Support client specified collation

server/conn.go

@@ -147,8 +147,11 @@ func (cc *clientConn) writeInitialHandshake() error {
 	data = append(data, 0)
 	// capability flag lower 2 bytes, using default capability here
 	data = append(data, byte(defaultCapability), byte(defaultCapability>>8))
-	// charset, utf-8 default
-	data = append(data, uint8(mysql.DefaultCollationID))
+	// charset
+	if cc.collation == 0 {
+		cc.collation = uint8(mysql.DefaultCollationID)
+	}
+	data = append(data, cc.collation)
 	//status
 	data = append(data, dumpUint16(mysql.ServerStatusAutocommit)...)
 	// below 13 byte may not be used
@@ -204,7 +207,7 @@ func handshakeResponseFromData(packet *handshakeResponse41, data []byte) (err er
 	pos += 4
 	// skip max packet size
 	pos += 4
-	// charset, skip, if you want to use another charset, use set names
+	// charset
 	packet.Collation = data[pos]
 	pos++
 	// skip reserved 23[00]

server/driver_tidb.go

@@ -128,6 +128,10 @@ func (qd *TiDBDriver) OpenCtx(connID uint64, capability uint32, collation uint8,
 	if err != nil {
 		return nil, errors.Trace(err)
 	}
+	err = session.SetCollation(int(collation))
+	if err != nil {
+		return nil, errors.Trace(err)
+	}
 	session.SetClientCapability(capability)
 	session.SetConnectionID(connID)
 	tc := &TiDBContext{

server/server_test.go

@@ -246,6 +246,41 @@ func runTestSpecialType(t *C) {
 	})
 }
 
+func runTestClientWithCollation(t *C) {
+	runTests(t, func(config *mysql.Config) {
+		config.Collation = "utf8mb4_general_ci"
+	}, func(dbt *DBTest) {
+		var name, charset, collation string
+		// check session variable collation_connection
+		rows := dbt.mustQuery("show variables like 'collation_connection'")
+		t.Assert(rows.Next(), IsTrue)
+		err := rows.Scan(&name, &collation)
+		t.Assert(err, IsNil)
+		t.Assert(collation, Equals, "utf8mb4_general_ci")
+
+		// check session variable character_set_client
+		rows = dbt.mustQuery("show variables like 'character_set_client'")
+		t.Assert(rows.Next(), IsTrue)
+		err = rows.Scan(&name, &charset)
+		t.Assert(err, IsNil)
+		t.Assert(charset, Equals, "utf8mb4")
+
+		// check session variable character_set_results
+		rows = dbt.mustQuery("show variables like 'character_set_results'")
+		t.Assert(rows.Next(), IsTrue)
+		err = rows.Scan(&name, &charset)
+		t.Assert(err, IsNil)
+		t.Assert(charset, Equals, "utf8mb4")
+
+		// check session variable character_set_connection
+		rows = dbt.mustQuery("show variables like 'character_set_connection'")
+		t.Assert(rows.Next(), IsTrue)
+		err = rows.Scan(&name, &charset)
+		t.Assert(err, IsNil)
+		t.Assert(charset, Equals, "utf8mb4")
+	})
+}
+
 func runTestPreparedString(t *C) {
 	runTestsOnNewDB(t, nil, "PreparedString", func(dbt *DBTest) {
 		dbt.mustExec("create table test (a char(10), b char(10))")

server/tidb_test.go

@@ -152,3 +152,8 @@ func (ts *TidbTestSuite) TestSocket(c *C) {
 		config.Strict = true
 	}, "SocketRegression")
 }
+
+func (ts *TidbTestSuite) TestClientWithCollation(c *C) {
+	c.Parallel()
+	runTestClientWithCollation(c)
+}

session.go

@@ -49,6 +49,7 @@ import (
 	"github.com/pingcap/tidb/store/tikv/oracle"
 	"github.com/pingcap/tidb/util"
 	"github.com/pingcap/tidb/util/auth"
+	"github.com/pingcap/tidb/util/charset"
 	"github.com/pingcap/tidb/util/types"
 	"github.com/pingcap/tipb/go-binlog"
 	goctx "golang.org/x/net/context"
@@ -71,6 +72,7 @@ type Session interface {
 	DropPreparedStmt(stmtID uint32) error
 	SetClientCapability(uint32) // Set client capability flags.
 	SetConnectionID(uint64)
+	SetCollation(coID int) error
 	SetSessionManager(util.SessionManager)
 	Close()
 	Auth(user *auth.UserIdentity, auth []byte, salt []byte) bool
@@ -181,6 +183,18 @@ func (s *session) SetConnectionID(connectionID uint64) {
 	s.sessionVars.ConnectionID = connectionID
 }
 
+func (s *session) SetCollation(coID int) error {
+	cs, co, err := charset.GetCharsetInfoByID(coID)
+	if err != nil {
+		return errors.Trace(err)
+	}
+	for _, v := range variable.SetNamesVariables {
+		s.sessionVars.Systems[v] = cs
+	}
+	s.sessionVars.Systems[variable.CollationConnection] = co
+	return nil
+}
+
 func (s *session) SetSessionManager(sm util.SessionManager) {
 	s.sessionManager = sm
 }

util/charset/charset.go

@@ -17,6 +17,7 @@ import (
 	"strings"
 
 	"github.com/juju/errors"
+	"github.com/pingcap/tidb/mysql"
 )
 
 // Charset is a charset.
@@ -151,6 +152,19 @@ func GetCharsetDesc(cs string) (*Desc, error) {
 	return desc, nil
 }
 
+// GetCharsetInfoByID returns charset and collation for id as cs_number.
+func GetCharsetInfoByID(coID int) (string, string, error) {
+	if coID == mysql.DefaultCollationID {
+		return mysql.DefaultCharset, mysql.DefaultCollationName, nil
+	}
+	for _, collation := range collations {
+		if coID == collation.ID {
+			return collation.CharsetName, collation.Name, nil
+		}
+	}
+	return "", "", errors.Errorf("Unknown charset id %d", coID)
+}
+
 // GetCollations returns a list for all collations.
 func GetCollations() []*Collation {
 	return collations