tidb rowindexcodec 源码
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
}
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