From 04e3d653d6c5b7a23f7084e005915e2448c641f2 Mon Sep 17 00:00:00 2001
From: Ewan Chou <coocood@gmail.com>
Date: Tue, 3 Apr 2018 17:06:33 +0800
Subject: [PATCH] column: fix zero value for binary type

Zero value for BINARY type should be byte slice with length.
---
 table/column.go      |  9 ++++++++-
 table/column_test.go | 10 ++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/table/column.go b/table/column.go
index 5e5e7b92a6f71..5bc63ff27c777 100644
--- a/table/column.go
+++ b/table/column.go
@@ -29,6 +29,7 @@ import (
 	"github.com/pingcap/tidb/sessionctx"
 	"github.com/pingcap/tidb/types"
 	"github.com/pingcap/tidb/types/json"
+	"github.com/pingcap/tidb/util/charset"
 	"github.com/pingcap/tidb/util/hack"
 	log "github.com/sirupsen/logrus"
 )
@@ -370,7 +371,13 @@ func GetZeroValue(col *model.ColumnInfo) types.Datum {
 		d.SetFloat64(0)
 	case mysql.TypeNewDecimal:
 		d.SetMysqlDecimal(new(types.MyDecimal))
-	case mysql.TypeString, mysql.TypeVarString, mysql.TypeVarchar:
+	case mysql.TypeString:
+		if col.Flen > 0 && col.Charset == charset.CharsetBin {
+			d.SetBytes(make([]byte, col.Flen))
+		} else {
+			d.SetString("")
+		}
+	case mysql.TypeVarString, mysql.TypeVarchar:
 		d.SetString("")
 	case mysql.TypeBlob, mysql.TypeTinyBlob, mysql.TypeMediumBlob, mysql.TypeLongBlob:
 		d.SetBytes([]byte{})
diff --git a/table/column_test.go b/table/column_test.go
index 29e6d7d9b8706..45d2d5bdaf529 100644
--- a/table/column_test.go
+++ b/table/column_test.go
@@ -21,6 +21,7 @@ import (
 	"github.com/pingcap/tidb/mysql"
 	"github.com/pingcap/tidb/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/types"
+	"github.com/pingcap/tidb/util/charset"
 	"github.com/pingcap/tidb/util/mock"
 	"github.com/pingcap/tidb/util/testleak"
 )
@@ -193,6 +194,15 @@ func (t *testTableSuite) TestGetZeroValue(c *C) {
 			types.NewFieldType(mysql.TypeEnum),
 			types.NewDatum(types.Enum{}),
 		},
+		{
+			&types.FieldType{
+				Tp:      mysql.TypeString,
+				Flen:    2,
+				Charset: charset.CharsetBin,
+				Collate: charset.CollationBin,
+			},
+			types.NewDatum(make([]byte, 2)),
+		},
 	}
 	sc := new(stmtctx.StatementContext)
 	for _, tt := range tests {