add improved collation support (broken)

README.md

@@ -143,6 +143,22 @@ Default:        none
 
 Sets the charset used for client-server interaction (`"SET NAMES <value>"`). If multiple charsets are set (separated by a comma), the following charset is used if setting the charset failes. This enables support for `utf8mb4` ([introduced in MySQL 5.5.3](http://dev.mysql.com/doc/refman/5.5/en/charset-unicode-utf8mb4.html)) with fallback to `utf8` for older servers (`charset=utf8mb4,utf8`).
 
+*Please note:*
+
+Usage of the `charset` parameter is discouraged because it issues queries.
+Unless you need the fallback behavior, please use `collation` instead.
+
+##### `collation`
+
+```
+Type:           string
+Valid Values:   <name>
+Default:        utf8_general_ci
+```
+
+Sets the collation used for client-server interaction on connection. In contrast to `charset`, `collation` does not issue queries. If the specified collation is unavailable on the target server, the connection will fail.
+
+A list of valid charsets for a server is retrievable with `SHOW COLLATION`.
 
 ##### `clientFoundRows`
 

collations.go

@@ -0,0 +1,238 @@
+// Go MySQL Driver - A MySQL-Driver for Go's database/sql package
+//
+// Copyright 2014 The Go-MySQL-Driver Authors. All rights reserved.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package mysql
+
+const collationUtf8GeneralCi = 33
+
+const defaultCollation byte = collationUtf8GeneralCi
+
+// A list of available collations and associated charsets to update this map
+// is available in MySQL with the query
+//     SELECT COLLATION_NAME, ID FROM information_schema.COLLATIONS
+var collations = map[string]byte{
+	"big5_chinese_ci":          1,
+	"latin2_czech_cs":          2,
+	"dec8_swedish_ci":          3,
+	"cp850_general_ci":         4,
+	"latin1_german1_ci":        5,
+	"hp8_english_ci":           6,
+	"koi8r_general_ci":         7,
+	"latin1_swedish_ci":        8,
+	"latin2_general_ci":        9,
+	"swe7_swedish_ci":          10,
+	"ascii_general_ci":         11,
+	"ujis_japanese_ci":         12,
+	"sjis_japanese_ci":         13,
+	"cp1251_bulgarian_ci":      14,
+	"latin1_danish_ci":         15,
+	"hebrew_general_ci":        16,
+	"tis620_thai_ci":           18,
+	"euckr_korean_ci":          19,
+	"latin7_estonian_cs":       20,
+	"latin2_hungarian_ci":      21,
+	"koi8u_general_ci":         22,
+	"cp1251_ukrainian_ci":      23,
+	"gb2312_chinese_ci":        24,
+	"greek_general_ci":         25,
+	"cp1250_general_ci":        26,
+	"latin2_croatian_ci":       27,
+	"gbk_chinese_ci":           28,
+	"cp1257_lithuanian_ci":     29,
+	"latin5_turkish_ci":        30,
+	"latin1_german2_ci":        31,
+	"armscii8_general_ci":      32,
+	"utf8_general_ci":          collationUtf8GeneralCi,
+	"cp1250_czech_cs":          34,
+	"ucs2_general_ci":          35,
+	"cp866_general_ci":         36,
+	"keybcs2_general_ci":       37,
+	"macce_general_ci":         38,
+	"macroman_general_ci":      39,
+	"cp852_general_ci":         40,
+	"latin7_general_ci":        41,
+	"latin7_general_cs":        42,
+	"macce_bin":                43,
+	"cp1250_croatian_ci":       44,
+	"utf8mb4_general_ci":       45,
+	"utf8mb4_bin":              46,
+	"latin1_bin":               47,
+	"latin1_general_ci":        48,
+	"latin1_general_cs":        49,
+	"cp1251_bin":               50,
+	"cp1251_general_ci":        51,
+	"cp1251_general_cs":        52,
+	"macroman_bin":             53,
+	"utf16_general_ci":         54,
+	"utf16_bin":                55,
+	"utf16le_general_ci":       56,
+	"cp1256_general_ci":        57,
+	"cp1257_bin":               58,
+	"cp1257_general_ci":        59,
+	"utf32_general_ci":         60,
+	"utf32_bin":                61,
+	"utf16le_bin":              62,
+	"binary":                   63,
+	"armscii8_bin":             64,
+	"ascii_bin":                65,
+	"cp1250_bin":               66,
+	"cp1256_bin":               67,
+	"cp866_bin":                68,
+	"dec8_bin":                 69,
+	"greek_bin":                70,
+	"hebrew_bin":               71,
+	"hp8_bin":                  72,
+	"keybcs2_bin":              73,
+	"koi8r_bin":                74,
+	"koi8u_bin":                75,
+	"latin2_bin":               77,
+	"latin5_bin":               78,
+	"latin7_bin":               79,
+	"cp850_bin":                80,
+	"cp852_bin":                81,
+	"swe7_bin":                 82,
+	"utf8_bin":                 83,
+	"big5_bin":                 84,
+	"euckr_bin":                85,
+	"gb2312_bin":               86,
+	"gbk_bin":                  87,
+	"sjis_bin":                 88,
+	"tis620_bin":               89,
+	"ucs2_bin":                 90,
+	"ujis_bin":                 91,
+	"geostd8_general_ci":       92,
+	"geostd8_bin":              93,
+	"latin1_spanish_ci":        94,
+	"cp932_japanese_ci":        95,
+	"cp932_bin":                96,
+	"eucjpms_japanese_ci":      97,
+	"eucjpms_bin":              98,
+	"cp1250_polish_ci":         99,
+	"utf16_unicode_ci":         101,
+	"utf16_icelandic_ci":       102,
+	"utf16_latvian_ci":         103,
+	"utf16_romanian_ci":        104,
+	"utf16_slovenian_ci":       105,
+	"utf16_polish_ci":          106,
+	"utf16_estonian_ci":        107,
+	"utf16_spanish_ci":         108,
+	"utf16_swedish_ci":         109,
+	"utf16_turkish_ci":         110,
+	"utf16_czech_ci":           111,
+	"utf16_danish_ci":          112,
+	"utf16_lithuanian_ci":      113,
+	"utf16_slovak_ci":          114,
+	"utf16_spanish2_ci":        115,
+	"utf16_roman_ci":           116,
+	"utf16_persian_ci":         117,
+	"utf16_esperanto_ci":       118,
+	"utf16_hungarian_ci":       119,
+	"utf16_sinhala_ci":         120,
+	"utf16_german2_ci":         121,
+	"utf16_croatian_ci":        122,
+	"utf16_unicode_520_ci":     123,
+	"utf16_vietnamese_ci":      124,
+	"ucs2_unicode_ci":          128,
+	"ucs2_icelandic_ci":        129,
+	"ucs2_latvian_ci":          130,
+	"ucs2_romanian_ci":         131,
+	"ucs2_slovenian_ci":        132,
+	"ucs2_polish_ci":           133,
+	"ucs2_estonian_ci":         134,
+	"ucs2_spanish_ci":          135,
+	"ucs2_swedish_ci":          136,
+	"ucs2_turkish_ci":          137,
+	"ucs2_czech_ci":            138,
+	"ucs2_danish_ci":           139,
+	"ucs2_lithuanian_ci":       140,
+	"ucs2_slovak_ci":           141,
+	"ucs2_spanish2_ci":         142,
+	"ucs2_roman_ci":            143,
+	"ucs2_persian_ci":          144,
+	"ucs2_esperanto_ci":        145,
+	"ucs2_hungarian_ci":        146,
+	"ucs2_sinhala_ci":          147,
+	"ucs2_german2_ci":          148,
+	"ucs2_croatian_ci":         149,
+	"ucs2_unicode_520_ci":      150,
+	"ucs2_vietnamese_ci":       151,
+	"ucs2_general_mysql500_ci": 159,
+	"utf32_unicode_ci":         160,
+	"utf32_icelandic_ci":       161,
+	"utf32_latvian_ci":         162,
+	"utf32_romanian_ci":        163,
+	"utf32_slovenian_ci":       164,
+	"utf32_polish_ci":          165,
+	"utf32_estonian_ci":        166,
+	"utf32_spanish_ci":         167,
+	"utf32_swedish_ci":         168,
+	"utf32_turkish_ci":         169,
+	"utf32_czech_ci":           170,
+	"utf32_danish_ci":          171,
+	"utf32_lithuanian_ci":      172,
+	"utf32_slovak_ci":          173,
+	"utf32_spanish2_ci":        174,
+	"utf32_roman_ci":           175,
+	"utf32_persian_ci":         176,
+	"utf32_esperanto_ci":       177,
+	"utf32_hungarian_ci":       178,
+	"utf32_sinhala_ci":         179,
+	"utf32_german2_ci":         180,
+	"utf32_croatian_ci":        181,
+	"utf32_unicode_520_ci":     182,
+	"utf32_vietnamese_ci":      183,
+	"utf8_unicode_ci":          192,
+	"utf8_icelandic_ci":        193,
+	"utf8_latvian_ci":          194,
+	"utf8_romanian_ci":         195,
+	"utf8_slovenian_ci":        196,
+	"utf8_polish_ci":           197,
+	"utf8_estonian_ci":         198,
+	"utf8_spanish_ci":          199,
+	"utf8_swedish_ci":          200,
+	"utf8_turkish_ci":          201,
+	"utf8_czech_ci":            202,
+	"utf8_danish_ci":           203,
+	"utf8_lithuanian_ci":       204,
+	"utf8_slovak_ci":           205,
+	"utf8_spanish2_ci":         206,
+	"utf8_roman_ci":            207,
+	"utf8_persian_ci":          208,
+	"utf8_esperanto_ci":        209,
+	"utf8_hungarian_ci":        210,
+	"utf8_sinhala_ci":          211,
+	"utf8_german2_ci":          212,
+	"utf8_croatian_ci":         213,
+	"utf8_unicode_520_ci":      214,
+	"utf8_vietnamese_ci":       215,
+	"utf8_general_mysql500_ci": 223,
+	"utf8mb4_unicode_ci":       224,
+	"utf8mb4_icelandic_ci":     225,
+	"utf8mb4_latvian_ci":       226,
+	"utf8mb4_romanian_ci":      227,
+	"utf8mb4_slovenian_ci":     228,
+	"utf8mb4_polish_ci":        229,
+	"utf8mb4_estonian_ci":      230,
+	"utf8mb4_spanish_ci":       231,
+	"utf8mb4_swedish_ci":       232,
+	"utf8mb4_turkish_ci":       233,
+	"utf8mb4_czech_ci":         234,
+	"utf8mb4_danish_ci":        235,
+	"utf8mb4_lithuanian_ci":    236,
+	"utf8mb4_slovak_ci":        237,
+	"utf8mb4_spanish2_ci":      238,
+	"utf8mb4_roman_ci":         239,
+	"utf8mb4_persian_ci":       240,
+	"utf8mb4_esperanto_ci":     241,
+	"utf8mb4_hungarian_ci":     242,
+	"utf8mb4_sinhala_ci":       243,
+	"utf8mb4_german2_ci":       244,
+	"utf8mb4_croatian_ci":      245,
+	"utf8mb4_unicode_520_ci":   246,
+	"utf8mb4_vietnamese_ci":    247,
+}

connection.go

@@ -27,6 +27,7 @@ type mysqlConn struct {
 	maxWriteSize     int
 	flags            clientFlag
 	sequence         uint8
+	collation        byte
 	parseTime        bool
 	strict           bool
 }
@@ -50,6 +51,20 @@ type config struct {
 func (mc *mysqlConn) handleParams() (err error) {
 	for param, val := range mc.cfg.params {
 		switch param {
+		// Collation
+		case "collation":
+			collation, ok := collations[val]
+			if !ok {
+				// Note possibility for false negatives:
+				// could be caused although the collation is valid
+				// if the collations map does not contain entries
+				// the server supports.
+				err = errors.New("unknown collation")
+				return
+			}
+			mc.collation = collation
+			break
+
 		// Charset
 		case "charset":
 			charsets := strings.Split(val, ",")

const.go

@@ -130,13 +130,3 @@ const (
 	flagUnknown3
 	flagUnknown4
 )
-
-const (
-	collation_ascii_general_ci   byte = 11
-	collation_utf8_general_ci    byte = 33
-	collation_utf8mb4_general_ci byte = 45
-	collation_utf8mb4_bin        byte = 46
-	collation_latin1_general_ci  byte = 48
-	collation_binary             byte = 63
-	collation_utf8mb4_unicode_ci byte = 224
-)

driver.go

@@ -40,6 +40,7 @@ func (d *MySQLDriver) Open(dsn string) (driver.Conn, error) {
 	mc := &mysqlConn{
 		maxPacketAllowed: maxPacketSize,
 		maxWriteSize:     maxPacketSize - 1,
+		collation:        defaultCollation,
 	}
 	mc.cfg, err = parseDSN(dsn)
 	if err != nil {

driver_test.go

@@ -938,6 +938,49 @@ func TestFailingCharset(t *testing.T) {
 	})
 }
 
+func TestCollation(t *testing.T) {
+	if !available {
+		t.Skipf("MySQL-Server not running on %s", netAddr)
+	}
+
+	defaultCollation := "utf8_general_ci"
+	tests := []string{
+		"",               // do not set
+		defaultCollation, // driver default
+		"latin1_general_ci",
+		"binary",
+		"utf8mb4_general_ci",
+	}
+	cdsn := dsn
+	for _, collation := range tests {
+		var expected string
+		if collation != "" {
+			cdsn += "&collation=" + collation
+			expected = collation
+		} else {
+			expected = defaultCollation
+		}
+		runTests(t, cdsn, func(dbt *DBTest) {
+			rows := dbt.mustQuery("SELECT @@collation_connection")
+			defer rows.Close()
+
+			if !rows.Next() {
+				dbt.Fatalf("Error getting connection collation: %s", rows.Err())
+			}
+
+			var got string
+			err := rows.Scan(&got)
+			if err != nil {
+				dbt.Fatal(err)
+			}
+
+			if got != expected {
+				dbt.Fatalf("Expected connection collation %s but got %s", expected, got)
+			}
+		})
+	}
+}
+
 func TestRawBytesResultExceedsBuffer(t *testing.T) {
 	runTests(t, dsn, func(dbt *DBTest) {
 		// defaultBufSize from buffer.go

packets.go

@@ -257,7 +257,7 @@ func (mc *mysqlConn) writeAuthPacket(cipher []byte) error {
 	data[11] = 0x00
 
 	// Charset [1 byte]
-	data[12] = collation_utf8_general_ci
+	data[12] = mc.collation
 
 	// SSL Connection Request Packet
 	// http://dev.mysql.com/doc/internals/en/connection-phase-packets.html#packet-Protocol::SSLRequest