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180 lines
4.7 KiB
180 lines
4.7 KiB
// Copyright 2017 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 ranger
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import (
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"fmt"
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"math"
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"strings"
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"github.com/pingcap/errors"
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"github.com/pingcap/tidb/kv"
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"github.com/pingcap/tidb/sessionctx/stmtctx"
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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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// Range represents a range generated in physical plan building phase.
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type Range struct {
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LowVal []types.Datum
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HighVal []types.Datum
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LowExclude bool // Low value is exclusive.
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HighExclude bool // High value is exclusive.
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}
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// Clone clones a Range.
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func (ran *Range) Clone() *Range {
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newRange := &Range{
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LowVal: make([]types.Datum, 0, len(ran.LowVal)),
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HighVal: make([]types.Datum, 0, len(ran.HighVal)),
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LowExclude: ran.LowExclude,
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HighExclude: ran.HighExclude,
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}
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for i, length := 0, len(ran.LowVal); i < length; i++ {
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newRange.LowVal = append(newRange.LowVal, ran.LowVal[i])
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}
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for i, length := 0, len(ran.HighVal); i < length; i++ {
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newRange.HighVal = append(newRange.HighVal, ran.HighVal[i])
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}
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return newRange
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}
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// IsPoint returns if the range is a point.
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func (ran *Range) IsPoint(sc *stmtctx.StatementContext) bool {
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if len(ran.LowVal) != len(ran.HighVal) {
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return false
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}
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for i := range ran.LowVal {
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a := ran.LowVal[i]
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b := ran.HighVal[i]
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if a.Kind() == types.KindMinNotNull || b.Kind() == types.KindMaxValue {
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return false
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}
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cmp, err := a.CompareDatum(sc, &b)
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if err != nil {
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return false
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}
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if cmp != 0 {
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return false
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}
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if a.IsNull() {
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return false
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}
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}
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return !ran.LowExclude && !ran.HighExclude
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}
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// IsFullRange check if the range is full scan range
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func (ran *Range) IsFullRange() bool {
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if len(ran.LowVal) != len(ran.HighVal) {
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return false
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}
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for i := range ran.LowVal {
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lowValRawString := formatDatum(ran.LowVal[i], true)
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highValRawString := formatDatum(ran.HighVal[i], false)
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if ("-inf" != lowValRawString && "NULL" != lowValRawString) ||
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("+inf" != highValRawString && "NULL" != highValRawString) {
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return false
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}
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}
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return true
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}
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// String implements the Stringer interface.
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func (ran *Range) String() string {
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lowStrs := make([]string, 0, len(ran.LowVal))
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for _, d := range ran.LowVal {
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lowStrs = append(lowStrs, formatDatum(d, true))
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}
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highStrs := make([]string, 0, len(ran.LowVal))
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for _, d := range ran.HighVal {
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highStrs = append(highStrs, formatDatum(d, false))
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}
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l, r := "[", "]"
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if ran.LowExclude {
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l = "("
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}
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if ran.HighExclude {
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r = ")"
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}
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return l + strings.Join(lowStrs, " ") + "," + strings.Join(highStrs, " ") + r
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}
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// Encode encodes the range to its encoded value.
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func (ran *Range) Encode(sc *stmtctx.StatementContext, lowBuffer, highBuffer []byte) ([]byte, []byte, error) {
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var err error
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lowBuffer, err = codec.EncodeKey(sc, lowBuffer[:0], ran.LowVal...)
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if err != nil {
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return nil, nil, err
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}
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if ran.LowExclude {
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lowBuffer = kv.Key(lowBuffer).PrefixNext()
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}
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highBuffer, err = codec.EncodeKey(sc, highBuffer[:0], ran.HighVal...)
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if err != nil {
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return nil, nil, err
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}
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if !ran.HighExclude {
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highBuffer = kv.Key(highBuffer).PrefixNext()
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}
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return lowBuffer, highBuffer, nil
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}
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// PrefixEqualLen tells you how long the prefix of the range is a point.
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// e.g. If this range is (1 2 3, 1 2 +inf), then the return value is 2.
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func (ran *Range) PrefixEqualLen(sc *stmtctx.StatementContext) (int, error) {
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// Here, len(ran.LowVal) always equal to len(ran.HighVal)
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for i := 0; i < len(ran.LowVal); i++ {
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cmp, err := ran.LowVal[i].CompareDatum(sc, &ran.HighVal[i])
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if err != nil {
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return 0, errors.Trace(err)
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}
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if cmp != 0 {
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return i, nil
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}
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}
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return len(ran.LowVal), nil
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}
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func formatDatum(d types.Datum, isLeftSide bool) string {
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switch d.Kind() {
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case types.KindNull:
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return "NULL"
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case types.KindMinNotNull:
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return "-inf"
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case types.KindMaxValue:
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return "+inf"
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case types.KindInt64:
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switch d.GetInt64() {
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case math.MinInt64:
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if isLeftSide {
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return "-inf"
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}
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case math.MaxInt64:
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if !isLeftSide {
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return "+inf"
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}
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}
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case types.KindUint64:
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if d.GetUint64() == math.MaxUint64 && !isLeftSide {
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return "+inf"
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}
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case types.KindString, types.KindBytes, types.KindMysqlEnum, types.KindMysqlSet,
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types.KindMysqlJSON, types.KindBinaryLiteral, types.KindMysqlBit:
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return fmt.Sprintf("\"%v\"", d.GetValue())
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}
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return fmt.Sprintf("%v", d.GetValue())
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}
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