context, chk *chunk.Chunk) error {
+	err := e.resultHandler.nextChunk(ctx, chk)
+	if err != nil {
+		e.feedback.Invalidate()
+	}
+	return errors.Trace(err)
+}
+
+// Close implements the Executor Close interface.
+func (e *TableReaderExecutor) Close() error {
+	e.ctx.StoreQueryFeedback(e.feedback)
+	err := e.resultHandler.Close()
+	return errors.Trace(err)
+}
+
 // buildResp first build request and send it to tikv using distsql.Select. It uses SelectResut returned by the callee
 // to fetch all results.
 func (e *TableReaderExecutor) buildResp(ctx context.Context, ranges []*ranger.Range) (distsql.SelectResult, error) {