vitess.io/vitess@v0.16.2/go/mysql/charset.go (about)

     1  /*
     2  Copyright 2019 The Vitess Authors.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8      http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package mysql
    18  
    19  import (
    20  	"fmt"
    21  	"strconv"
    22  
    23  	binlogdatapb "vitess.io/vitess/go/vt/proto/binlogdata"
    24  	"vitess.io/vitess/go/vt/proto/vtrpc"
    25  	"vitess.io/vitess/go/vt/vterrors"
    26  )
    27  
    28  // This file contains utility methods for Conn objects. Only useful on the client
    29  // side.
    30  
    31  // ExecuteFetchMap returns a map from column names to cell data for a query
    32  // that should return exactly 1 row.
    33  func ExecuteFetchMap(conn *Conn, query string) (map[string]string, error) {
    34  	qr, err := conn.ExecuteFetch(query, 1, true)
    35  	if err != nil {
    36  		return nil, err
    37  	}
    38  	if len(qr.Rows) != 1 {
    39  		return nil, vterrors.Errorf(vtrpc.Code_OUT_OF_RANGE, "query %#v returned %d rows, expected 1", query, len(qr.Rows))
    40  	}
    41  	if len(qr.Fields) != len(qr.Rows[0]) {
    42  		return nil, vterrors.Errorf(vtrpc.Code_INTERNAL, "query %#v returned %d column names, expected %d", query, len(qr.Fields), len(qr.Rows[0]))
    43  	}
    44  
    45  	rowMap := make(map[string]string)
    46  	for i, value := range qr.Rows[0] {
    47  		rowMap[qr.Fields[i].Name] = value.ToString()
    48  	}
    49  	return rowMap, nil
    50  }
    51  
    52  // GetCharset returns the current numerical values of the per-session character
    53  // set variables.
    54  func GetCharset(conn *Conn) (*binlogdatapb.Charset, error) {
    55  	// character_set_client
    56  	row, err := ExecuteFetchMap(conn, "SHOW COLLATION WHERE `charset`=@@session.character_set_client AND `default`='Yes'")
    57  	if err != nil {
    58  		return nil, err
    59  	}
    60  	client, err := strconv.ParseInt(row["Id"], 10, 16)
    61  	if err != nil {
    62  		return nil, err
    63  	}
    64  
    65  	// collation_connection
    66  	row, err = ExecuteFetchMap(conn, "SHOW COLLATION WHERE `collation`=@@session.collation_connection")
    67  	if err != nil {
    68  		return nil, err
    69  	}
    70  	connection, err := strconv.ParseInt(row["Id"], 10, 16)
    71  	if err != nil {
    72  		return nil, err
    73  	}
    74  
    75  	// collation_server
    76  	row, err = ExecuteFetchMap(conn, "SHOW COLLATION WHERE `collation`=@@session.collation_server")
    77  	if err != nil {
    78  		return nil, err
    79  	}
    80  	server, err := strconv.ParseInt(row["Id"], 10, 16)
    81  	if err != nil {
    82  		return nil, err
    83  	}
    84  
    85  	return &binlogdatapb.Charset{
    86  		Client: int32(client),
    87  		Conn:   int32(connection),
    88  		Server: int32(server),
    89  	}, nil
    90  }
    91  
    92  // SetCharset changes the per-session character set variables.
    93  func SetCharset(conn *Conn, cs *binlogdatapb.Charset) error {
    94  	sql := fmt.Sprintf(
    95  		"SET @@session.character_set_client=%d, @@session.collation_connection=%d, @@session.collation_server=%d",
    96  		cs.Client, cs.Conn, cs.Server)
    97  	_, err := conn.ExecuteFetch(sql, 1, false)
    98  	return err
    99  }