From ec5e85f73cb7bfbb9293cacacc8dc68d4287f02a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=BA=84=E5=A4=A9=E7=BF=BC?= <zty0826@gmail.com>
Date: Tue, 12 Nov 2019 12:29:26 +0800
Subject: [PATCH] =?UTF-8?q?expression:=20implement=20vectorized=20evaluati?=
 =?UTF-8?q?on=20for=20`builtinTrunca=E2=80=A6=20(#13317)?=
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---
 expression/builtin_math_vec.go      | 30 +++++++++++++++++++++++++++--
 expression/builtin_math_vec_test.go |  1 +
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/expression/builtin_math_vec.go b/expression/builtin_math_vec.go
index 118c17fd9d..3764a16cdd 100644
--- a/expression/builtin_math_vec.go
+++ b/expression/builtin_math_vec.go
@@ -865,11 +865,37 @@ func (b *builtinFloorDecToDecSig) vecEvalDecimal(input *chunk.Chunk, result *chu
 }
 
 func (b *builtinTruncateDecimalSig) vectorized() bool {
-	return false
+	return true
 }
 
 func (b *builtinTruncateDecimalSig) vecEvalDecimal(input *chunk.Chunk, result *chunk.Column) error {
-	return errors.Errorf("not implemented")
+	n := input.NumRows()
+	if err := b.args[0].VecEvalDecimal(b.ctx, input, result); err != nil {
+		return err
+	}
+	buf, err := b.bufAllocator.get(types.ETInt, n)
+	if err != nil {
+		return err
+	}
+	defer b.bufAllocator.put(buf)
+	if err := b.args[1].VecEvalInt(b.ctx, input, buf); err != nil {
+		return err
+	}
+	result.MergeNulls(buf)
+	ds := result.Decimals()
+	i64s := buf.Int64s()
+	ft := b.getRetTp().Decimal
+	for i := 0; i < n; i++ {
+		if result.IsNull(i) {
+			continue
+		}
+		result := new(types.MyDecimal)
+		if err := ds[i].Round(result, mathutil.Min(int(i64s[i]), ft), types.ModeTruncate); err != nil {
+			return err
+		}
+		ds[i] = *result
+	}
+	return nil
 }
 
 func (b *builtinRoundWithFracDecSig) vectorized() bool {
diff --git a/expression/builtin_math_vec_test.go b/expression/builtin_math_vec_test.go
index 8449972e87..19bb2bfc1e 100644
--- a/expression/builtin_math_vec_test.go
+++ b/expression/builtin_math_vec_test.go
@@ -109,6 +109,7 @@ var vecBuiltinMathCases = map[string][]vecExprBenchCase{
 		{retEvalType: types.ETReal, childrenTypes: []types.EvalType{types.ETReal, types.ETInt}, geners: []dataGenerator{nil, &rangeInt64Gener{-10, 10}}},
 		{retEvalType: types.ETInt, childrenTypes: []types.EvalType{types.ETInt, types.ETInt}, geners: []dataGenerator{nil, &rangeInt64Gener{-10, 10}}},
 		{retEvalType: types.ETInt, childrenTypes: []types.EvalType{types.ETInt, types.ETInt}, childrenFieldTypes: []*types.FieldType{{Tp: mysql.TypeInt24, Flag: mysql.UnsignedFlag}}, geners: []dataGenerator{nil, &rangeInt64Gener{-10, 10}}},
+		{retEvalType: types.ETDecimal, childrenTypes: []types.EvalType{types.ETDecimal, types.ETInt}},
 	},
 	ast.Rand: {
 		{retEvalType: types.ETReal, childrenTypes: []types.EvalType{types.ETInt}, geners: []dataGenerator{&defaultGener{0, types.ETInt}}},