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