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375 lines
10 KiB
375 lines
10 KiB
// Copyright 2016 PingCAP, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package tables
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import (
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"context"
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"io"
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"github.com/opentracing/opentracing-go"
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"github.com/pingcap/errors"
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"github.com/pingcap/parser/model"
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"github.com/pingcap/parser/mysql"
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"github.com/pingcap/tidb/kv"
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"github.com/pingcap/tidb/sessionctx"
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"github.com/pingcap/tidb/sessionctx/stmtctx"
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"github.com/pingcap/tidb/table"
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"github.com/pingcap/tidb/tablecodec"
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"github.com/pingcap/tidb/types"
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"github.com/pingcap/tidb/util/codec"
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)
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// indexIter is for KV store index iterator.
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type indexIter struct {
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it kv.Iterator
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idx *index
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prefix kv.Key
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}
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// Close does the clean up works when KV store index iterator is closed.
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func (c *indexIter) Close() {
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if c.it != nil {
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c.it.Close()
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c.it = nil
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}
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}
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// Next returns current key and moves iterator to the next step.
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func (c *indexIter) Next() (val []types.Datum, h int64, err error) {
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if !c.it.Valid() {
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return nil, 0, errors.Trace(io.EOF)
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}
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if !c.it.Key().HasPrefix(c.prefix) {
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return nil, 0, errors.Trace(io.EOF)
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}
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// get indexedValues
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buf := c.it.Key()[len(c.prefix):]
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vv, err := codec.Decode(buf, len(c.idx.idxInfo.Columns))
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if err != nil {
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return nil, 0, err
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}
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if len(vv) > len(c.idx.idxInfo.Columns) {
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h = vv[len(vv)-1].GetInt64()
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val = vv[0 : len(vv)-1]
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} else {
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// If the index is unique and the value isn't nil, the handle is in value.
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h, err = tablecodec.DecodeHandle(c.it.Value())
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if err != nil {
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return nil, 0, err
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}
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val = vv
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}
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// update new iter to next
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err = c.it.Next()
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if err != nil {
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return nil, 0, err
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}
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return
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}
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// index is the data structure for index data in the KV store.
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type index struct {
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idxInfo *model.IndexInfo
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tblInfo *model.TableInfo
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prefix kv.Key
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containNonBinaryString bool
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phyTblID int64
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}
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// ContainsNonBinaryString checks whether the index columns contains non binary string column, the input
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// colInfos should be column info correspond to the table contains the index.
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func ContainsNonBinaryString(idxCols []*model.IndexColumn, colInfos []*model.ColumnInfo) bool {
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for _, idxCol := range idxCols {
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col := colInfos[idxCol.Offset]
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if col.EvalType() == types.ETString && !mysql.HasBinaryFlag(col.Flag) {
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return true
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}
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}
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return false
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}
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func (c *index) checkContainNonBinaryString() bool {
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return ContainsNonBinaryString(c.idxInfo.Columns, c.tblInfo.Columns)
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}
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// NewIndex builds a new Index object.
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func NewIndex(physicalID int64, tblInfo *model.TableInfo, indexInfo *model.IndexInfo) table.Index {
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index := &index{
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idxInfo: indexInfo,
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tblInfo: tblInfo,
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// The prefix can't encode from tblInfo.ID, because table partition may change the id to partition id.
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prefix: tablecodec.EncodeTableIndexPrefix(physicalID, indexInfo.ID),
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phyTblID: physicalID,
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}
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index.containNonBinaryString = index.checkContainNonBinaryString()
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return index
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}
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// Meta returns index info.
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func (c *index) Meta() *model.IndexInfo {
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return c.idxInfo
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}
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// GenIndexKey generates storage key for index values. Returned distinct indicates whether the
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// indexed values should be distinct in storage (i.e. whether handle is encoded in the key).
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func (c *index) GenIndexKey(sc *stmtctx.StatementContext, indexedValues []types.Datum, h int64, buf []byte) (key []byte, distinct bool, err error) {
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return tablecodec.GenIndexKey(sc, c.tblInfo, c.idxInfo, c.phyTblID, indexedValues, h, buf)
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}
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// Create creates a new entry in the kvIndex data.
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// If the index is unique and there is an existing entry with the same key,
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// Create will return the existing entry's handle as the first return value, ErrKeyExists as the second return value.
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// Value layout:
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//
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// +--With Restore Data(for indices on string columns)
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// | |
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// | +--Non Unique (TailLen = len(PaddingData) + len(Flag), TailLen < 8 always)
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// | | |
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// | | +--Without Untouched Flag:
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// | | |
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// | | | Layout: TailLen | RestoreData | PaddingData
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// | | | Length: 1 | size(RestoreData) | size(paddingData)
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// | | |
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// | | | The length >= 10 always because of padding.
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// | | |
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// | | +--With Untouched Flag:
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// | |
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// | | Layout: TailLen | RestoreData | PaddingData | Flag
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// | | Length: 1 | size(RestoreData) | size(paddingData) | 1
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// | |
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// | | The length >= 11 always because of padding.
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// | |
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// | +--Unique (TailLen = len(Handle) + len(Flag), TailLen == 8 || TailLen == 9)
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// | |
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// | +--Without Untouched Flag:
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// | |
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// | | Layout: 0x08 | RestoreData | Handle
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// | | Length: 1 | size(RestoreData) | 8
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// | |
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// | | The length >= 10 always since size(RestoreData) > 0.
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// | |
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// | +--With Untouched Flag:
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// |
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// | Layout: 0x09 | RestoreData | Handle | Flag
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// | Length: 1 | size(RestoreData) | 8 | 1
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// |
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// | The length >= 11 always since size(RestoreData) > 0.
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// |
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// +--Without Restore Data(same with old layout)
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// |
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// +--Non Unique
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// | |
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// | +--Without Untouched Flag:
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// | |
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// | | Layout: '0'
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// | | Length: 1
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// | |
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// | +--With Untouched Flag:
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// |
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// | Layout: Flag
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// | Length: 1
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// |
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// +--Unique
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// |
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// +--Without Untouched Flag:
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// |
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// | Layout: Handle
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// | Length: 8
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// |
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// +--With Untouched Flag:
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//
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// Layout: Handle | Flag
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// Length: 8 | 1
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func (c *index) Create(sctx sessionctx.Context, rm kv.RetrieverMutator, indexedValues []types.Datum, h int64, opts ...table.CreateIdxOptFunc) (int64, error) {
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var opt table.CreateIdxOpt
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for _, fn := range opts {
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fn(&opt)
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}
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vars := sctx.GetSessionVars()
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writeBufs := vars.GetWriteStmtBufs()
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skipCheck := vars.StmtCtx.BatchCheck
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key, distinct, err := c.GenIndexKey(vars.StmtCtx, indexedValues, h, writeBufs.IndexKeyBuf)
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if err != nil {
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return 0, err
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}
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ctx := opt.Ctx
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if opt.Untouched {
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txn, err1 := sctx.Txn(true)
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if err1 != nil {
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return 0, err1
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}
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// If the index kv was untouched(unchanged), and the key/value already exists in mem-buffer,
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// should not overwrite the key with un-commit flag.
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// So if the key exists, just do nothing and return.
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_, err = txn.GetMemBuffer().Get(ctx, key)
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if err == nil {
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return 0, nil
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}
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}
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// save the key buffer to reuse.
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writeBufs.IndexKeyBuf = key
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var idxVal []byte
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idxVal, err = tablecodec.GenIndexValue(sctx.GetSessionVars().StmtCtx, c.tblInfo, c.idxInfo,
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c.containNonBinaryString, distinct, opt.Untouched, indexedValues, h)
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if err != nil {
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return 0, err
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}
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if !distinct || skipCheck || opt.Untouched {
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err = rm.Set(key, idxVal)
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return 0, err
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}
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if ctx != nil {
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if span := opentracing.SpanFromContext(ctx); span != nil && span.Tracer() != nil {
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span1 := span.Tracer().StartSpan("index.Create", opentracing.ChildOf(span.Context()))
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defer span1.Finish()
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ctx = opentracing.ContextWithSpan(ctx, span1)
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}
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} else {
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ctx = context.TODO()
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}
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value, err := rm.Get(ctx, key)
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if err != nil {
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if kv.IsErrNotFound(err) {
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err = rm.Set(key, idxVal)
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return 0, err
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}
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return 0, err
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}
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handle, err := tablecodec.DecodeHandle(value)
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if err != nil {
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return 0, err
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}
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return handle, kv.ErrKeyExists
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}
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// Delete removes the entry for handle h and indexedValues from KV index.
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func (c *index) Delete(sc *stmtctx.StatementContext, m kv.MemBuffer, indexedValues []types.Datum, h int64) error {
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key, distinct, err := c.GenIndexKey(sc, indexedValues, h, nil)
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if err != nil {
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return err
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}
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if distinct {
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err = m.DeleteWithNeedLock(key)
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} else {
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err = m.Delete(key)
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}
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return err
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}
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// Drop removes the KV index from store.
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func (c *index) Drop(rm kv.RetrieverMutator) error {
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it, err := rm.Iter(c.prefix, c.prefix.PrefixNext())
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if err != nil {
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return err
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}
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defer it.Close()
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// remove all indices
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for it.Valid() {
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if !it.Key().HasPrefix(c.prefix) {
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break
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}
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err := rm.Delete(it.Key())
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if err != nil {
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return err
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}
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err = it.Next()
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if err != nil {
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return err
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}
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}
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return nil
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}
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// Seek searches KV index for the entry with indexedValues.
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func (c *index) Seek(sc *stmtctx.StatementContext, r kv.Retriever, indexedValues []types.Datum) (iter table.IndexIterator, hit bool, err error) {
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key, _, err := c.GenIndexKey(sc, indexedValues, 0, nil)
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if err != nil {
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return nil, false, err
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}
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upperBound := c.prefix.PrefixNext()
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it, err := r.Iter(key, upperBound)
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if err != nil {
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return nil, false, err
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}
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// check if hit
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hit = false
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if it.Valid() && it.Key().Cmp(key) == 0 {
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hit = true
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}
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return &indexIter{it: it, idx: c, prefix: c.prefix}, hit, nil
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}
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// SeekFirst returns an iterator which points to the first entry of the KV index.
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func (c *index) SeekFirst(r kv.Retriever) (iter table.IndexIterator, err error) {
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upperBound := c.prefix.PrefixNext()
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it, err := r.Iter(c.prefix, upperBound)
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if err != nil {
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return nil, err
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}
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return &indexIter{it: it, idx: c, prefix: c.prefix}, nil
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}
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func (c *index) Exist(sc *stmtctx.StatementContext, rm kv.RetrieverMutator, indexedValues []types.Datum, h int64) (bool, int64, error) {
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key, distinct, err := c.GenIndexKey(sc, indexedValues, h, nil)
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if err != nil {
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return false, 0, err
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}
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value, err := rm.Get(context.TODO(), key)
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if kv.IsErrNotFound(err) {
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return false, 0, nil
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}
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if err != nil {
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return false, 0, err
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}
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// For distinct index, the value of key is handle.
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if distinct {
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handle, err := tablecodec.DecodeHandle(value)
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if err != nil {
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return false, 0, err
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}
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if handle != h {
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return true, handle, kv.ErrKeyExists
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}
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return true, handle, nil
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}
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return true, h, nil
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}
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func (c *index) FetchValues(r []types.Datum, vals []types.Datum) ([]types.Datum, error) {
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needLength := len(c.idxInfo.Columns)
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if vals == nil || cap(vals) < needLength {
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vals = make([]types.Datum, needLength)
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}
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vals = vals[:needLength]
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for i, ic := range c.idxInfo.Columns {
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if ic.Offset < 0 || ic.Offset >= len(r) {
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return nil, table.ErrIndexOutBound.GenWithStackByArgs(ic.Name, ic.Offset, r)
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}
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vals[i] = r[ic.Offset]
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}
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return vals, nil
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}
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