tidb column 源码
tidb column 代码
文件路径：/server/column.go
// Copyright 2015 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package server
import (
"github.com/pingcap/tidb/parser/charset"
"github.com/pingcap/tidb/parser/mysql"
)
const maxColumnNameSize = 256
// ColumnInfo contains information of a column
type ColumnInfo struct {
Schema string
Table string
OrgTable string
Name string
OrgName string
ColumnLength uint32
Charset uint16
Flag uint16
Decimal uint8
Type uint8
DefaultValueLength uint64
DefaultValue []byte
}
// Dump dumps ColumnInfo to bytes.
func (column *ColumnInfo) Dump(buffer []byte, d *resultEncoder) []byte {
if d == nil {
d = newResultEncoder(charset.CharsetUTF8MB4)
}
nameDump, orgnameDump := []byte(column.Name), []byte(column.OrgName)
if len(nameDump) > maxColumnNameSize {
nameDump = nameDump[0:maxColumnNameSize]
}
if len(orgnameDump) > maxColumnNameSize {
orgnameDump = orgnameDump[0:maxColumnNameSize]
}
buffer = dumpLengthEncodedString(buffer, []byte("def"))
buffer = dumpLengthEncodedString(buffer, d.encodeMeta([]byte(column.Schema)))
buffer = dumpLengthEncodedString(buffer, d.encodeMeta([]byte(column.Table)))
buffer = dumpLengthEncodedString(buffer, d.encodeMeta([]byte(column.OrgTable)))
buffer = dumpLengthEncodedString(buffer, d.encodeMeta(nameDump))
buffer = dumpLengthEncodedString(buffer, d.encodeMeta(orgnameDump))
buffer = append(buffer, 0x0c)
buffer = dumpUint16(buffer, d.columnTypeInfoCharsetID(column))
buffer = dumpUint32(buffer, column.ColumnLength)
buffer = append(buffer, dumpType(column.Type))
buffer = dumpUint16(buffer, dumpFlag(column.Type, column.Flag))
buffer = append(buffer, column.Decimal)
buffer = append(buffer, 0, 0)
if column.DefaultValue != nil {
buffer = dumpUint64(buffer, uint64(len(column.DefaultValue)))
buffer = append(buffer, column.DefaultValue...)
}
return buffer
}
func isStringColumnType(tp byte) bool {
switch tp {
case mysql.TypeString, mysql.TypeVarString, mysql.TypeVarchar, mysql.TypeBit,
mysql.TypeTinyBlob, mysql.TypeMediumBlob, mysql.TypeLongBlob, mysql.TypeBlob,
mysql.TypeEnum, mysql.TypeSet, mysql.TypeJSON:
return true
}
return false
}
func dumpFlag(tp byte, flag uint16) uint16 {
switch tp {
case mysql.TypeSet:
return flag | uint16(mysql.SetFlag)
case mysql.TypeEnum:
return flag | uint16(mysql.EnumFlag)
default:
return flag
}
}
func dumpType(tp byte) byte {
switch tp {
case mysql.TypeSet, mysql.TypeEnum:
return mysql.TypeString
default:
return tp
}
}
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