tidb rowindexcodec 代码
文件路径：/tablecodec/rowindexcodec/rowindexcodec.go
/ Copyright 2021 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 rowindexcodec
import (
"bytes"
)
/ KeyKind is a specific type of key, mainly used to distinguish row/index.
type KeyKind int
const (
/ KeyKindUnknown indicates that this key is unknown type.
KeyKindUnknown KeyKind = iota
/ KeyKindRow means that this key belongs to row.
KeyKindRow
/ KeyKindIndex means that this key belongs to index.
KeyKindIndex
)
var (
tablePrefix = []byte{'t'}
rowPrefix = []byte("_r")
indexPrefix = []byte("_i")
)
/ GetKeyKind returns the KeyKind that matches the key in the minimalist way.
func GetKeyKind(key []byte) KeyKind {
/ [ TABLE_PREFIX | TABLE_ID | ROW_PREFIX (INDEX_PREFIX) | ROW_ID (INDEX_ID) | ... ] (name)
/ [ 1 | 8 | 2 | 8 | ... ] (byte)
if len(key) < 11 {
return KeyKindUnknown
}
if !bytes.HasPrefix(key, tablePrefix) {
return KeyKindUnknown
}
key = key[9:]
if bytes.HasPrefix(key, rowPrefix) {
return KeyKindRow
}
if bytes.HasPrefix(key, indexPrefix) {
return KeyKindIndex
}
return KeyKindUnknown
}