expression: implement vectorized evaluation for builtinLowerStr

expression/bench_test.go

@@ -204,6 +204,9 @@ var vecExprBenchCases = map[string][]vecExprBenchCase{
 	ast.Cast: {
 		{types.ETInt, []types.EvalType{types.ETInt}},
 	},
+	ast.Lower: {
+		{types.ETString, []types.EvalType{types.ETString}},
+	},
 }
 
 func fillColumn(eType types.EvalType, chk *chunk.Chunk, colIdx int) {
@@ -283,14 +286,30 @@ func fillColumn(eType types.EvalType, chk *chunk.Chunk, colIdx int) {
 			if rand.Float64() < nullRatio {
 				chk.AppendNull(colIdx)
 			} else {
-				chk.AppendString(colIdx, fmt.Sprintf("%v", rand.Int()))
+				chk.AppendString(colIdx, randString())
 			}
 		}
 	default:
 		panic(fmt.Sprintf("EvalType=%v is not supported.", eType))
 	}
 }
 
+func randString() string {
+	n := 10 + rand.Intn(10)
+	buf := make([]byte, n)
+	for i := range buf {
+		x := rand.Intn(62)
+		if x < 10 {
+			buf[i] = byte('0' + x)
+		} else if x-10 < 26 {
+			buf[i] = byte('a' + x - 10)
+		} else {
+			buf[i] = byte('A' + x - 10 - 26)
+		}
+	}
+	return string(buf)
+}
+
 func eType2FieldType(eType types.EvalType) *types.FieldType {
 	switch eType {
 	case types.ETInt:
@@ -532,7 +551,7 @@ func (s *testEvaluatorSuite) TestVectorizedBuiltinFunc(c *C) {
 				err := baseFunc.vecEvalJSON(input, output)
 				c.Assert(err, IsNil)
 				for row := it.Begin(); row != it.End(); row = it.Next() {
-					val, isNull, err := baseFunc.evalDuration(row)
+					val, isNull, err := baseFunc.evalJSON(row)
 					c.Assert(err, IsNil)
 					c.Assert(isNull, Equals, output.IsNull(i))
 					if !isNull {
@@ -544,7 +563,7 @@ func (s *testEvaluatorSuite) TestVectorizedBuiltinFunc(c *C) {
 				err := baseFunc.vecEvalString(input, output)
 				c.Assert(err, IsNil)
 				for row := it.Begin(); row != it.End(); row = it.Next() {
-					val, isNull, err := baseFunc.evalDuration(row)
+					val, isNull, err := baseFunc.evalString(row)
 					c.Assert(err, IsNil)
 					c.Assert(isNull, Equals, output.IsNull(i))
 					if !isNull {

expression/builtin_string_vec.go

@@ -0,0 +1,51 @@
+// Copyright 2019 PingCAP, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package expression
+
+import (
+	"github.com/pingcap/tidb/types"
+	"github.com/pingcap/tidb/util/chunk"
+	"unicode/utf8"
+)
+
+func (b *builtinLowerSig) vecEvalString(input *chunk.Chunk, result *chunk.Column) error {
+	if err := b.args[0].VecEvalString(b.ctx, input, result); err != nil {
+		return err
+	}
+	if types.IsBinaryStr(b.args[0].GetType()) {
+		return nil
+	}
+	for i := 0; i < input.NumRows(); i++ {
+		str := result.GetBytes(i)
+		isASCII := true
+		for _, c := range str {
+			if c >= utf8.RuneSelf {
+				isASCII = false
+			}
+		}
+		if !isASCII {
+			continue
+		}
+		for i := range str {
+			if str[i] >= 'A' && str[i] <= 'Z' {
+				str[i] += 'a' - 'A'
+			}
+		}
+	}
+	return nil
+}
+
+func (b *builtinLowerSig) vectorized() bool {
+	return true
+}