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index.go
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index.go
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// Copyright 2020-2021 Dolthub, 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 memory
import (
"fmt"
"strings"
"time"
"github.com/Rock-liyi/p2pdb-store/sql"
"github.com/Rock-liyi/p2pdb-store/sql/expression"
)
const CommentPreventingIndexBuilding = "__FOR TESTING: I cannot be built__"
type Index struct {
DB string // required for engine tests with driver
DriverName string // required for engine tests with driver
Tbl *Table // required for engine tests with driver
TableName string
Exprs []sql.Expression
Name string
Unique bool
CommentStr string
}
var _ sql.Index = (*Index)(nil)
func (idx *Index) Database() string { return idx.DB }
func (idx *Index) Driver() string { return idx.DriverName }
func (idx *Index) MemTable() *Table { return idx.Tbl }
func (idx *Index) ColumnExpressions() []sql.Expression { return idx.Exprs }
func (idx *Index) IsGenerated() bool { return false }
func (idx *Index) Expressions() []string {
var exprs []string
for _, e := range idx.Exprs {
exprs = append(exprs, e.String())
}
return exprs
}
func (idx *Index) IsUnique() bool {
return idx.Unique
}
func (idx *Index) Comment() string {
return idx.CommentStr
}
func (idx *Index) IndexType() string {
if len(idx.DriverName) > 0 {
return idx.DriverName
}
return "BTREE" // fake but so are you
}
// NewLookup implements the interface sql.Index.
func (idx *Index) NewLookup(ctx *sql.Context, ranges ...sql.Range) (sql.IndexLookup, error) {
if idx.CommentStr == CommentPreventingIndexBuilding {
return nil, nil
}
if len(ranges) == 0 {
return nil, nil
}
if len(ranges[0]) != len(idx.Exprs) {
return nil, fmt.Errorf("expected different key count: %s=>%d/%d", idx.Name, len(idx.Exprs), len(ranges[0]))
}
var rangeCollectionExpr sql.Expression
for _, rang := range ranges {
var rangeExpr sql.Expression
for i, rce := range rang {
var rangeColumnExpr sql.Expression
switch rce.Type() {
// Both Empty and All may seem like strange inclusions, but if only one range is given we need some
// expression to evaluate, otherwise our expression would be a nil expression which would panic.
case sql.RangeType_Empty:
rangeColumnExpr = expression.NewEquals(expression.NewLiteral(1, sql.Int8), expression.NewLiteral(2, sql.Int8))
case sql.RangeType_All:
rangeColumnExpr = expression.NewEquals(expression.NewLiteral(1, sql.Int8), expression.NewLiteral(1, sql.Int8))
case sql.RangeType_GreaterThan:
lit, typ := getType(sql.GetRangeCutKey(rce.LowerBound))
rangeColumnExpr = expression.NewNullSafeGreaterThan(idx.Exprs[i], expression.NewLiteral(lit, typ))
case sql.RangeType_GreaterOrEqual:
lit, typ := getType(sql.GetRangeCutKey(rce.LowerBound))
rangeColumnExpr = expression.NewNullSafeGreaterThanOrEqual(idx.Exprs[i], expression.NewLiteral(lit, typ))
case sql.RangeType_LessThan:
lit, typ := getType(sql.GetRangeCutKey(rce.UpperBound))
rangeColumnExpr = expression.NewNullSafeLessThan(idx.Exprs[i], expression.NewLiteral(lit, typ))
case sql.RangeType_LessOrEqual:
lit, typ := getType(sql.GetRangeCutKey(rce.UpperBound))
rangeColumnExpr = expression.NewNullSafeLessThanOrEqual(idx.Exprs[i], expression.NewLiteral(lit, typ))
case sql.RangeType_ClosedClosed:
if ok, err := rce.RepresentsEquals(); err != nil {
return nil, err
} else if ok {
lit, typ := getType(sql.GetRangeCutKey(rce.LowerBound))
if typ == sql.Null {
rangeColumnExpr = expression.NewIsNull(idx.Exprs[i])
} else {
rangeColumnExpr = expression.NewNullSafeEquals(idx.Exprs[i], expression.NewLiteral(lit, typ))
}
} else {
lowLit, lowTyp := getType(sql.GetRangeCutKey(rce.LowerBound))
upLit, upTyp := getType(sql.GetRangeCutKey(rce.UpperBound))
rangeColumnExpr = and(
expression.NewNullSafeGreaterThanOrEqual(idx.Exprs[i], expression.NewLiteral(lowLit, lowTyp)),
expression.NewNullSafeLessThanOrEqual(idx.Exprs[i], expression.NewLiteral(upLit, upTyp)),
)
}
case sql.RangeType_OpenOpen:
lowLit, lowTyp := getType(sql.GetRangeCutKey(rce.LowerBound))
upLit, upTyp := getType(sql.GetRangeCutKey(rce.UpperBound))
rangeColumnExpr = and(
expression.NewNullSafeGreaterThan(idx.Exprs[i], expression.NewLiteral(lowLit, lowTyp)),
expression.NewNullSafeLessThan(idx.Exprs[i], expression.NewLiteral(upLit, upTyp)),
)
case sql.RangeType_OpenClosed:
lowLit, lowTyp := getType(sql.GetRangeCutKey(rce.LowerBound))
upLit, upTyp := getType(sql.GetRangeCutKey(rce.UpperBound))
rangeColumnExpr = and(
expression.NewNullSafeGreaterThan(idx.Exprs[i], expression.NewLiteral(lowLit, lowTyp)),
expression.NewNullSafeLessThanOrEqual(idx.Exprs[i], expression.NewLiteral(upLit, upTyp)),
)
case sql.RangeType_ClosedOpen:
lowLit, lowTyp := getType(sql.GetRangeCutKey(rce.LowerBound))
upLit, upTyp := getType(sql.GetRangeCutKey(rce.UpperBound))
rangeColumnExpr = and(
expression.NewNullSafeGreaterThanOrEqual(idx.Exprs[i], expression.NewLiteral(lowLit, lowTyp)),
expression.NewNullSafeLessThan(idx.Exprs[i], expression.NewLiteral(upLit, upTyp)),
)
}
rangeExpr = and(rangeExpr, rangeColumnExpr)
}
rangeCollectionExpr = or(rangeCollectionExpr, rangeExpr)
}
return NewIndexLookup(ctx, idx, rangeCollectionExpr, ranges...), nil
}
// ColumnExpressionTypes implements the interface sql.Index.
func (idx *Index) ColumnExpressionTypes(*sql.Context) []sql.ColumnExpressionType {
cets := make([]sql.ColumnExpressionType, len(idx.Exprs))
for i, expr := range idx.Exprs {
cets[i] = sql.ColumnExpressionType{
Expression: expr.String(),
Type: expr.Type(),
}
}
return cets
}
func (idx *Index) ID() string {
if len(idx.Name) > 0 {
return idx.Name
}
if len(idx.Exprs) == 1 {
return idx.Exprs[0].String()
}
var parts = make([]string, len(idx.Exprs))
for i, e := range idx.Exprs {
parts[i] = e.String()
}
return "(" + strings.Join(parts, ", ") + ")"
}
func (idx *Index) Table() string { return idx.TableName }
// ExpressionsIndex is an index made out of one or more expressions (usually field expressions), linked to a Table.
type ExpressionsIndex interface {
sql.Index
MemTable() *Table
ColumnExpressions() []sql.Expression
}
func getType(val interface{}) (interface{}, sql.Type) {
switch val := val.(type) {
case int:
return int64(val), sql.Int64
case uint:
return int64(val), sql.Int64
case int8:
return int64(val), sql.Int64
case uint8:
return int64(val), sql.Int64
case int16:
return int64(val), sql.Int64
case uint16:
return int64(val), sql.Int64
case int32:
return int64(val), sql.Int64
case uint32:
return int64(val), sql.Int64
case int64:
return int64(val), sql.Int64
case uint64:
return int64(val), sql.Int64
case float32:
return float64(val), sql.Float64
case float64:
return float64(val), sql.Float64
case string:
return val, sql.LongText
case nil:
return nil, sql.Null
case time.Time:
return val, sql.Datetime
default:
panic(fmt.Sprintf("Unsupported type for %v of type %T", val, val))
}
}
func or(expressions ...sql.Expression) sql.Expression {
if len(expressions) == 1 {
return expressions[0]
}
if expressions[0] == nil {
return or(expressions[1:]...)
}
return expression.NewOr(expressions[0], or(expressions[1:]...))
}
func and(expressions ...sql.Expression) sql.Expression {
if len(expressions) == 1 {
return expressions[0]
}
if expressions[0] == nil {
return and(expressions[1:]...)
}
return expression.NewAnd(expressions[0], and(expressions[1:]...))
}