partition.go

// Copyright 2018 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 tables

import (
	"bytes"
	"context"
	stderr "errors"
	"fmt"
	"hash/crc32"
	"sort"
	"strconv"
	"strings"
	"sync"

	"github.com/google/btree"
	"github.com/pingcap/errors"
	"github.com/pingcap/tidb/pkg/errctx"
	"github.com/pingcap/tidb/pkg/expression"
	"github.com/pingcap/tidb/pkg/expression/contextstatic"
	"github.com/pingcap/tidb/pkg/kv"
	"github.com/pingcap/tidb/pkg/parser"
	"github.com/pingcap/tidb/pkg/parser/ast"
	"github.com/pingcap/tidb/pkg/parser/model"
	"github.com/pingcap/tidb/pkg/parser/mysql"
	"github.com/pingcap/tidb/pkg/sessionctx/variable"
	"github.com/pingcap/tidb/pkg/table"
	"github.com/pingcap/tidb/pkg/tablecodec"
	"github.com/pingcap/tidb/pkg/types"
	"github.com/pingcap/tidb/pkg/util"
	"github.com/pingcap/tidb/pkg/util/chunk"
	"github.com/pingcap/tidb/pkg/util/codec"
	"github.com/pingcap/tidb/pkg/util/dbterror"
	"github.com/pingcap/tidb/pkg/util/hack"
	"github.com/pingcap/tidb/pkg/util/logutil"
	"github.com/pingcap/tidb/pkg/util/ranger"
	"github.com/pingcap/tidb/pkg/util/stringutil"
	"go.uber.org/zap"
)

const (
	btreeDegree = 32
)

// Both partition and partitionedTable implement the table.Table interface.
var _ table.PhysicalTable = &partition{}
var _ table.Table = &partitionedTable{}

// partitionedTable implements the table.PartitionedTable interface.
var _ table.PartitionedTable = &partitionedTable{}

// partition is a feature from MySQL:
// See https://dev.mysql.com/doc/refman/8.0/en/partitioning.html
// A partition table may contain many partitions, each partition has a unique partition
// id. The underlying representation of a partition and a normal table (a table with no
// partitions) is basically the same.
// partition also implements the table.Table interface.
type partition struct {
	TableCommon
	table *partitionedTable
}

// GetPhysicalID implements table.Table GetPhysicalID interface.
func (p *partition) GetPhysicalID() int64 {
	return p.physicalTableID
}

// GetPartitionedTable implements table.Table GetPartitionedTable interface.
func (p *partition) GetPartitionedTable() table.PartitionedTable {
	return p.table
}

// GetPartitionedTable implements table.Table GetPartitionedTable interface.
func (t *partitionedTable) GetPartitionedTable() table.PartitionedTable {
	return t
}

// partitionedTable implements the table.PartitionedTable interface.
// partitionedTable is a table, it contains many Partitions.
type partitionedTable struct {
	TableCommon
	partitionExpr   *PartitionExpr
	partitions      map[int64]*partition
	evalBufferTypes []*types.FieldType
	evalBufferPool  sync.Pool

	// Only used during Reorganize partition
	// reorganizePartitions is the currently used partitions that are reorganized
	reorganizePartitions map[int64]any
	// doubleWritePartitions are the partitions not visible, but we should double write to
	doubleWritePartitions map[int64]any
	reorgPartitionExpr    *PartitionExpr
}

// TODO: Check which data structures that can be shared between all partitions and which
// needs to be copies
func newPartitionedTable(tbl *TableCommon, tblInfo *model.TableInfo) (table.PartitionedTable, error) {
	pi := tblInfo.GetPartitionInfo()
	if pi == nil || len(pi.Definitions) == 0 {
		return nil, table.ErrUnknownPartition
	}
	ret := &partitionedTable{TableCommon: tbl.Copy()}
	partitionExpr, err := newPartitionExpr(tblInfo, pi.Type, pi.Expr, pi.Columns, pi.Definitions)
	if err != nil {
		return nil, errors.Trace(err)
	}
	ret.partitionExpr = partitionExpr
	initEvalBufferType(ret)
	ret.evalBufferPool = sync.Pool{
		New: func() any {
			return initEvalBuffer(ret)
		},
	}
	if err := initTableIndices(&ret.TableCommon); err != nil {
		return nil, errors.Trace(err)
	}
	partitions := make(map[int64]*partition, len(pi.Definitions))
	for _, p := range pi.Definitions {
		var t partition
		err := initTableCommonWithIndices(&t.TableCommon, tblInfo, p.ID, tbl.Columns, tbl.allocs, tbl.Constraints)
		if err != nil {
			return nil, errors.Trace(err)
		}
		t.table = ret
		partitions[p.ID] = &t
	}
	ret.partitions = partitions
	// In StateWriteReorganization we are using the 'old' partition definitions
	// and if any new change happens in DroppingDefinitions, it needs to be done
	// also in AddingDefinitions (with new evaluation of the new expression)
	// In StateDeleteReorganization we are using the 'new' partition definitions
	// and if any new change happens in AddingDefinitions, it needs to be done
	// also in DroppingDefinitions (since session running on schema version -1)
	// should also see the changes
	if pi.DDLState == model.StateDeleteReorganization {
		origIdx := setIndexesState(ret, pi.DDLState)
		defer unsetIndexesState(ret, origIdx)
		// TODO: Explicitly explain the different DDL/New fields!
		if pi.NewTableID != 0 {
			ret.reorgPartitionExpr, err = newPartitionExpr(tblInfo, pi.DDLType, pi.DDLExpr, pi.DDLColumns, pi.DroppingDefinitions)
		} else {
			ret.reorgPartitionExpr, err = newPartitionExpr(tblInfo, pi.Type, pi.Expr, pi.Columns, pi.DroppingDefinitions)
		}
		if err != nil {
			return nil, errors.Trace(err)
		}
		ret.reorganizePartitions = make(map[int64]any, len(pi.AddingDefinitions))
		for _, def := range pi.AddingDefinitions {
			ret.reorganizePartitions[def.ID] = nil
		}
		ret.doubleWritePartitions = make(map[int64]any, len(pi.DroppingDefinitions))
		for _, def := range pi.DroppingDefinitions {
			p, err := initPartition(ret, def)
			if err != nil {
				return nil, err
			}
			partitions[def.ID] = p
			ret.doubleWritePartitions[def.ID] = nil
		}
	} else {
		if len(pi.AddingDefinitions) > 0 {
			origIdx := setIndexesState(ret, pi.DDLState)
			defer unsetIndexesState(ret, origIdx)
			if pi.NewTableID != 0 {
				// REMOVE PARTITIONING or PARTITION BY
				ret.reorgPartitionExpr, err = newPartitionExpr(tblInfo, pi.DDLType, pi.DDLExpr, pi.DDLColumns, pi.AddingDefinitions)
			} else {
				// REORGANIZE PARTITION
				ret.reorgPartitionExpr, err = newPartitionExpr(tblInfo, pi.Type, pi.Expr, pi.Columns, pi.AddingDefinitions)
			}
			if err != nil {
				return nil, errors.Trace(err)
			}
			ret.doubleWritePartitions = make(map[int64]any, len(pi.AddingDefinitions))
			for _, def := range pi.AddingDefinitions {
				ret.doubleWritePartitions[def.ID] = nil
				p, err := initPartition(ret, def)
				if err != nil {
					return nil, err
				}
				partitions[def.ID] = p
			}
		}
		if len(pi.DroppingDefinitions) > 0 {
			ret.reorganizePartitions = make(map[int64]any, len(pi.DroppingDefinitions))
			for _, def := range pi.DroppingDefinitions {
				ret.reorganizePartitions[def.ID] = nil
			}
		}
	}
	return ret, nil
}

func setIndexesState(t *partitionedTable, state model.SchemaState) []*model.IndexInfo {
	orig := t.meta.Indices
	t.meta.Indices = make([]*model.IndexInfo, 0, len(orig))
	for i := range orig {
		t.meta.Indices = append(t.meta.Indices, orig[i].Clone())
		if t.meta.Indices[i].State == model.StatePublic {
			switch state {
			case model.StateDeleteOnly, model.StateNone:
				t.meta.Indices[i].State = model.StateDeleteOnly
			case model.StatePublic:
				// Keep as is
			default:
				// use the 'StateWriteReorganization' here, since StateDeleteReorganization
				// would skip index writes.
				t.meta.Indices[i].State = model.StateWriteReorganization
			}
		}
	}
	return orig
}

func unsetIndexesState(t *partitionedTable, orig []*model.IndexInfo) {
	t.meta.Indices = orig
}

func initPartition(t *partitionedTable, def model.PartitionDefinition) (*partition, error) {
	var newPart partition
	err := initTableCommonWithIndices(&newPart.TableCommon, t.meta, def.ID, t.Columns, t.allocs, t.Constraints)
	if err != nil {
		return nil, err
	}
	newPart.table = t
	return &newPart, nil
}

// NewPartitionExprBuildCtx returns a context to build partition expression.
func NewPartitionExprBuildCtx() expression.BuildContext {
	return contextstatic.NewStaticExprContext(
		contextstatic.WithEvalCtx(contextstatic.NewStaticEvalContext(
			// Set a non-strict SQL mode and allow all date values if possible to make sure constant fold can work to
			// estimate some undetermined result when locating a row to a partition.
			// See issue: https://github.com/pingcap/tidb/issues/54271 for details.
			contextstatic.WithSQLMode(mysql.ModeAllowInvalidDates),
			contextstatic.WithTypeFlags(types.StrictFlags.
				WithIgnoreTruncateErr(true).
				WithIgnoreZeroDateErr(true).
				WithIgnoreZeroInDate(true).
				WithIgnoreInvalidDateErr(true),
			),
			contextstatic.WithErrLevelMap(errctx.LevelMap{
				errctx.ErrGroupTruncate: errctx.LevelIgnore,
			}),
		)),
	)
}

func newPartitionExpr(tblInfo *model.TableInfo, tp model.PartitionType, expr string, partCols []model.CIStr, defs []model.PartitionDefinition) (*PartitionExpr, error) {
	ctx := NewPartitionExprBuildCtx()
	dbName := model.NewCIStr(ctx.GetEvalCtx().CurrentDB())
	columns, names, err := expression.ColumnInfos2ColumnsAndNames(ctx, dbName, tblInfo.Name, tblInfo.Cols(), tblInfo)
	if err != nil {
		return nil, err
	}
	switch tp {
	case model.PartitionTypeNone:
		// Nothing to do
		return nil, nil
	case model.PartitionTypeRange:
		return generateRangePartitionExpr(ctx, expr, partCols, defs, columns, names)
	case model.PartitionTypeHash:
		return generateHashPartitionExpr(ctx, expr, columns, names)
	case model.PartitionTypeKey:
		return generateKeyPartitionExpr(ctx, expr, partCols, columns, names)
	case model.PartitionTypeList:
		return generateListPartitionExpr(ctx, tblInfo, expr, partCols, defs, columns, names)
	}
	panic("cannot reach here")
}

// PartitionExpr is the partition definition expressions.
type PartitionExpr struct {
	// UpperBounds: (x < y1); (x < y2); (x < y3), used by locatePartition.
	UpperBounds []expression.Expression
	// OrigExpr is the partition expression ast used in point get.
	OrigExpr ast.ExprNode
	// Expr is the hash partition expression.
	Expr expression.Expression
	// Used in the key partition
	*ForKeyPruning
	// Used in the range pruning process.
	*ForRangePruning
	// Used in the range column pruning process.
	*ForRangeColumnsPruning
	// ColOffset is the offsets of partition columns.
	ColumnOffset []int
	*ForListPruning
}

// GetPartColumnsForKeyPartition is used to get partition columns for key partition table
func (pe *PartitionExpr) GetPartColumnsForKeyPartition(columns []*expression.Column) ([]*expression.Column, []int) {
	schema := expression.NewSchema(columns...)
	partCols := make([]*expression.Column, len(pe.ColumnOffset))
	colLen := make([]int, 0, len(pe.ColumnOffset))
	for i, offset := range pe.ColumnOffset {
		partCols[i] = schema.Columns[offset]
		partCols[i].Index = i
		colLen = append(colLen, partCols[i].RetType.GetFlen())
	}
	return partCols, colLen
}

// LocateKeyPartition is the common interface used to locate the destination partition
func (kp *ForKeyPruning) LocateKeyPartition(numParts uint64, r []types.Datum) (int, error) {
	h := crc32.NewIEEE()
	for _, col := range kp.KeyPartCols {
		val := r[col.Index]
		if val.Kind() == types.KindNull {
			h.Write([]byte{0})
		} else {
			data, err := val.ToHashKey()
			if err != nil {
				return 0, err
			}
			h.Write(data)
		}
	}
	return int(h.Sum32() % uint32(numParts)), nil
}

func initEvalBufferType(t *partitionedTable) {
	hasExtraHandle := false
	numCols := len(t.Cols())
	if !t.Meta().PKIsHandle {
		hasExtraHandle = true
		numCols++
	}
	t.evalBufferTypes = make([]*types.FieldType, numCols)
	for i, col := range t.Cols() {
		t.evalBufferTypes[i] = &col.FieldType
	}

	if hasExtraHandle {
		t.evalBufferTypes[len(t.evalBufferTypes)-1] = types.NewFieldType(mysql.TypeLonglong)
	}
}

func initEvalBuffer(t *partitionedTable) *chunk.MutRow {
	evalBuffer := chunk.MutRowFromTypes(t.evalBufferTypes)
	return &evalBuffer
}

// ForRangeColumnsPruning is used for range partition pruning.
type ForRangeColumnsPruning struct {
	// LessThan contains expressions for [Partition][column].
	// If Maxvalue, then nil
	LessThan [][]*expression.Expression
}

func dataForRangeColumnsPruning(ctx expression.BuildContext, defs []model.PartitionDefinition, schema *expression.Schema, names []*types.FieldName, p *parser.Parser, colOffsets []int) (*ForRangeColumnsPruning, error) {
	var res ForRangeColumnsPruning
	res.LessThan = make([][]*expression.Expression, 0, len(defs))
	for i := 0; i < len(defs); i++ {
		lessThanCols := make([]*expression.Expression, 0, len(defs[i].LessThan))
		for j := range defs[i].LessThan {
			if strings.EqualFold(defs[i].LessThan[j], "MAXVALUE") {
				// Use a nil pointer instead of math.MaxInt64 to avoid the corner cases.
				lessThanCols = append(lessThanCols, nil)
				// No column after MAXVALUE matters
				break
			}
			tmp, err := parseSimpleExprWithNames(p, ctx, defs[i].LessThan[j], schema, names)
			if err != nil {
				return nil, err
			}
			_, ok := tmp.(*expression.Constant)
			if !ok {
				return nil, dbterror.ErrPartitionConstDomain
			}
			// TODO: Enable this for all types!
			// Currently it will trigger changes for collation differences
			switch schema.Columns[colOffsets[j]].RetType.GetType() {
			case mysql.TypeDatetime, mysql.TypeDate:
				// Will also fold constant
				tmp = expression.BuildCastFunction(ctx, tmp, schema.Columns[colOffsets[j]].RetType)
			}
			lessThanCols = append(lessThanCols, &tmp)
		}
		res.LessThan = append(res.LessThan, lessThanCols)
	}
	return &res, nil
}

// parseSimpleExprWithNames parses simple expression string to Expression.
// The expression string must only reference the column in the given NameSlice.
func parseSimpleExprWithNames(p *parser.Parser, ctx expression.BuildContext, exprStr string, schema *expression.Schema, names types.NameSlice) (expression.Expression, error) {
	exprNode, err := parseExpr(p, exprStr)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return expression.BuildSimpleExpr(ctx, exprNode, expression.WithInputSchemaAndNames(schema, names, nil))
}

// ForKeyPruning is used for key partition pruning.
type ForKeyPruning struct {
	KeyPartCols []*expression.Column
}

// ForListPruning is used for list partition pruning.
type ForListPruning struct {
	// LocateExpr uses to locate list partition by row.
	LocateExpr expression.Expression
	// PruneExpr uses to prune list partition in partition pruner.
	PruneExpr expression.Expression
	// PruneExprCols is the columns of PruneExpr, it has removed the duplicate columns.
	PruneExprCols []*expression.Column
	// valueMap is column value -> partition idx, uses to locate list partition.
	valueMap map[int64]int
	// nullPartitionIdx is the partition idx for null value.
	nullPartitionIdx int
	// defaultPartitionIdx is the partition idx for default value/fallback.
	defaultPartitionIdx int

	// For list columns partition pruning
	ColPrunes []*ForListColumnPruning
}

// btreeListColumnItem is BTree's Item that uses string to compare.
type btreeListColumnItem struct {
	key      string
	location ListPartitionLocation
}

func newBtreeListColumnItem(key string, location ListPartitionLocation) *btreeListColumnItem {
	return &btreeListColumnItem{
		key:      key,
		location: location,
	}
}

func newBtreeListColumnSearchItem(key string) *btreeListColumnItem {
	return &btreeListColumnItem{
		key: key,
	}
}

func (item *btreeListColumnItem) Less(other btree.Item) bool {
	return item.key < other.(*btreeListColumnItem).key
}

func lessBtreeListColumnItem(a, b *btreeListColumnItem) bool {
	return a.key < b.key
}

// ForListColumnPruning is used for list columns partition pruning.
type ForListColumnPruning struct {
	ExprCol  *expression.Column
	valueTp  *types.FieldType
	valueMap map[string]ListPartitionLocation
	sorted   *btree.BTreeG[*btreeListColumnItem]

	// To deal with the location partition failure caused by inconsistent NewCollationEnabled values(see issue #32416).
	// The following fields are used to delay building valueMap.
	ctx     expression.BuildContext
	tblInfo *model.TableInfo
	schema  *expression.Schema
	names   types.NameSlice
	colIdx  int

	// catch-all partition / DEFAULT
	defaultPartID int64
}

// ListPartitionGroup indicate the group index of the column value in a partition.
type ListPartitionGroup struct {
	// Such as: list columns (a,b) (partition p0 values in ((1,5),(1,6)));
	// For the column a which value is 1, the ListPartitionGroup is:
	// ListPartitionGroup {
	//     PartIdx: 0,            // 0 is the partition p0 index in all partitions.
	//     GroupIdxs: []int{0,1}, // p0 has 2 value group: (1,5) and (1,6), and they both contain the column a where value is 1;
	// }                          // the value of GroupIdxs `0,1` is the index of the value group that contain the column a which value is 1.
	PartIdx   int
	GroupIdxs []int
}

// ListPartitionLocation indicate the partition location for the column value in list columns partition.
// Here is an example:
// Suppose the list columns partition is: list columns (a,b) (partition p0 values in ((1,5),(1,6)), partition p1 values in ((1,7),(9,9)));
// How to express the location of the column a which value is 1?
// For the column a which value is 1, both partition p0 and p1 contain the column a which value is 1.
// In partition p0, both value group0 (1,5) and group1 (1,6) are contain the column a which value is 1.
// In partition p1, value group0 (1,7) contains the column a which value is 1.
// So, the ListPartitionLocation of column a which value is 1 is:
//
//	[]ListPartitionGroup{
//		{
//			PartIdx: 0,               // `0` is the partition p0 index in all partitions.
//			GroupIdxs: []int{0, 1}    // `0,1` is the index of the value group0, group1.
//		},
//		{
//			PartIdx: 1,               // `1` is the partition p1 index in all partitions.
//			GroupIdxs: []int{0}       // `0` is the index of the value group0.
//		},
//	}
type ListPartitionLocation []ListPartitionGroup

// IsEmpty returns true if the ListPartitionLocation is empty.
func (ps ListPartitionLocation) IsEmpty() bool {
	for _, pg := range ps {
		if len(pg.GroupIdxs) > 0 {
			return false
		}
	}
	return true
}

func (ps ListPartitionLocation) findByPartitionIdx(partIdx int) int {
	for i, p := range ps {
		if p.PartIdx == partIdx {
			return i
		}
	}
	return -1
}

type listPartitionLocationHelper struct {
	initialized bool
	location    ListPartitionLocation
}

// NewListPartitionLocationHelper returns a new listPartitionLocationHelper.
func NewListPartitionLocationHelper() *listPartitionLocationHelper {
	return &listPartitionLocationHelper{}
}

// GetLocation gets the list partition location.
func (p *listPartitionLocationHelper) GetLocation() ListPartitionLocation {
	return p.location
}

// UnionPartitionGroup unions with the list-partition-value-group.
func (p *listPartitionLocationHelper) UnionPartitionGroup(pg ListPartitionGroup) {
	idx := p.location.findByPartitionIdx(pg.PartIdx)
	if idx < 0 {
		// copy the group idx.
		groupIdxs := make([]int, len(pg.GroupIdxs))
		copy(groupIdxs, pg.GroupIdxs)
		p.location = append(p.location, ListPartitionGroup{
			PartIdx:   pg.PartIdx,
			GroupIdxs: groupIdxs,
		})
		return
	}
	p.location[idx].union(pg)
}

// Union unions with the other location.
func (p *listPartitionLocationHelper) Union(location ListPartitionLocation) {
	for _, pg := range location {
		p.UnionPartitionGroup(pg)
	}
}

// Intersect intersect with other location.
func (p *listPartitionLocationHelper) Intersect(location ListPartitionLocation) bool {
	if !p.initialized {
		p.initialized = true
		p.location = make([]ListPartitionGroup, 0, len(location))
		p.location = append(p.location, location...)
		return true
	}
	currPgs := p.location
	remainPgs := make([]ListPartitionGroup, 0, len(location))
	for _, pg := range location {
		idx := currPgs.findByPartitionIdx(pg.PartIdx)
		if idx < 0 {
			continue
		}
		if !currPgs[idx].intersect(pg) {
			continue
		}
		remainPgs = append(remainPgs, currPgs[idx])
	}
	p.location = remainPgs
	return len(remainPgs) > 0
}

func (pg *ListPartitionGroup) intersect(otherPg ListPartitionGroup) bool {
	if pg.PartIdx != otherPg.PartIdx {
		return false
	}
	var groupIdxs []int
	for _, gidx := range otherPg.GroupIdxs {
		if pg.findGroupIdx(gidx) {
			groupIdxs = append(groupIdxs, gidx)
		}
	}
	pg.GroupIdxs = groupIdxs
	return len(groupIdxs) > 0
}

func (pg *ListPartitionGroup) union(otherPg ListPartitionGroup) {
	if pg.PartIdx != otherPg.PartIdx {
		return
	}
	pg.GroupIdxs = append(pg.GroupIdxs, otherPg.GroupIdxs...)
}

func (pg *ListPartitionGroup) findGroupIdx(groupIdx int) bool {
	for _, gidx := range pg.GroupIdxs {
		if gidx == groupIdx {
			return true
		}
	}
	return false
}

// ForRangePruning is used for range partition pruning.
type ForRangePruning struct {
	LessThan []int64
	MaxValue bool
	Unsigned bool
}

// dataForRangePruning extracts the less than parts from 'partition p0 less than xx ... partition p1 less than ...'
func dataForRangePruning(sctx expression.BuildContext, defs []model.PartitionDefinition) (*ForRangePruning, error) {
	var maxValue bool
	var unsigned bool
	lessThan := make([]int64, len(defs))
	for i := 0; i < len(defs); i++ {
		if strings.EqualFold(defs[i].LessThan[0], "MAXVALUE") {
			// Use a bool flag instead of math.MaxInt64 to avoid the corner cases.
			maxValue = true
		} else {
			var err error
			lessThan[i], err = strconv.ParseInt(defs[i].LessThan[0], 10, 64)
			var numErr *strconv.NumError
			if stderr.As(err, &numErr) && numErr.Err == strconv.ErrRange {
				var tmp uint64
				tmp, err = strconv.ParseUint(defs[i].LessThan[0], 10, 64)
				lessThan[i] = int64(tmp)
				unsigned = true
			}
			if err != nil {
				val, ok := fixOldVersionPartitionInfo(sctx, defs[i].LessThan[0])
				if !ok {
					logutil.BgLogger().Error("wrong partition definition", zap.String("less than", defs[i].LessThan[0]))
					return nil, errors.WithStack(err)
				}
				lessThan[i] = val
			}
		}
	}
	return &ForRangePruning{
		LessThan: lessThan,
		MaxValue: maxValue,
		Unsigned: unsigned,
	}, nil
}

func fixOldVersionPartitionInfo(sctx expression.BuildContext, str string) (int64, bool) {
	// less than value should be calculate to integer before persistent.
	// Old version TiDB may not do it and store the raw expression.
	tmp, err := parseSimpleExprWithNames(parser.New(), sctx, str, nil, nil)
	if err != nil {
		return 0, false
	}
	ret, isNull, err := tmp.EvalInt(sctx.GetEvalCtx(), chunk.Row{})
	if err != nil || isNull {
		return 0, false
	}
	return ret, true
}

func rangePartitionExprStrings(cols []model.CIStr, expr string) []string {
	var s []string
	if len(cols) > 0 {
		s = make([]string, 0, len(cols))
		for _, col := range cols {
			s = append(s, stringutil.Escape(col.O, mysql.ModeNone))
		}
	} else {
		s = []string{expr}
	}
	return s
}

func generateKeyPartitionExpr(ctx expression.BuildContext, expr string, partCols []model.CIStr,
	columns []*expression.Column, names types.NameSlice) (*PartitionExpr, error) {
	ret := &PartitionExpr{
		ForKeyPruning: &ForKeyPruning{},
	}
	_, partColumns, offset, err := extractPartitionExprColumns(ctx, expr, partCols, columns, names)
	if err != nil {
		return nil, errors.Trace(err)
	}
	ret.ColumnOffset = offset
	ret.KeyPartCols = partColumns

	return ret, nil
}

func generateRangePartitionExpr(ctx expression.BuildContext, expr string, partCols []model.CIStr,
	defs []model.PartitionDefinition, columns []*expression.Column, names types.NameSlice) (*PartitionExpr, error) {
	// The caller should assure partition info is not nil.
	p := parser.New()
	schema := expression.NewSchema(columns...)
	partStrs := rangePartitionExprStrings(partCols, expr)
	locateExprs, err := getRangeLocateExprs(ctx, p, defs, partStrs, schema, names)
	if err != nil {
		return nil, errors.Trace(err)
	}
	ret := &PartitionExpr{
		UpperBounds: locateExprs,
	}

	partExpr, _, offset, err := extractPartitionExprColumns(ctx, expr, partCols, columns, names)
	if err != nil {
		return nil, errors.Trace(err)
	}
	ret.ColumnOffset = offset

	if len(partCols) < 1 {
		tmp, err := dataForRangePruning(ctx, defs)
		if err != nil {
			return nil, errors.Trace(err)
		}
		ret.Expr = partExpr
		ret.ForRangePruning = tmp
	} else {
		tmp, err := dataForRangeColumnsPruning(ctx, defs, schema, names, p, offset)
		if err != nil {
			return nil, errors.Trace(err)
		}
		ret.ForRangeColumnsPruning = tmp
	}
	return ret, nil
}

func getRangeLocateExprs(ctx expression.BuildContext, p *parser.Parser, defs []model.PartitionDefinition, partStrs []string, schema *expression.Schema, names types.NameSlice) ([]expression.Expression, error) {
	var buf bytes.Buffer
	locateExprs := make([]expression.Expression, 0, len(defs))
	for i := 0; i < len(defs); i++ {
		if strings.EqualFold(defs[i].LessThan[0], "MAXVALUE") {
			// Expr less than maxvalue is always true.
			fmt.Fprintf(&buf, "true")
		} else {
			maxValueFound := false
			for j := range partStrs[1:] {
				if strings.EqualFold(defs[i].LessThan[j+1], "MAXVALUE") {
					// if any column will be less than MAXVALUE, so change < to <= of the previous prefix of columns
					fmt.Fprintf(&buf, "((%s) <= (%s))", strings.Join(partStrs[:j+1], ","), strings.Join(defs[i].LessThan[:j+1], ","))
					maxValueFound = true
					break
				}
			}
			if !maxValueFound {
				fmt.Fprintf(&buf, "((%s) < (%s))", strings.Join(partStrs, ","), strings.Join(defs[i].LessThan, ","))
			}
		}

		expr, err := parseSimpleExprWithNames(p, ctx, buf.String(), schema, names)
		if err != nil {
			// If it got an error here, ddl may hang forever, so this error log is important.
			logutil.BgLogger().Error("wrong table partition expression", zap.String("expression", buf.String()), zap.Error(err))
			return nil, errors.Trace(err)
		}
		locateExprs = append(locateExprs, expr)
		buf.Reset()
	}
	return locateExprs, nil
}

func getColumnsOffset(cols, columns []*expression.Column) []int {
	colsOffset := make([]int, len(cols))
	for i, col := range columns {
		if idx := findIdxByColUniqueID(cols, col); idx >= 0 {
			colsOffset[idx] = i
		}
	}
	return colsOffset
}

func findIdxByColUniqueID(cols []*expression.Column, col *expression.Column) int {
	for idx, c := range cols {
		if c.UniqueID == col.UniqueID {
			return idx
		}
	}
	return -1
}

func extractPartitionExprColumns(ctx expression.BuildContext, expr string, partCols []model.CIStr, columns []*expression.Column, names types.NameSlice) (expression.Expression, []*expression.Column, []int, error) {
	var cols []*expression.Column
	var partExpr expression.Expression
	if len(partCols) == 0 {
		schema := expression.NewSchema(columns...)
		expr, err := expression.ParseSimpleExpr(ctx, expr, expression.WithInputSchemaAndNames(schema, names, nil))
		if err != nil {
			return nil, nil, nil, err
		}
		cols = expression.ExtractColumns(expr)
		partExpr = expr
	} else {
		for _, col := range partCols {
			idx := expression.FindFieldNameIdxByColName(names, col.L)
			if idx < 0 {
				panic("should never happen")
			}
			cols = append(cols, columns[idx])
		}
	}
	offset := getColumnsOffset(cols, columns)
	deDupCols := make([]*expression.Column, 0, len(cols))
	for _, col := range cols {
		if findIdxByColUniqueID(deDupCols, col) < 0 {
			c := col.Clone().(*expression.Column)
			deDupCols = append(deDupCols, c)
		}
	}
	return partExpr, deDupCols, offset, nil
}

func generateListPartitionExpr(ctx expression.BuildContext, tblInfo *model.TableInfo, expr string, partCols []model.CIStr,
	defs []model.PartitionDefinition, columns []*expression.Column, names types.NameSlice) (*PartitionExpr, error) {
	// The caller should assure partition info is not nil.
	partExpr, exprCols, offset, err := extractPartitionExprColumns(ctx, expr, partCols, columns, names)
	if err != nil {
		return nil, err
	}
	listPrune := &ForListPruning{}
	if len(partCols) == 0 {
		err = listPrune.buildListPruner(ctx, expr, defs, exprCols, columns, names)
	} else {
		err = listPrune.buildListColumnsPruner(ctx, tblInfo, partCols, defs, columns, names)
	}
	if err != nil {
		return nil, err
	}
	ret := &PartitionExpr{
		ForListPruning: listPrune,
		ColumnOffset:   offset,
		Expr:           partExpr,
	}
	return ret, nil
}

// Clone a copy of ForListPruning
func (lp *ForListPruning) Clone() *ForListPruning {
	ret := *lp
	if ret.LocateExpr != nil {
		ret.LocateExpr = lp.LocateExpr.Clone()
	}
	if ret.PruneExpr != nil {
		ret.PruneExpr = lp.PruneExpr.Clone()
	}
	ret.PruneExprCols = make([]*expression.Column, 0, len(lp.PruneExprCols))
	for i := range lp.PruneExprCols {
		c := lp.PruneExprCols[i].Clone().(*expression.Column)
		ret.PruneExprCols = append(ret.PruneExprCols, c)
	}
	ret.ColPrunes = make([]*ForListColumnPruning, 0, len(lp.ColPrunes))
	for i := range lp.ColPrunes {
		l := *lp.ColPrunes[i]
		l.ExprCol = l.ExprCol.Clone().(*expression.Column)
		ret.ColPrunes = append(ret.ColPrunes, &l)
	}
	return &ret
}

func (lp *ForListPruning) buildListPruner(ctx expression.BuildContext, exprStr string, defs []model.PartitionDefinition, exprCols []*expression.Column,
	columns []*expression.Column, names types.NameSlice) error {
	schema := expression.NewSchema(columns...)
	p := parser.New()
	expr, err := parseSimpleExprWithNames(p, ctx, exprStr, schema, names)
	if err != nil {
		// If it got an error here, ddl may hang forever, so this error log is important.
		logutil.BgLogger().Error("wrong table partition expression", zap.String("expression", exprStr), zap.Error(err))
		return errors.Trace(err)
	}
	// Since need to change the column index of the expression, clone the expression first.
	lp.LocateExpr = expr.Clone()
	lp.PruneExprCols = exprCols
	lp.PruneExpr = expr.Clone()
	cols := expression.ExtractColumns(lp.PruneExpr)
	for _, c := range cols {
		idx := findIdxByColUniqueID(exprCols, c)
		if idx < 0 {
			return table.ErrUnknownColumn.GenWithStackByArgs(c.OrigName)
		}
		c.Index = idx
	}
	err = lp.buildListPartitionValueMap(ctx, defs, schema, names, p)
	if err != nil {
		return err
	}
	return nil
}

func (lp *ForListPruning) buildListColumnsPruner(ctx expression.BuildContext,
	tblInfo *model.TableInfo, partCols []model.CIStr, defs []model.PartitionDefinition,
	columns []*expression.Column, names types.NameSlice) error {
	schema := expression.NewSchema(columns...)
	p := parser.New()
	colPrunes := make([]*ForListColumnPruning, 0, len(partCols))
	lp.defaultPartitionIdx = -1
	for colIdx := range partCols {
		colInfo := model.FindColumnInfo(tblInfo.Columns, partCols[colIdx].L)
		if colInfo == nil {
			return table.ErrUnknownColumn.GenWithStackByArgs(partCols[colIdx].L)
		}
		idx := expression.FindFieldNameIdxByColName(names, partCols[colIdx].L)
		if idx < 0 {
			return table.ErrUnknownColumn.GenWithStackByArgs(partCols[colIdx].L)
		}
		colPrune := &ForListColumnPruning{
			ctx:      ctx,
			tblInfo:  tblInfo,
			schema:   schema,
			names:    names,
			colIdx:   colIdx,
			ExprCol:  columns[idx],
			valueTp:  &colInfo.FieldType,
			valueMap: make(map[string]ListPartitionLocation),
			sorted:   btree.NewG[*btreeListColumnItem](btreeDegree, lessBtreeListColumnItem),
		}
		err := colPrune.buildPartitionValueMapAndSorted(p, defs)
		if err != nil {
			return err
		}
		if colPrune.defaultPartID > 0 {
			for i := range defs {
				if defs[i].ID == colPrune.defaultPartID {
					if lp.defaultPartitionIdx >= 0 && i != lp.defaultPartitionIdx {
						// Should be same for all columns, i.e. should never happen!
						return table.ErrUnknownPartition
					}
					lp.defaultPartitionIdx = i
				}
			}
		}
		colPrunes = append(colPrunes, colPrune)
	}
	lp.ColPrunes = colPrunes
	return nil
}

// buildListPartitionValueMap builds list partition value map.
// The map is column value -> partition index.
// colIdx is the column index in the list columns.
func (lp *ForListPruning) buildListPartitionValueMap(ctx expression.BuildContext, defs []model.PartitionDefinition,
	schema *expression.Schema, names types.NameSlice, p *parser.Parser) error {
	lp.valueMap = map[int64]int{}
	lp.nullPartitionIdx = -1
	lp.defaultPartitionIdx = -1
	for partitionIdx, def := range defs {
		for _, vs := range def.InValues {
			if strings.EqualFold(vs[0], "DEFAULT") {
				lp.defaultPartitionIdx = partitionIdx
				continue
			}
			expr, err := parseSimpleExprWithNames(p, ctx, vs[0], schema, names)
			if err != nil {
				return errors.Trace(err)
			}
			v, isNull, err := expr.EvalInt(ctx.GetEvalCtx(), chunk.Row{})
			if err != nil {
				return errors.Trace(err)
			}
			if isNull {
				lp.nullPartitionIdx = partitionIdx
				continue
			}
			lp.valueMap[v] = partitionIdx
		}
	}
	return nil
}

// LocatePartition locates partition by the column value
func (lp *ForListPruning) LocatePartition(value int64, isNull bool) int {
	if isNull {
		if lp.nullPartitionIdx >= 0 {
			return lp.nullPartitionIdx
		}
		return lp.defaultPartitionIdx
	}
	partitionIdx, ok := lp.valueMap[value]
	if !ok {
		return lp.defaultPartitionIdx
	}
	return partitionIdx
}

func (lp *ForListPruning) locateListPartitionByRow(ctx expression.EvalContext, r []types.Datum) (int, error) {
	value, isNull, err := lp.LocateExpr.EvalInt(ctx, chunk.MutRowFromDatums(r).ToRow())
	if err != nil {
		return -1, errors.Trace(err)
	}
	idx := lp.LocatePartition(value, isNull)
	if idx >= 0 {
		return idx, nil
	}
	if isNull {
		return -1, table.ErrNoPartitionForGivenValue.GenWithStackByArgs("NULL")
	}
	var valueMsg string
	if mysql.HasUnsignedFlag(lp.LocateExpr.GetType(ctx).GetFlag()) {
		// Handle unsigned value
		valueMsg = fmt.Sprintf("%d", uint64(value))
	} else {
		valueMsg = fmt.Sprintf("%d", value)
	}
	return -1, table.ErrNoPartitionForGivenValue.GenWithStackByArgs(valueMsg)
}

func (lp *ForListPruning) locateListColumnsPartitionByRow(tc types.Context, ec errctx.Context, r []types.Datum) (int, error) {
	helper := NewListPartitionLocationHelper()
	for _, colPrune := range lp.ColPrunes {
		location, err := colPrune.LocatePartition(tc, ec, r[colPrune.ExprCol.Index])
		if err != nil {
			return -1, errors.Trace(err)
		}
		if !helper.Intersect(location) {
			break
		}
	}
	location := helper.GetLocation()
	if location.IsEmpty() {
		if lp.defaultPartitionIdx >= 0 {
			return lp.defaultPartitionIdx, nil
		}
		return -1, table.ErrNoPartitionForGivenValue.GenWithStackByArgs("from column_list")
	}
	return location[0].PartIdx, nil
}

// GetDefaultIdx return the Default partitions index.
func (lp *ForListPruning) GetDefaultIdx() int {
	return lp.defaultPartitionIdx
}

// buildPartitionValueMapAndSorted builds list columns partition value map for the specified column.
// It also builds list columns partition value btree for the specified column.
// colIdx is the specified column index in the list columns.
func (lp *ForListColumnPruning) buildPartitionValueMapAndSorted(p *parser.Parser,
	defs []model.PartitionDefinition) error {
	l := len(lp.valueMap)
	if l != 0 {
		return nil
	}

	return lp.buildListPartitionValueMapAndSorted(p, defs)
}

// HasDefault return true if the partition has the DEFAULT value
func (lp *ForListColumnPruning) HasDefault() bool {
	return lp.defaultPartID > 0
}

// RebuildPartitionValueMapAndSorted rebuilds list columns partition value map for the specified column.
func (lp *ForListColumnPruning) RebuildPartitionValueMapAndSorted(p *parser.Parser,
	defs []model.PartitionDefinition) error {
	lp.valueMap = make(map[string]ListPartitionLocation, len(lp.valueMap))
	lp.sorted.Clear(false)
	return lp.buildListPartitionValueMapAndSorted(p, defs)
}

func (lp *ForListColumnPruning) buildListPartitionValueMapAndSorted(p *parser.Parser, defs []model.PartitionDefinition) error {
DEFS:
	for partitionIdx, def := range defs {
		for groupIdx, vs := range def.InValues {
			if len(vs) == 1 && vs[0] == "DEFAULT" {
				lp.defaultPartID = def.ID
				continue DEFS
			}
			keyBytes, err := lp.genConstExprKey(lp.ctx, vs[lp.colIdx], lp.schema, lp.names, p)
			if err != nil {
				return errors.Trace(err)
			}
			key := string(keyBytes)
			location, ok := lp.valueMap[key]
			if ok {
				idx := location.findByPartitionIdx(partitionIdx)
				if idx != -1 {
					location[idx].GroupIdxs = append(location[idx].GroupIdxs, groupIdx)
					continue
				}
			}
			location = append(location, ListPartitionGroup{
				PartIdx:   partitionIdx,
				GroupIdxs: []int{groupIdx},
			})
			lp.valueMap[key] = location
			lp.sorted.ReplaceOrInsert(newBtreeListColumnItem(key, location))
		}
	}
	return nil
}

func (lp *ForListColumnPruning) genConstExprKey(ctx expression.BuildContext, exprStr string,
	schema *expression.Schema, names types.NameSlice, p *parser.Parser) ([]byte, error) {
	expr, err := parseSimpleExprWithNames(p, ctx, exprStr, schema, names)
	if err != nil {
		return nil, errors.Trace(err)
	}
	v, err := expr.Eval(ctx.GetEvalCtx(), chunk.Row{})
	if err != nil {
		return nil, errors.Trace(err)
	}
	evalCtx := ctx.GetEvalCtx()
	tc, ec := evalCtx.TypeCtx(), evalCtx.ErrCtx()
	key, err := lp.genKey(tc, ec, v)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return key, nil
}

func (lp *ForListColumnPruning) genKey(tc types.Context, ec errctx.Context, v types.Datum) ([]byte, error) {
	v, err := v.ConvertTo(tc, lp.valueTp)
	if err != nil {
		return nil, errors.Trace(err)
	}
	valByte, err := codec.EncodeKey(tc.Location(), nil, v)
	err = ec.HandleError(err)
	return valByte, err
}

// LocatePartition locates partition by the column value
func (lp *ForListColumnPruning) LocatePartition(tc types.Context, ec errctx.Context, v types.Datum) (ListPartitionLocation, error) {
	key, err := lp.genKey(tc, ec, v)
	if err != nil {
		return nil, errors.Trace(err)
	}
	location, ok := lp.valueMap[string(key)]
	if !ok {
		return nil, nil
	}
	return location, nil
}

// LocateRanges locates partition ranges by the column range
func (lp *ForListColumnPruning) LocateRanges(tc types.Context, ec errctx.Context, r *ranger.Range, defaultPartIdx int) ([]ListPartitionLocation, error) {
	var lowKey, highKey []byte
	var err error
	lowVal := r.LowVal[0]
	if r.LowVal[0].Kind() == types.KindMinNotNull {
		lowVal = types.GetMinValue(lp.ExprCol.GetType(lp.ctx.GetEvalCtx()))
	}
	highVal := r.HighVal[0]
	if r.HighVal[0].Kind() == types.KindMaxValue {
		highVal = types.GetMaxValue(lp.ExprCol.GetType(lp.ctx.GetEvalCtx()))
	}

	// For string type, values returned by GetMinValue and GetMaxValue are already encoded,
	// so it's unnecessary to invoke genKey to encode them.
	if lp.ExprCol.GetType(lp.ctx.GetEvalCtx()).EvalType() == types.ETString && r.LowVal[0].Kind() == types.KindMinNotNull {
		lowKey = (&lowVal).GetBytes()
	} else {
		lowKey, err = lp.genKey(tc, ec, lowVal)
		if err != nil {
			return nil, errors.Trace(err)
		}
	}

	if lp.ExprCol.GetType(lp.ctx.GetEvalCtx()).EvalType() == types.ETString && r.HighVal[0].Kind() == types.KindMaxValue {
		highKey = (&highVal).GetBytes()
	} else {
		highKey, err = lp.genKey(tc, ec, highVal)
		if err != nil {
			return nil, errors.Trace(err)
		}
	}

	if r.LowExclude {
		lowKey = kv.Key(lowKey).PrefixNext()
	}
	if !r.HighExclude {
		highKey = kv.Key(highKey).PrefixNext()
	}

	locations := make([]ListPartitionLocation, 0, lp.sorted.Len())
	lp.sorted.AscendRange(newBtreeListColumnSearchItem(string(hack.String(lowKey))), newBtreeListColumnSearchItem(string(hack.String(highKey))), func(item *btreeListColumnItem) bool {
		locations = append(locations, item.location)
		return true
	})
	if lp.HasDefault() {
		// Add the default partition since there may be a gap
		// between the conditions range and the LIST COLUMNS values
		locations = append(locations, ListPartitionLocation{
			ListPartitionGroup{
				PartIdx:   defaultPartIdx,
				GroupIdxs: []int{-1}, // Special group!
			},
		})
	}
	return locations, nil
}

func generateHashPartitionExpr(ctx expression.BuildContext, exprStr string,
	columns []*expression.Column, names types.NameSlice) (*PartitionExpr, error) {
	// The caller should assure partition info is not nil.
	schema := expression.NewSchema(columns...)
	origExpr, err := parseExpr(parser.New(), exprStr)
	if err != nil {
		return nil, err
	}
	exprs, err := expression.BuildSimpleExpr(ctx, origExpr, expression.WithInputSchemaAndNames(schema, names, nil))
	if err != nil {
		// If it got an error here, ddl may hang forever, so this error log is important.
		logutil.BgLogger().Error("wrong table partition expression", zap.String("expression", exprStr), zap.Error(err))
		return nil, errors.Trace(err)
	}
	// build column offset.
	partitionCols := expression.ExtractColumns(exprs)
	offset := make([]int, len(partitionCols))
	for i, col := range columns {
		for j, partitionCol := range partitionCols {
			if partitionCol.UniqueID == col.UniqueID {
				offset[j] = i
			}
		}
	}
	exprs.HashCode()
	return &PartitionExpr{
		Expr:         exprs,
		OrigExpr:     origExpr,
		ColumnOffset: offset,
	}, nil
}

// PartitionExpr returns the partition expression.
func (t *partitionedTable) PartitionExpr() *PartitionExpr {
	return t.partitionExpr
}

func (t *partitionedTable) GetPartitionColumnIDs() []int64 {
	// PARTITION BY {LIST|RANGE} COLUMNS uses columns directly without expressions
	pi := t.Meta().Partition
	if len(pi.Columns) > 0 {
		colIDs := make([]int64, 0, len(pi.Columns))
		for _, name := range pi.Columns {
			col := table.FindColLowerCase(t.Cols(), name.L)
			if col == nil {
				// For safety, should not happen
				continue
			}
			colIDs = append(colIDs, col.ID)
		}
		return colIDs
	}
	if t.partitionExpr == nil {
		return nil
	}

	partitionCols := expression.ExtractColumns(t.partitionExpr.Expr)
	colIDs := make([]int64, 0, len(partitionCols))
	for _, col := range partitionCols {
		colIDs = append(colIDs, col.ID)
	}
	return colIDs
}

func (t *partitionedTable) GetPartitionColumnNames() []model.CIStr {
	pi := t.Meta().Partition
	if len(pi.Columns) > 0 {
		return pi.Columns
	}
	colIDs := t.GetPartitionColumnIDs()
	colNames := make([]model.CIStr, 0, len(colIDs))
	for _, colID := range colIDs {
		for _, col := range t.Cols() {
			if col.ID == colID {
				colNames = append(colNames, col.Name)
			}
		}
	}
	return colNames
}

// PartitionRecordKey is exported for test.
func PartitionRecordKey(pid int64, handle int64) kv.Key {
	recordPrefix := tablecodec.GenTableRecordPrefix(pid)
	return tablecodec.EncodeRecordKey(recordPrefix, kv.IntHandle(handle))
}

func (t *partitionedTable) CheckForExchangePartition(ctx expression.EvalContext, pi *model.PartitionInfo, r []types.Datum, partID, ntID int64) error {
	defID, err := t.locatePartition(ctx, r)
	if err != nil {
		return err
	}
	if defID != partID && defID != ntID {
		return errors.WithStack(table.ErrRowDoesNotMatchGivenPartitionSet)
	}
	return nil
}

// locatePartitionCommon returns the partition idx of the input record.
func (t *partitionedTable) locatePartitionCommon(ctx expression.EvalContext, tp model.PartitionType, partitionExpr *PartitionExpr, num uint64, columnsPartitioned bool, r []types.Datum) (int, error) {
	var err error
	var idx int
	switch tp {
	case model.PartitionTypeRange:
		if columnsPartitioned {
			idx, err = t.locateRangeColumnPartition(ctx, partitionExpr, r)
		} else {
			idx, err = t.locateRangePartition(ctx, partitionExpr, r)
		}
	case model.PartitionTypeHash:
		// Note that only LIST and RANGE supports REORGANIZE PARTITION
		idx, err = t.locateHashPartition(ctx, partitionExpr, num, r)
	case model.PartitionTypeKey:
		idx, err = partitionExpr.LocateKeyPartition(num, r)
	case model.PartitionTypeList:
		idx, err = partitionExpr.locateListPartition(ctx, r)
	case model.PartitionTypeNone:
		idx = 0
	}
	if err != nil {
		return 0, errors.Trace(err)
	}
	return idx, nil
}

func (t *partitionedTable) locatePartitionIdx(ctx expression.EvalContext, r []types.Datum) (int, error) {
	pi := t.Meta().GetPartitionInfo()
	columnsSet := len(t.meta.Partition.Columns) > 0
	idx, err := t.locatePartitionCommon(ctx, pi.Type, t.partitionExpr, pi.Num, columnsSet, r)
	if err != nil {
		return -1, errors.Trace(err)
	}
	return idx, nil
}

func (t *partitionedTable) locatePartition(ctx expression.EvalContext, r []types.Datum) (int64, error) {
	idx, err := t.locatePartitionIdx(ctx, r)
	if err != nil {
		return 0, errors.Trace(err)
	}
	pi := t.Meta().GetPartitionInfo()
	return pi.Definitions[idx].ID, nil
}

func (t *partitionedTable) locateReorgPartition(ctx expression.EvalContext, r []types.Datum) (int64, error) {
	pi := t.Meta().GetPartitionInfo()
	columnsSet := len(pi.DDLColumns) > 0
	// Note that for KEY/HASH partitioning, since we do not support LINEAR,
	// all partitions will be reorganized,
	// so we can use the number in Dropping or AddingDefinitions,
	// depending on current state.
	num := len(pi.AddingDefinitions)
	if pi.DDLState == model.StateDeleteReorganization {
		num = len(pi.DroppingDefinitions)
	}
	idx, err := t.locatePartitionCommon(ctx, pi.DDLType, t.reorgPartitionExpr, uint64(num), columnsSet, r)
	if err != nil {
		return 0, errors.Trace(err)
	}
	if pi.DDLState == model.StateDeleteReorganization {
		return pi.DroppingDefinitions[idx].ID, nil
	}
	return pi.AddingDefinitions[idx].ID, nil
}

func (t *partitionedTable) locateRangeColumnPartition(ctx expression.EvalContext, partitionExpr *PartitionExpr, r []types.Datum) (int, error) {
	upperBounds := partitionExpr.UpperBounds
	var lastError error
	evalBuffer := t.evalBufferPool.Get().(*chunk.MutRow)
	defer t.evalBufferPool.Put(evalBuffer)
	idx := sort.Search(len(upperBounds), func(i int) bool {
		evalBuffer.SetDatums(r...)
		ret, isNull, err := upperBounds[i].EvalInt(ctx, evalBuffer.ToRow())
		if err != nil {
			lastError = err
			return true // Does not matter, will propagate the last error anyway.
		}
		if isNull {
			// If the column value used to determine the partition is NULL, the row is inserted into the lowest partition.
			// See https://dev.mysql.com/doc/mysql-partitioning-excerpt/5.7/en/partitioning-handling-nulls.html
			return true // Always less than any other value (NULL cannot be in the partition definition VALUE LESS THAN).
		}
		return ret > 0
	})
	if lastError != nil {
		return 0, errors.Trace(lastError)
	}
	if idx >= len(upperBounds) {
		return 0, table.ErrNoPartitionForGivenValue.GenWithStackByArgs("from column_list")
	}
	return idx, nil
}

func (pe *PartitionExpr) locateListPartition(ctx expression.EvalContext, r []types.Datum) (int, error) {
	lp := pe.ForListPruning
	if len(lp.ColPrunes) == 0 {
		return lp.locateListPartitionByRow(ctx, r)
	}
	tc, ec := ctx.TypeCtx(), ctx.ErrCtx()
	return lp.locateListColumnsPartitionByRow(tc, ec, r)
}

func (t *partitionedTable) locateRangePartition(ctx expression.EvalContext, partitionExpr *PartitionExpr, r []types.Datum) (int, error) {
	var (
		ret    int64
		val    int64
		isNull bool
		err    error
	)
	if col, ok := partitionExpr.Expr.(*expression.Column); ok {
		if r[col.Index].IsNull() {
			isNull = true
		}
		ret = r[col.Index].GetInt64()
	} else {
		evalBuffer := t.evalBufferPool.Get().(*chunk.MutRow)
		defer t.evalBufferPool.Put(evalBuffer)
		evalBuffer.SetDatums(r...)
		val, isNull, err = partitionExpr.Expr.EvalInt(ctx, evalBuffer.ToRow())
		if err != nil {
			return 0, err
		}
		ret = val
	}
	unsigned := mysql.HasUnsignedFlag(partitionExpr.Expr.GetType(ctx).GetFlag())
	ranges := partitionExpr.ForRangePruning
	length := len(ranges.LessThan)
	pos := sort.Search(length, func(i int) bool {
		if isNull {
			return true
		}
		return ranges.Compare(i, ret, unsigned) > 0
	})
	if isNull {
		pos = 0
	}
	if pos < 0 || pos >= length {
		// The data does not belong to any of the partition returns `table has no partition for value %s`.
		var valueMsg string
		if unsigned {
			valueMsg = fmt.Sprintf("%d", uint64(ret))
		} else {
			valueMsg = fmt.Sprintf("%d", ret)
		}
		return 0, table.ErrNoPartitionForGivenValue.GenWithStackByArgs(valueMsg)
	}
	return pos, nil
}

// TODO: supports linear hashing
func (t *partitionedTable) locateHashPartition(ctx expression.EvalContext, partExpr *PartitionExpr, numParts uint64, r []types.Datum) (int, error) {
	if col, ok := partExpr.Expr.(*expression.Column); ok {
		var data types.Datum
		switch r[col.Index].Kind() {
		case types.KindInt64, types.KindUint64:
			data = r[col.Index]
		default:
			var err error
			data, err = r[col.Index].ConvertTo(ctx.TypeCtx(), types.NewFieldType(mysql.TypeLong))
			if err != nil {
				return 0, err
			}
		}
		ret := data.GetInt64()
		ret = ret % int64(numParts)
		if ret < 0 {
			ret = -ret
		}
		return int(ret), nil
	}
	evalBuffer := t.evalBufferPool.Get().(*chunk.MutRow)
	defer t.evalBufferPool.Put(evalBuffer)
	evalBuffer.SetDatums(r...)
	ret, isNull, err := partExpr.Expr.EvalInt(ctx, evalBuffer.ToRow())
	if err != nil {
		return 0, err
	}
	if isNull {
		return 0, nil
	}
	ret = ret % int64(numParts)
	if ret < 0 {
		ret = -ret
	}
	return int(ret), nil
}

// GetPartition returns a Table, which is actually a partition.
func (t *partitionedTable) GetPartition(pid int64) table.PhysicalTable {
	// Attention, can't simply use `return t.partitions[pid]` here.
	// Because A nil of type *partition is a kind of `table.PhysicalTable`
	part, ok := t.partitions[pid]
	if !ok {
		// Should never happen!
		return nil
	}
	return part
}

// GetReorganizedPartitionedTable returns the same table
// but only with the AddingDefinitions used.
func GetReorganizedPartitionedTable(t table.Table) (table.PartitionedTable, error) {
	// This is used during Reorganize partitions; All data from DroppingDefinitions
	// will be copied to AddingDefinitions, so only setup with AddingDefinitions!

	// Do not change any Definitions of t, but create a new struct.
	if t.GetPartitionedTable() == nil {
		return nil, dbterror.ErrUnsupportedReorganizePartition.GenWithStackByArgs()
	}
	tblInfo := t.Meta().Clone()
	pi := tblInfo.Partition
	pi.Definitions = pi.AddingDefinitions
	pi.Num = uint64(len(pi.Definitions))
	pi.AddingDefinitions = nil
	pi.DroppingDefinitions = nil

	// Reorganized status, use the new values
	pi.Type = pi.DDLType
	pi.Expr = pi.DDLExpr
	pi.Columns = pi.DDLColumns
	tblInfo.ID = pi.NewTableID

	constraints, err := table.LoadCheckConstraint(tblInfo)
	if err != nil {
		return nil, err
	}
	var tc TableCommon
	initTableCommon(&tc, tblInfo, tblInfo.ID, t.Cols(), t.Allocators(nil), constraints)

	// and rebuild the partitioning structure
	return newPartitionedTable(&tc, tblInfo)
}

// GetPartitionByRow returns a Table, which is actually a Partition.
func (t *partitionedTable) GetPartitionByRow(ctx expression.EvalContext, r []types.Datum) (table.PhysicalTable, error) {
	pid, err := t.locatePartition(ctx, r)
	if err != nil {
		return nil, errors.Trace(err)
	}
	return t.partitions[pid], nil
}

// GetPartitionIdxByRow returns the index in PartitionDef for the matching partition
func (t *partitionedTable) GetPartitionIdxByRow(ctx expression.EvalContext, r []types.Datum) (int, error) {
	return t.locatePartitionIdx(ctx, r)
}

// GetPartitionByRow returns a Table, which is actually a Partition.
func (t *partitionTableWithGivenSets) GetPartitionByRow(ctx expression.EvalContext, r []types.Datum) (table.PhysicalTable, error) {
	pid, err := t.locatePartition(ctx, r)
	if err != nil {
		return nil, errors.Trace(err)
	}
	if _, ok := t.givenSetPartitions[pid]; !ok {
		return nil, errors.WithStack(table.ErrRowDoesNotMatchGivenPartitionSet)
	}
	return t.partitions[pid], nil
}

// checkConstraintForExchangePartition is only used for ExchangePartition by partitionTable during write only state.
// It check if rowData inserted or updated violate checkConstraints of non-partitionTable.
func checkConstraintForExchangePartition(sctx table.MutateContext, row []types.Datum, partID, ntID int64) error {
	type InfoSchema interface {
		TableByID(id int64) (val table.Table, ok bool)
	}
	is, ok := sctx.GetDomainInfoSchema().(InfoSchema)
	if !ok {
		return errors.Errorf("exchange partition process assert inforSchema failed")
	}
	nt, tableFound := is.TableByID(ntID)
	if !tableFound {
		// Now partID is nt tableID.
		nt, tableFound = is.TableByID(partID)
		if !tableFound {
			return errors.Errorf("exchange partition process table by id failed")
		}
	}
	type CheckConstraintTable interface {
		CheckRowConstraint(ctx table.MutateContext, rowToCheck []types.Datum) error
	}
	cc, ok := nt.(CheckConstraintTable)
	if !ok {
		return errors.Errorf("exchange partition process assert check constraint failed")
	}
	err := cc.CheckRowConstraint(sctx, row)
	if err != nil {
		// TODO: make error include ExchangePartition info.
		return err
	}
	return nil
}

// AddRecord implements the AddRecord method for the table.Table interface.
func (t *partitionedTable) AddRecord(ctx table.MutateContext, r []types.Datum, opts ...table.AddRecordOption) (recordID kv.Handle, err error) {
	return partitionedTableAddRecord(ctx, t, r, nil, opts)
}

func partitionedTableAddRecord(ctx table.MutateContext, t *partitionedTable, r []types.Datum, partitionSelection map[int64]struct{}, opts []table.AddRecordOption) (recordID kv.Handle, err error) {
	pid, err := t.locatePartition(ctx.GetExprCtx().GetEvalCtx(), r)
	if err != nil {
		return nil, errors.Trace(err)
	}

	if partitionSelection != nil {
		if _, ok := partitionSelection[pid]; !ok {
			return nil, errors.WithStack(table.ErrRowDoesNotMatchGivenPartitionSet)
		}
	}
	if t.Meta().Partition.HasTruncatingPartitionID(pid) {
		return nil, errors.WithStack(dbterror.ErrInvalidDDLState.GenWithStack("the partition is in not in public"))
	}
	exchangePartitionInfo := t.Meta().ExchangePartitionInfo
	if exchangePartitionInfo != nil && exchangePartitionInfo.ExchangePartitionDefID == pid &&
		variable.EnableCheckConstraint.Load() {
		err = checkConstraintForExchangePartition(ctx, r, pid, exchangePartitionInfo.ExchangePartitionTableID)
		if err != nil {
			return nil, errors.WithStack(err)
		}
	}
	tbl := t.GetPartition(pid)
	recordID, err = tbl.AddRecord(ctx, r, opts...)
	if err != nil {
		return
	}
	if t.Meta().Partition.DDLState == model.StateDeleteOnly {
		return
	}
	if _, ok := t.reorganizePartitions[pid]; ok {
		// Double write to the ongoing reorganized partition
		pid, err = t.locateReorgPartition(ctx.GetExprCtx().GetEvalCtx(), r)
		if err != nil {
			return nil, errors.Trace(err)
		}
		tbl = t.GetPartition(pid)
		recordID, err = tbl.AddRecord(ctx, r, opts...)
		if err != nil {
			return
		}
	}
	return
}

// partitionTableWithGivenSets is used for this kind of grammar: partition (p0,p1)
// Basically it is the same as partitionedTable except that partitionTableWithGivenSets
// checks the given partition set for AddRecord/UpdateRecord operations.
type partitionTableWithGivenSets struct {
	*partitionedTable
	givenSetPartitions map[int64]struct{}
}

// NewPartitionTableWithGivenSets creates a new partition table from a partition table.
func NewPartitionTableWithGivenSets(tbl table.PartitionedTable, partitions map[int64]struct{}) table.PartitionedTable {
	if raw, ok := tbl.(*partitionedTable); ok {
		return &partitionTableWithGivenSets{
			partitionedTable:   raw,
			givenSetPartitions: partitions,
		}
	}
	return tbl
}

// AddRecord implements the AddRecord method for the table.Table interface.
func (t *partitionTableWithGivenSets) AddRecord(ctx table.MutateContext, r []types.Datum, opts ...table.AddRecordOption) (recordID kv.Handle, err error) {
	return partitionedTableAddRecord(ctx, t.partitionedTable, r, t.givenSetPartitions, opts)
}

func (t *partitionTableWithGivenSets) GetAllPartitionIDs() []int64 {
	ptIDs := make([]int64, 0, len(t.partitions))
	for id := range t.givenSetPartitions {
		ptIDs = append(ptIDs, id)
	}
	return ptIDs
}

// RemoveRecord implements table.Table RemoveRecord interface.
func (t *partitionedTable) RemoveRecord(ctx table.MutateContext, h kv.Handle, r []types.Datum) error {
	ectx := ctx.GetExprCtx()
	pid, err := t.locatePartition(ectx.GetEvalCtx(), r)
	if err != nil {
		return errors.Trace(err)
	}

	tbl := t.GetPartition(pid)
	err = tbl.RemoveRecord(ctx, h, r)
	if err != nil {
		return errors.Trace(err)
	}

	if _, ok := t.reorganizePartitions[pid]; ok {
		pid, err = t.locateReorgPartition(ectx.GetEvalCtx(), r)
		if err != nil {
			return errors.Trace(err)
		}
		tbl = t.GetPartition(pid)
		err = tbl.RemoveRecord(ctx, h, r)
		if err != nil {
			return errors.Trace(err)
		}
	}
	return nil
}

func (t *partitionedTable) GetAllPartitionIDs() []int64 {
	ptIDs := make([]int64, 0, len(t.partitions))
	for id := range t.partitions {
		if _, ok := t.doubleWritePartitions[id]; ok {
			continue
		}
		ptIDs = append(ptIDs, id)
	}
	return ptIDs
}

// UpdateRecord implements table.Table UpdateRecord interface.
// `touched` means which columns are really modified, used for secondary indices.
// Length of `oldData` and `newData` equals to length of `t.WritableCols()`.
func (t *partitionedTable) UpdateRecord(ctx context.Context, sctx table.MutateContext, h kv.Handle, currData, newData []types.Datum, touched []bool) error {
	return partitionedTableUpdateRecord(ctx, sctx, t, h, currData, newData, touched, nil)
}

func (t *partitionTableWithGivenSets) UpdateRecord(ctx context.Context, sctx table.MutateContext, h kv.Handle, currData, newData []types.Datum, touched []bool) error {
	return partitionedTableUpdateRecord(ctx, sctx, t.partitionedTable, h, currData, newData, touched, t.givenSetPartitions)
}

func partitionedTableUpdateRecord(gctx context.Context, ctx table.MutateContext, t *partitionedTable, h kv.Handle, currData, newData []types.Datum, touched []bool, partitionSelection map[int64]struct{}) error {
	ectx := ctx.GetExprCtx()
	from, err := t.locatePartition(ectx.GetEvalCtx(), currData)
	if err != nil {
		return errors.Trace(err)
	}
	to, err := t.locatePartition(ectx.GetEvalCtx(), newData)
	if err != nil {
		return errors.Trace(err)
	}
	if partitionSelection != nil {
		if _, ok := partitionSelection[to]; !ok {
			return errors.WithStack(table.ErrRowDoesNotMatchGivenPartitionSet)
		}
		// Should not have been read from this partition! Checked already in GetPartitionByRow()
		if _, ok := partitionSelection[from]; !ok {
			return errors.WithStack(table.ErrRowDoesNotMatchGivenPartitionSet)
		}
	}
	if t.Meta().Partition.HasTruncatingPartitionID(to) {
		return errors.WithStack(dbterror.ErrInvalidDDLState.GenWithStack("the partition is in not in public"))
	}
	exchangePartitionInfo := t.Meta().ExchangePartitionInfo
	if exchangePartitionInfo != nil && exchangePartitionInfo.ExchangePartitionDefID == to &&
		variable.EnableCheckConstraint.Load() {
		err = checkConstraintForExchangePartition(ctx, newData, to, exchangePartitionInfo.ExchangePartitionTableID)
		if err != nil {
			return errors.WithStack(err)
		}
	}

	txn, err := ctx.Txn(true)
	if err != nil {
		return errors.Trace(err)
	}
	memBuffer := txn.GetMemBuffer()
	sh := memBuffer.Staging()
	defer memBuffer.Cleanup(sh)

	// The old and new data locate in different partitions.
	// Remove record from old partition and add record to new partition.
	if from != to {
		err = t.GetPartition(from).RemoveRecord(ctx, h, currData)
		if err != nil {
			return errors.Trace(err)
		}

		_, err = t.GetPartition(to).AddRecord(ctx, newData)
		if err != nil {
			return errors.Trace(err)
		}

		newTo, newFrom := int64(0), int64(0)
		if _, ok := t.reorganizePartitions[to]; ok {
			newTo, err = t.locateReorgPartition(ectx.GetEvalCtx(), newData)
			// There might be valid cases when errors should be accepted?
			if err != nil {
				return errors.Trace(err)
			}
		}
		if _, ok := t.reorganizePartitions[from]; ok {
			newFrom, err = t.locateReorgPartition(ectx.GetEvalCtx(), currData)
			// There might be valid cases when errors should be accepted?
			if err != nil {
				return errors.Trace(err)
			}
		}
		if newTo == newFrom && newTo != 0 {
			// Update needs to be done in StateDeleteOnly as well
			err = t.GetPartition(newTo).UpdateRecord(gctx, ctx, h, currData, newData, touched)
			if err != nil {
				return errors.Trace(err)
			}
			memBuffer.Release(sh)
			return nil
		}

		if newFrom != 0 {
			err = t.GetPartition(newFrom).RemoveRecord(ctx, h, currData)
			// TODO: Can this happen? When the data is not yet backfilled?
			if err != nil {
				return errors.Trace(err)
			}
		}
		if newTo != 0 && t.Meta().GetPartitionInfo().DDLState != model.StateDeleteOnly {
			_, err = t.GetPartition(newTo).AddRecord(ctx, newData)
			if err != nil {
				return errors.Trace(err)
			}
		}
		memBuffer.Release(sh)
		return nil
	}
	tbl := t.GetPartition(to)
	err = tbl.UpdateRecord(gctx, ctx, h, currData, newData, touched)
	if err != nil {
		return errors.Trace(err)
	}
	if _, ok := t.reorganizePartitions[to]; ok {
		// Even if to == from, in the reorganized partitions they may differ
		// like in case of a split
		newTo, err := t.locateReorgPartition(ectx.GetEvalCtx(), newData)
		if err != nil {
			return errors.Trace(err)
		}
		newFrom, err := t.locateReorgPartition(ectx.GetEvalCtx(), currData)
		if err != nil {
			return errors.Trace(err)
		}
		if newTo == newFrom {
			tbl = t.GetPartition(newTo)
			if t.Meta().Partition.DDLState == model.StateDeleteOnly {
				err = tbl.RemoveRecord(ctx, h, currData)
			} else {
				err = tbl.UpdateRecord(gctx, ctx, h, currData, newData, touched)
			}
			if err != nil {
				return errors.Trace(err)
			}
			memBuffer.Release(sh)
			return nil
		}
		tbl = t.GetPartition(newFrom)
		err = tbl.RemoveRecord(ctx, h, currData)
		if err != nil {
			return errors.Trace(err)
		}
		if t.Meta().GetPartitionInfo().DDLState != model.StateDeleteOnly {
			tbl = t.GetPartition(newTo)
			_, err = tbl.AddRecord(ctx, newData)
			if err != nil {
				return errors.Trace(err)
			}
		}
	}
	memBuffer.Release(sh)
	return nil
}

// FindPartitionByName finds partition in table meta by name.
func FindPartitionByName(meta *model.TableInfo, parName string) (int64, error) {
	// Hash partition table use p0, p1, p2, p3 as partition names automatically.
	parName = strings.ToLower(parName)
	for _, def := range meta.Partition.Definitions {
		if strings.EqualFold(def.Name.L, parName) {
			return def.ID, nil
		}
	}
	return -1, errors.Trace(table.ErrUnknownPartition.GenWithStackByArgs(parName, meta.Name.O))
}

func parseExpr(p *parser.Parser, exprStr string) (ast.ExprNode, error) {
	exprStr = "select " + exprStr
	stmts, _, err := p.ParseSQL(exprStr)
	if err != nil {
		// if you want to use warn like an error, trace the stack info by yourself.
		return nil, errors.Trace(util.SyntaxWarn(err))
	}
	fields := stmts[0].(*ast.SelectStmt).Fields.Fields
	return fields[0].Expr, nil
}

func compareUnsigned(v1, v2 int64) int {
	switch {
	case uint64(v1) > uint64(v2):
		return 1
	case uint64(v1) == uint64(v2):
		return 0
	}
	return -1
}

// Compare is to be used in the binary search to locate partition
func (lt *ForRangePruning) Compare(ith int, v int64, unsigned bool) int {
	if ith == len(lt.LessThan)-1 {
		if lt.MaxValue {
			return 1
		}
	}
	if unsigned {
		return compareUnsigned(lt.LessThan[ith], v)
	}
	switch {
	case lt.LessThan[ith] > v:
		return 1
	case lt.LessThan[ith] == v:
		return 0
	}
	return -1
}