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expression.go
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expression.go
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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,
// 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 expression
import (
"fmt"
"strings"
"github.com/pingcap/errors"
"github.com/pingcap/tidb/pkg/errctx"
exprctx "github.com/pingcap/tidb/pkg/expression/context"
"github.com/pingcap/tidb/pkg/meta/model"
"github.com/pingcap/tidb/pkg/parser/ast"
pmodel "github.com/pingcap/tidb/pkg/parser/model"
"github.com/pingcap/tidb/pkg/parser/mysql"
"github.com/pingcap/tidb/pkg/parser/opcode"
"github.com/pingcap/tidb/pkg/parser/terror"
"github.com/pingcap/tidb/pkg/planner/cascades/base"
"github.com/pingcap/tidb/pkg/types"
"github.com/pingcap/tidb/pkg/util/chunk"
"github.com/pingcap/tidb/pkg/util/generatedexpr"
"github.com/pingcap/tidb/pkg/util/mathutil"
"github.com/pingcap/tidb/pkg/util/size"
"github.com/pingcap/tidb/pkg/util/zeropool"
)
// These are byte flags used for `HashCode()`.
const (
constantFlag byte = 0
columnFlag byte = 1
scalarFunctionFlag byte = 3
parameterFlag byte = 4
ScalarSubQFlag byte = 5
correlatedColumn byte = 6
)
// EvalSimpleAst evaluates a simple ast expression directly.
// This function is used to evaluate some "simple" expressions with limited context.
// See `BuildSimpleExpr` for more details about the differences.
var EvalSimpleAst func(ctx BuildContext, expr ast.ExprNode) (types.Datum, error)
// BuildOptions is used to provide optional settings to build an expression
type BuildOptions struct {
// InputSchema is the input schema for expression to build
InputSchema *Schema
// InputNames is the input names for expression to build
InputNames types.NameSlice
// SourceTableDB is the database that the source table located
SourceTableDB pmodel.CIStr
// SourceTable is used to provide some extra column info.
SourceTable *model.TableInfo
// AllowCastArray specifies whether to allow casting to an array type.
AllowCastArray bool
// TargetFieldType indicates to cast the expression to the target field type if it is not nil
TargetFieldType *types.FieldType
}
// BuildOption is a function to apply optional settings
type BuildOption func(*BuildOptions)
// WithTableInfo specifies table meta for the expression to build.
// When this option is specified, it will use the table meta to resolve column names.
func WithTableInfo(db string, tblInfo *model.TableInfo) BuildOption {
return func(options *BuildOptions) {
options.SourceTableDB = pmodel.NewCIStr(db)
options.SourceTable = tblInfo
}
}
// WithInputSchemaAndNames specifies the input schema and names for the expression to build.
func WithInputSchemaAndNames(schema *Schema, names types.NameSlice, table *model.TableInfo) BuildOption {
return func(options *BuildOptions) {
options.InputSchema = schema
options.InputNames = names
options.SourceTable = table
}
}
// WithAllowCastArray specifies whether to allow casting to an array type.
func WithAllowCastArray(allow bool) BuildOption {
return func(options *BuildOptions) {
options.AllowCastArray = allow
}
}
// WithCastExprTo indicates that we need to the cast the generated expression to the target type
func WithCastExprTo(targetFt *types.FieldType) BuildOption {
return func(options *BuildOptions) {
options.TargetFieldType = targetFt
}
}
// BuildSimpleExpr builds a simple expression from an ast node.
// This function is used to build some "simple" expressions with limited context.
// The below expressions are not supported:
// - Subquery
// - System Variables (e.g. `@tidb_enable_async_commit`)
// - Window functions
// - Aggregate functions
// - Other special functions used in some specified queries such as `GROUPING`, `VALUES` ...
//
// If you want to build a more complex expression, you should use `EvalAstExprWithPlanCtx` or `RewriteAstExprWithPlanCtx`
// in `github.com/pingcap/tidb/pkg/planner/util`. They are more powerful but need planner context to build expressions.
var BuildSimpleExpr func(ctx BuildContext, expr ast.ExprNode, opts ...BuildOption) (Expression, error)
// VecExpr contains all vectorized evaluation methods.
type VecExpr interface {
// Vectorized returns if this expression supports vectorized evaluation.
Vectorized() bool
// VecEvalInt evaluates this expression in a vectorized manner.
VecEvalInt(ctx EvalContext, input *chunk.Chunk, result *chunk.Column) error
// VecEvalReal evaluates this expression in a vectorized manner.
VecEvalReal(ctx EvalContext, input *chunk.Chunk, result *chunk.Column) error
// VecEvalString evaluates this expression in a vectorized manner.
VecEvalString(ctx EvalContext, input *chunk.Chunk, result *chunk.Column) error
// VecEvalDecimal evaluates this expression in a vectorized manner.
VecEvalDecimal(ctx EvalContext, input *chunk.Chunk, result *chunk.Column) error
// VecEvalTime evaluates this expression in a vectorized manner.
VecEvalTime(ctx EvalContext, input *chunk.Chunk, result *chunk.Column) error
// VecEvalDuration evaluates this expression in a vectorized manner.
VecEvalDuration(ctx EvalContext, input *chunk.Chunk, result *chunk.Column) error
// VecEvalJSON evaluates this expression in a vectorized manner.
VecEvalJSON(ctx EvalContext, input *chunk.Chunk, result *chunk.Column) error
// VecEvalBool evaluates this expression in a vectorized manner.
VecEvalVectorFloat32(ctx EvalContext, input *chunk.Chunk, result *chunk.Column) error
}
// TraverseAction define the interface for action when traversing down an expression.
type TraverseAction interface {
Transform(Expression) Expression
}
// ConstLevel indicates the const level for an expression
type ConstLevel uint
const (
// ConstNone indicates the expression is not a constant expression.
// The evaluation result may be different for different input rows.
// e.g. `col_a * 2`, `substring(col_b, 5, 3)`.
ConstNone ConstLevel = iota
// ConstOnlyInContext indicates the expression is only a constant for a same context.
// This is mainly for Plan Cache, e.g. `prepare st from 'select * from t where a<1+?'`, where
// the value of `?` may change between different Contexts (executions).
ConstOnlyInContext
// ConstStrict indicates the expression is a constant expression.
// The evaluation result is always the same no matter the input context or rows.
// e.g. `1 + 2`, `substring("TiDB SQL Tutorial", 5, 3) + 'abcde'`
ConstStrict
)
// Expression represents all scalar expression in SQL.
type Expression interface {
VecExpr
CollationInfo
base.HashEquals
Traverse(TraverseAction) Expression
// Eval evaluates an expression through a row.
Eval(ctx EvalContext, row chunk.Row) (types.Datum, error)
// EvalInt returns the int64 representation of expression.
EvalInt(ctx EvalContext, row chunk.Row) (val int64, isNull bool, err error)
// EvalReal returns the float64 representation of expression.
EvalReal(ctx EvalContext, row chunk.Row) (val float64, isNull bool, err error)
// EvalString returns the string representation of expression.
EvalString(ctx EvalContext, row chunk.Row) (val string, isNull bool, err error)
// EvalDecimal returns the decimal representation of expression.
EvalDecimal(ctx EvalContext, row chunk.Row) (val *types.MyDecimal, isNull bool, err error)
// EvalTime returns the DATE/DATETIME/TIMESTAMP representation of expression.
EvalTime(ctx EvalContext, row chunk.Row) (val types.Time, isNull bool, err error)
// EvalDuration returns the duration representation of expression.
EvalDuration(ctx EvalContext, row chunk.Row) (val types.Duration, isNull bool, err error)
// EvalJSON returns the JSON representation of expression.
EvalJSON(ctx EvalContext, row chunk.Row) (val types.BinaryJSON, isNull bool, err error)
// EvalVectorFloat32 returns the VectorFloat32 representation of expression.
EvalVectorFloat32(ctx EvalContext, row chunk.Row) (val types.VectorFloat32, isNull bool, err error)
// GetType gets the type that the expression returns.
GetType(ctx EvalContext) *types.FieldType
// Clone copies an expression totally.
Clone() Expression
// Equal checks whether two expressions are equal.
Equal(ctx EvalContext, e Expression) bool
// IsCorrelated checks if this expression has correlated key.
IsCorrelated() bool
// ConstLevel returns the const level of the expression.
ConstLevel() ConstLevel
// Decorrelate try to decorrelate the expression by schema.
Decorrelate(schema *Schema) Expression
// ResolveIndices resolves indices by the given schema. It will copy the original expression and return the copied one.
ResolveIndices(schema *Schema) (Expression, error)
// resolveIndices is called inside the `ResolveIndices` It will perform on the expression itself.
resolveIndices(schema *Schema) error
// ResolveIndicesByVirtualExpr resolves indices by the given schema in terms of virtual expression. It will copy the original expression and return the copied one.
ResolveIndicesByVirtualExpr(ctx EvalContext, schema *Schema) (Expression, bool)
// resolveIndicesByVirtualExpr is called inside the `ResolveIndicesByVirtualExpr` It will perform on the expression itself.
resolveIndicesByVirtualExpr(ctx EvalContext, schema *Schema) bool
// RemapColumn remaps columns with provided mapping and returns new expression
RemapColumn(map[int64]*Column) (Expression, error)
// ExplainInfo returns operator information to be explained.
ExplainInfo(ctx EvalContext) string
// ExplainNormalizedInfo returns operator normalized information for generating digest.
ExplainNormalizedInfo() string
// ExplainNormalizedInfo4InList returns operator normalized information for plan digest.
ExplainNormalizedInfo4InList() string
// HashCode creates the hashcode for expression which can be used to identify itself from other expression.
// It generated as the following:
// Constant: ConstantFlag+encoded value
// Column: ColumnFlag+encoded value
// ScalarFunction: SFFlag+encoded function name + encoded arg_1 + encoded arg_2 + ...
HashCode() []byte
// CanonicalHashCode creates the canonical hashcode for expression.
// Different with `HashCode`, this method will produce the same hashcode for expressions with the same semantic.
// For example, `a + b` and `b + a` have the same return value of this method.
CanonicalHashCode() []byte
// MemoryUsage return the memory usage of Expression
MemoryUsage() int64
StringerWithCtx
}
// CNFExprs stands for a CNF expression.
type CNFExprs []Expression
// Clone clones itself.
func (e CNFExprs) Clone() CNFExprs {
cnf := make(CNFExprs, 0, len(e))
for _, expr := range e {
cnf = append(cnf, expr.Clone())
}
return cnf
}
// Shallow makes a shallow copy of itself.
func (e CNFExprs) Shallow() CNFExprs {
cnf := make(CNFExprs, 0, len(e))
cnf = append(cnf, e...)
return cnf
}
func isColumnInOperand(c *Column) bool {
return c.InOperand
}
// IsEQCondFromIn checks if an expression is equal condition converted from `[not] in (subq)`.
func IsEQCondFromIn(expr Expression) bool {
sf, ok := expr.(*ScalarFunction)
if !ok || sf.FuncName.L != ast.EQ {
return false
}
cols := make([]*Column, 0, 1)
cols = ExtractColumnsFromExpressions(cols, sf.GetArgs(), isColumnInOperand)
return len(cols) > 0
}
// ExprNotNull checks if an expression is possible to be null.
func ExprNotNull(ctx EvalContext, expr Expression) bool {
if c, ok := expr.(*Constant); ok {
return !c.Value.IsNull()
}
// For ScalarFunction, the result would not be correct until we support maintaining
// NotNull flag for it.
return mysql.HasNotNullFlag(expr.GetType(ctx).GetFlag())
}
// EvalBool evaluates expression list to a boolean value. The first returned value
// indicates bool result of the expression list, the second returned value indicates
// whether the result of the expression list is null, it can only be true when the
// first returned values is false.
func EvalBool(ctx EvalContext, exprList CNFExprs, row chunk.Row) (bool, bool, error) {
hasNull := false
tc := typeCtx(ctx)
for _, expr := range exprList {
data, err := expr.Eval(ctx, row)
if err != nil {
return false, false, err
}
if data.IsNull() {
// For queries like `select a in (select a from s where t.b = s.b) from t`,
// if result of `t.a = s.a` is null, we cannot return immediately until
// we have checked if `t.b = s.b` is null or false, because it means
// subquery is empty, and we should return false as the result of the whole
// exprList in that case, instead of null.
if !IsEQCondFromIn(expr) {
return false, false, nil
}
hasNull = true
continue
}
i, err := data.ToBool(tc)
if err != nil {
return false, false, err
}
if i == 0 {
return false, false, nil
}
}
if hasNull {
return false, true, nil
}
return true, false, nil
}
var (
defaultChunkSize = 1024
selPool = zeropool.New[[]int](func() []int {
return make([]int, defaultChunkSize)
})
zeroPool = zeropool.New[[]int8](func() []int8 {
return make([]int8, defaultChunkSize)
})
)
func allocSelSlice(n int) []int {
if n > defaultChunkSize {
return make([]int, n)
}
return selPool.Get()
}
func deallocateSelSlice(sel []int) {
if cap(sel) <= defaultChunkSize {
selPool.Put(sel)
}
}
func allocZeroSlice(n int) []int8 {
if n > defaultChunkSize {
return make([]int8, n)
}
return zeroPool.Get()
}
func deallocateZeroSlice(isZero []int8) {
if cap(isZero) <= defaultChunkSize {
zeroPool.Put(isZero)
}
}
// VecEvalBool does the same thing as EvalBool but it works in a vectorized manner.
func VecEvalBool(ctx EvalContext, vecEnabled bool, exprList CNFExprs, input *chunk.Chunk, selected, nulls []bool) ([]bool, []bool, error) {
// If input.Sel() != nil, we will call input.SetSel(nil) to clear the sel slice in input chunk.
// After the function finished, then we reset the input.Sel().
// The caller will handle the input.Sel() and selected slices.
defer input.SetSel(input.Sel())
input.SetSel(nil)
n := input.NumRows()
selected = selected[:0]
nulls = nulls[:0]
for i := 0; i < n; i++ {
selected = append(selected, false)
nulls = append(nulls, false)
}
sel := allocSelSlice(n)
defer deallocateSelSlice(sel)
sel = sel[:0]
for i := 0; i < n; i++ {
sel = append(sel, i)
}
input.SetSel(sel)
// In isZero slice, -1 means Null, 0 means zero, 1 means not zero
isZero := allocZeroSlice(n)
defer deallocateZeroSlice(isZero)
for _, expr := range exprList {
tp := expr.GetType(ctx)
eType := tp.EvalType()
if CanImplicitEvalReal(expr) {
eType = types.ETReal
}
buf, err := globalColumnAllocator.get()
if err != nil {
return nil, nil, err
}
// Take the implicit evalReal path if possible.
if CanImplicitEvalReal(expr) {
if err := implicitEvalReal(ctx, vecEnabled, expr, input, buf); err != nil {
return nil, nil, err
}
} else if err := EvalExpr(ctx, vecEnabled, expr, eType, input, buf); err != nil {
return nil, nil, err
}
err = toBool(typeCtx(ctx), tp, eType, buf, sel, isZero)
if err != nil {
return nil, nil, err
}
j := 0
isEQCondFromIn := IsEQCondFromIn(expr)
for i := range sel {
if isZero[i] == -1 {
if eType != types.ETInt && !isEQCondFromIn {
continue
}
// In this case, we set this row to null and let it pass this filter.
// The null flag may be set to false later by other expressions in some cases.
nulls[sel[i]] = true
sel[j] = sel[i]
j++
continue
}
if isZero[i] == 0 {
continue
}
sel[j] = sel[i] // this row passes this filter
j++
}
sel = sel[:j]
input.SetSel(sel)
globalColumnAllocator.put(buf)
}
for _, i := range sel {
if !nulls[i] {
selected[i] = true
}
}
return selected, nulls, nil
}
func toBool(tc types.Context, tp *types.FieldType, eType types.EvalType, buf *chunk.Column, sel []int, isZero []int8) error {
switch eType {
case types.ETInt:
i64s := buf.Int64s()
for i := range sel {
if buf.IsNull(i) {
isZero[i] = -1
} else {
if i64s[i] == 0 {
isZero[i] = 0
} else {
isZero[i] = 1
}
}
}
case types.ETReal:
f64s := buf.Float64s()
for i := range sel {
if buf.IsNull(i) {
isZero[i] = -1
} else {
if f64s[i] == 0 {
isZero[i] = 0
} else {
isZero[i] = 1
}
}
}
case types.ETDuration:
d64s := buf.GoDurations()
for i := range sel {
if buf.IsNull(i) {
isZero[i] = -1
} else {
if d64s[i] == 0 {
isZero[i] = 0
} else {
isZero[i] = 1
}
}
}
case types.ETDatetime, types.ETTimestamp:
t64s := buf.Times()
for i := range sel {
if buf.IsNull(i) {
isZero[i] = -1
} else {
if t64s[i].IsZero() {
isZero[i] = 0
} else {
isZero[i] = 1
}
}
}
case types.ETString:
for i := range sel {
if buf.IsNull(i) {
isZero[i] = -1
} else {
var fVal float64
var err error
sVal := buf.GetString(i)
if tp.Hybrid() {
switch tp.GetType() {
case mysql.TypeSet, mysql.TypeEnum:
fVal = float64(len(sVal))
if fVal == 0 {
// The elements listed in the column specification are assigned index numbers, beginning
// with 1. The index value of the empty string error value (distinguish from a "normal"
// empty string) is 0. Thus we need to check whether it's an empty string error value when
// `fVal==0`.
for idx, elem := range tp.GetElems() {
if elem == sVal {
fVal = float64(idx + 1)
break
}
}
}
case mysql.TypeBit:
var bl types.BinaryLiteral = buf.GetBytes(i)
iVal, err := bl.ToInt(tc)
if err != nil {
return err
}
fVal = float64(iVal)
}
} else {
fVal, err = types.StrToFloat(tc, sVal, false)
if err != nil {
return err
}
}
if fVal == 0 {
isZero[i] = 0
} else {
isZero[i] = 1
}
}
}
case types.ETDecimal:
d64s := buf.Decimals()
for i := range sel {
if buf.IsNull(i) {
isZero[i] = -1
} else {
if d64s[i].IsZero() {
isZero[i] = 0
} else {
isZero[i] = 1
}
}
}
case types.ETJson:
for i := range sel {
if buf.IsNull(i) {
isZero[i] = -1
} else {
if buf.GetJSON(i).IsZero() {
isZero[i] = 0
} else {
isZero[i] = 1
}
}
}
case types.ETVectorFloat32:
for i := range sel {
if buf.IsNull(i) {
isZero[i] = -1
} else {
if buf.GetVectorFloat32(i).IsZeroValue() {
isZero[i] = 0
} else {
isZero[i] = 1
}
}
}
default:
return errors.Errorf("unsupported type %s during evaluation", eType)
}
return nil
}
func implicitEvalReal(ctx EvalContext, vecEnabled bool, expr Expression, input *chunk.Chunk, result *chunk.Column) (err error) {
if expr.Vectorized() && vecEnabled {
err = expr.VecEvalReal(ctx, input, result)
} else {
ind, n := 0, input.NumRows()
iter := chunk.NewIterator4Chunk(input)
result.ResizeFloat64(n, false)
f64s := result.Float64s()
for it := iter.Begin(); it != iter.End(); it = iter.Next() {
value, isNull, err := expr.EvalReal(ctx, it)
if err != nil {
return err
}
if isNull {
result.SetNull(ind, isNull)
} else {
f64s[ind] = value
}
ind++
}
}
return
}
// EvalExpr evaluates this expr according to its type.
// And it selects the method for evaluating expression based on
// the environment variables and whether the expression can be vectorized.
// Note: the input argument `evalType` is needed because of that when `expr` is
// of the hybrid type(ENUM/SET/BIT), we need the invoker decide the actual EvalType.
func EvalExpr(ctx EvalContext, vecEnabled bool, expr Expression, evalType types.EvalType, input *chunk.Chunk, result *chunk.Column) (err error) {
if expr.Vectorized() && vecEnabled {
switch evalType {
case types.ETInt:
err = expr.VecEvalInt(ctx, input, result)
case types.ETReal:
err = expr.VecEvalReal(ctx, input, result)
case types.ETDuration:
err = expr.VecEvalDuration(ctx, input, result)
case types.ETDatetime, types.ETTimestamp:
err = expr.VecEvalTime(ctx, input, result)
case types.ETString:
err = expr.VecEvalString(ctx, input, result)
case types.ETJson:
err = expr.VecEvalJSON(ctx, input, result)
case types.ETVectorFloat32:
err = expr.VecEvalVectorFloat32(ctx, input, result)
case types.ETDecimal:
err = expr.VecEvalDecimal(ctx, input, result)
default:
err = errors.Errorf("unsupported type %s during evaluation", evalType)
}
} else {
ind, n := 0, input.NumRows()
iter := chunk.NewIterator4Chunk(input)
switch evalType {
case types.ETInt:
result.ResizeInt64(n, false)
i64s := result.Int64s()
for it := iter.Begin(); it != iter.End(); it = iter.Next() {
value, isNull, err := expr.EvalInt(ctx, it)
if err != nil {
return err
}
if isNull {
result.SetNull(ind, isNull)
} else {
i64s[ind] = value
}
ind++
}
case types.ETReal:
result.ResizeFloat64(n, false)
f64s := result.Float64s()
for it := iter.Begin(); it != iter.End(); it = iter.Next() {
value, isNull, err := expr.EvalReal(ctx, it)
if err != nil {
return err
}
if isNull {
result.SetNull(ind, isNull)
} else {
f64s[ind] = value
}
ind++
}
case types.ETDuration:
result.ResizeGoDuration(n, false)
d64s := result.GoDurations()
for it := iter.Begin(); it != iter.End(); it = iter.Next() {
value, isNull, err := expr.EvalDuration(ctx, it)
if err != nil {
return err
}
if isNull {
result.SetNull(ind, isNull)
} else {
d64s[ind] = value.Duration
}
ind++
}
case types.ETDatetime, types.ETTimestamp:
result.ResizeTime(n, false)
t64s := result.Times()
for it := iter.Begin(); it != iter.End(); it = iter.Next() {
value, isNull, err := expr.EvalTime(ctx, it)
if err != nil {
return err
}
if isNull {
result.SetNull(ind, isNull)
} else {
t64s[ind] = value
}
ind++
}
case types.ETString:
result.ReserveString(n)
for it := iter.Begin(); it != iter.End(); it = iter.Next() {
value, isNull, err := expr.EvalString(ctx, it)
if err != nil {
return err
}
if isNull {
result.AppendNull()
} else {
result.AppendString(value)
}
}
case types.ETJson:
result.ReserveJSON(n)
for it := iter.Begin(); it != iter.End(); it = iter.Next() {
value, isNull, err := expr.EvalJSON(ctx, it)
if err != nil {
return err
}
if isNull {
result.AppendNull()
} else {
result.AppendJSON(value)
}
}
case types.ETVectorFloat32:
result.ReserveVectorFloat32(n)
for it := iter.Begin(); it != iter.End(); it = iter.Next() {
value, isNull, err := expr.EvalVectorFloat32(ctx, it)
if err != nil {
return err
}
if isNull {
result.AppendNull()
} else {
result.AppendVectorFloat32(value)
}
}
case types.ETDecimal:
result.ResizeDecimal(n, false)
d64s := result.Decimals()
for it := iter.Begin(); it != iter.End(); it = iter.Next() {
value, isNull, err := expr.EvalDecimal(ctx, it)
if err != nil {
return err
}
if isNull {
result.SetNull(ind, isNull)
} else {
d64s[ind] = *value
}
ind++
}
default:
err = errors.Errorf("unsupported type %s during evaluation", expr.GetType(ctx).EvalType())
}
}
return
}
// composeConditionWithBinaryOp composes condition with binary operator into a balance deep tree, which benefits a lot for pb decoder/encoder.
func composeConditionWithBinaryOp(ctx BuildContext, conditions []Expression, funcName string) Expression {
length := len(conditions)
if length == 0 {
return nil
}
if length == 1 {
return conditions[0]
}
expr := NewFunctionInternal(ctx, funcName,
types.NewFieldType(mysql.TypeTiny),
composeConditionWithBinaryOp(ctx, conditions[:length/2], funcName),
composeConditionWithBinaryOp(ctx, conditions[length/2:], funcName))
return expr
}
// ComposeCNFCondition composes CNF items into a balance deep CNF tree, which benefits a lot for pb decoder/encoder.
func ComposeCNFCondition(ctx BuildContext, conditions ...Expression) Expression {
return composeConditionWithBinaryOp(ctx, conditions, ast.LogicAnd)
}
// ComposeDNFCondition composes DNF items into a balance deep DNF tree.
func ComposeDNFCondition(ctx BuildContext, conditions ...Expression) Expression {
return composeConditionWithBinaryOp(ctx, conditions, ast.LogicOr)
}
func extractBinaryOpItems(conditions *ScalarFunction, funcName string) []Expression {
var ret []Expression
for _, arg := range conditions.GetArgs() {
if sf, ok := arg.(*ScalarFunction); ok && sf.FuncName.L == funcName {
ret = append(ret, extractBinaryOpItems(sf, funcName)...)
} else {
ret = append(ret, arg)
}
}
return ret
}
// FlattenDNFConditions extracts DNF expression's leaf item.
// e.g. or(or(a=1, a=2), or(a=3, a=4)), we'll get [a=1, a=2, a=3, a=4].
func FlattenDNFConditions(DNFCondition *ScalarFunction) []Expression {
return extractBinaryOpItems(DNFCondition, ast.LogicOr)
}
// FlattenCNFConditions extracts CNF expression's leaf item.
// e.g. and(and(a>1, a>2), and(a>3, a>4)), we'll get [a>1, a>2, a>3, a>4].
func FlattenCNFConditions(CNFCondition *ScalarFunction) []Expression {
return extractBinaryOpItems(CNFCondition, ast.LogicAnd)
}
// Assignment represents a set assignment in Update, such as
// Update t set c1 = hex(12), c2 = c3 where c2 = 1
type Assignment struct {
Col *Column
// ColName indicates its original column name in table schema. It's used for outputting helping message when executing meets some errors.
ColName pmodel.CIStr
Expr Expression
// LazyErr is used in statement like `INSERT INTO t1 (a) VALUES (1) ON DUPLICATE KEY UPDATE a= (SELECT b FROM source);`, ErrSubqueryMoreThan1Row
// should be evaluated after the duplicate situation is detected in the executing procedure.
LazyErr error
}
// Clone clones the Assignment.
func (a *Assignment) Clone() *Assignment {
return &Assignment{
Col: a.Col.Clone().(*Column),
ColName: a.ColName,
Expr: a.Expr.Clone(),
LazyErr: a.LazyErr,
}
}
// MemoryUsage return the memory usage of Assignment
func (a *Assignment) MemoryUsage() (sum int64) {
if a == nil {
return
}
sum = size.SizeOfPointer + a.ColName.MemoryUsage() + size.SizeOfInterface*2
if a.Expr != nil {
sum += a.Expr.MemoryUsage()
}
return
}
// VarAssignment represents a variable assignment in Set, such as set global a = 1.
type VarAssignment struct {
Name string
Expr Expression
IsDefault bool
IsGlobal bool
IsSystem bool
ExtendValue *Constant
}
// splitNormalFormItems split CNF(conjunctive normal form) like "a and b and c", or DNF(disjunctive normal form) like "a or b or c"
func splitNormalFormItems(onExpr Expression, funcName string) []Expression {
//nolint: revive
switch v := onExpr.(type) {
case *ScalarFunction:
if v.FuncName.L == funcName {
var ret []Expression
for _, arg := range v.GetArgs() {
ret = append(ret, splitNormalFormItems(arg, funcName)...)
}
return ret
}
}
return []Expression{onExpr}
}
// SplitCNFItems splits CNF items.
// CNF means conjunctive normal form, e.g. "a and b and c".
func SplitCNFItems(onExpr Expression) []Expression {
return splitNormalFormItems(onExpr, ast.LogicAnd)
}
// SplitDNFItems splits DNF items.
// DNF means disjunctive normal form, e.g. "a or b or c".
func SplitDNFItems(onExpr Expression) []Expression {
return splitNormalFormItems(onExpr, ast.LogicOr)
}
// EvaluateExprWithNull sets columns in schema as null and calculate the final result of the scalar function.
// If the Expression is a non-constant value, it means the result is unknown.
func EvaluateExprWithNull(ctx BuildContext, schema *Schema, expr Expression) Expression {
if MaybeOverOptimized4PlanCache(ctx, []Expression{expr}) {
ctx.SetSkipPlanCache(fmt.Sprintf("%v affects null check", expr.StringWithCtx(ctx.GetEvalCtx(), errors.RedactLogDisable)))
}
if ctx.IsInNullRejectCheck() {
expr, _ = evaluateExprWithNullInNullRejectCheck(ctx, schema, expr)
return expr
}
return evaluateExprWithNull(ctx, schema, expr)
}
func evaluateExprWithNull(ctx BuildContext, schema *Schema, expr Expression) Expression {
switch x := expr.(type) {
case *ScalarFunction:
args := make([]Expression, len(x.GetArgs()))
for i, arg := range x.GetArgs() {
args[i] = evaluateExprWithNull(ctx, schema, arg)
}
return NewFunctionInternal(ctx, x.FuncName.L, x.RetType.Clone(), args...)
case *Column:
if !schema.Contains(x) {
return x
}
return &Constant{Value: types.Datum{}, RetType: types.NewFieldType(mysql.TypeNull)}
case *Constant:
if x.DeferredExpr != nil {
return FoldConstant(ctx, x)
}
}
return expr
}
// evaluateExprWithNullInNullRejectCheck sets columns in schema as null and calculate the final result of the scalar function.
// If the Expression is a non-constant value, it means the result is unknown.
// The returned bool values indicates whether the value is influenced by the Null Constant transformed from schema column
// when the value is Null Constant.
func evaluateExprWithNullInNullRejectCheck(ctx BuildContext, schema *Schema, expr Expression) (Expression, bool) {
switch x := expr.(type) {
case *ScalarFunction:
args := make([]Expression, len(x.GetArgs()))
nullFromSets := make([]bool, len(x.GetArgs()))
for i, arg := range x.GetArgs() {
args[i], nullFromSets[i] = evaluateExprWithNullInNullRejectCheck(ctx, schema, arg)
}
allArgsNullFromSet := true
for i := range args {
if cons, ok := args[i].(*Constant); ok && cons.Value.IsNull() && !nullFromSets[i] {
allArgsNullFromSet = false
break
}
}
// If one of the args of `AND` and `OR` are Null Constant from the column schema, and the another argument is Constant, then we should keep it.
// Otherwise, we shouldn't let Null Constant which affected by the column schema participate in computing in `And` and `OR`
// due to the result of `AND` and `OR` are uncertain if one of the arguments is NULL.
if x.FuncName.L == ast.LogicAnd || x.FuncName.L == ast.LogicOr {
hasNonConstantArg := false
for _, arg := range args {
if _, ok := arg.(*Constant); !ok {
hasNonConstantArg = true
break
}
}
if hasNonConstantArg {
for i := range args {
if cons, ok := args[i].(*Constant); ok && cons.Value.IsNull() && nullFromSets[i] {
if x.FuncName.L == ast.LogicAnd {
args[i] = NewOne()
break
}
if x.FuncName.L == ast.LogicOr {
args[i] = NewZero()
break
}
}
}
}
}
c := NewFunctionInternal(ctx, x.FuncName.L, x.RetType.Clone(), args...)
cons, ok := c.(*Constant)
// If the return expr is Null Constant, and all the Null Constant arguments are affected by column schema,
// then we think the result Null Constant is also affected by the column schema
return c, ok && cons.Value.IsNull() && allArgsNullFromSet
case *Column:
if !schema.Contains(x) {