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// Copyright 2016 PingCAP, Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
package expression
import (
"strconv"
"strings"
"time"
"unicode"
"github.com/pingcap/errors"
"github.com/pingcap/parser/ast"
"github.com/pingcap/parser/mysql"
"github.com/pingcap/parser/opcode"
"github.com/pingcap/parser/terror"
"github.com/pingcap/tidb/sessionctx"
"github.com/pingcap/tidb/types"
"github.com/pingcap/tidb/types/parser_driver"
"github.com/pingcap/tidb/util/chunk"
"github.com/pingcap/tidb/util/logutil"
"go.uber.org/zap"
"golang.org/x/tools/container/intsets"
)
// cowExprRef is a copy-on-write slice ref util using in `ColumnSubstitute`
// to reduce unnecessary allocation for Expression arguments array
type cowExprRef struct {
ref []Expression
new []Expression
}
// Set will allocate new array if changed flag true
func (c *cowExprRef) Set(i int, changed bool, val Expression) {
if c.new != nil {
c.new[i] = val
return
}
if !changed {
return
}
c.new = make([]Expression, len(c.ref))
copy(c.new, c.ref[:i])
c.new[i] = val
}
// Result return the final reference
func (c *cowExprRef) Result() []Expression {
if c.new != nil {
return c.new
}
return c.ref
}
// Filter the input expressions, append the results to result.
func Filter(result []Expression, input []Expression, filter func(Expression) bool) []Expression {
for _, e := range input {
if filter(e) {
result = append(result, e)
}
}
return result
}
// FilterOutInPlace do the filtering out in place.
// The remained are the ones who doesn't match the filter, storing in the original slice.
// The filteredOut are the ones match the filter, storing in a new slice.
func FilterOutInPlace(input []Expression, filter func(Expression) bool) (remained, filteredOut []Expression) {
for i := len(input) - 1; i >= 0; i-- {
if filter(input[i]) {
filteredOut = append(filteredOut, input[i])
input = append(input[:i], input[i+1:]...)
}
}
return input, filteredOut
}
// ExtractDependentColumns extracts all dependent columns from a virtual column.
func ExtractDependentColumns(expr Expression) []*Column {
// Pre-allocate a slice to reduce allocation, 8 doesn't have special meaning.
result := make([]*Column, 0, 8)
return extractDependentColumns(result, expr)
}
func extractDependentColumns(result []*Column, expr Expression) []*Column {
switch v := expr.(type) {
case *Column:
result = append(result, v)
if v.VirtualExpr != nil {
result = extractDependentColumns(result, v.VirtualExpr)
}
case *ScalarFunction:
for _, arg := range v.GetArgs() {
result = extractDependentColumns(result, arg)
}
}
return result
}
// ExtractColumns extracts all columns from an expression.
func ExtractColumns(expr Expression) []*Column {
// Pre-allocate a slice to reduce allocation, 8 doesn't have special meaning.
result := make([]*Column, 0, 8)
return extractColumns(result, expr, nil)
}
// ExtractCorColumns extracts correlated column from given expression.
func ExtractCorColumns(expr Expression) (cols []*CorrelatedColumn) {
switch v := expr.(type) {
case *CorrelatedColumn:
return []*CorrelatedColumn{v}
case *ScalarFunction:
for _, arg := range v.GetArgs() {
cols = append(cols, ExtractCorColumns(arg)...)
}
}
return
}
// ExtractColumnsFromExpressions is a more efficient version of ExtractColumns for batch operation.
// filter can be nil, or a function to filter the result column.
// It's often observed that the pattern of the caller like this:
//
// cols := ExtractColumns(...)
// for _, col := range cols {
// if xxx(col) {...}
// }
//
// Provide an additional filter argument, this can be done in one step.
// To avoid allocation for cols that not need.
func ExtractColumnsFromExpressions(result []*Column, exprs []Expression, filter func(*Column) bool) []*Column {
for _, expr := range exprs {
result = extractColumns(result, expr, filter)
}
return result
}
func extractColumns(result []*Column, expr Expression, filter func(*Column) bool) []*Column {
switch v := expr.(type) {
case *Column:
if filter == nil || filter(v) {
result = append(result, v)
}
case *ScalarFunction:
for _, arg := range v.GetArgs() {
result = extractColumns(result, arg, filter)
}
}
return result
}
// ExtractColumnSet extracts the different values of `UniqueId` for columns in expressions.
func ExtractColumnSet(exprs []Expression) *intsets.Sparse {
set := &intsets.Sparse{}
for _, expr := range exprs {
extractColumnSet(expr, set)
}
return set
}
func extractColumnSet(expr Expression, set *intsets.Sparse) {
switch v := expr.(type) {
case *Column:
set.Insert(int(v.UniqueID))
case *ScalarFunction:
for _, arg := range v.GetArgs() {
extractColumnSet(arg, set)
}
}
}
func setExprColumnInOperand(expr Expression) Expression {
switch v := expr.(type) {
case *Column:
col := v.Clone().(*Column)
col.InOperand = true
return col
case *ScalarFunction:
args := v.GetArgs()
for i, arg := range args {
args[i] = setExprColumnInOperand(arg)
}
}
return expr
}
// ColumnSubstitute substitutes the columns in filter to expressions in select fields.
// e.g. select * from (select b as a from t) k where a < 10 => select * from (select b as a from t where b < 10) k.
func ColumnSubstitute(expr Expression, schema *Schema, newExprs []Expression) Expression {
_, resExpr := ColumnSubstituteImpl(expr, schema, newExprs)
return resExpr
}
// ColumnSubstituteImpl tries to substitute column expr using newExprs,
// the newFunctionInternal is only called if its child is substituted
func ColumnSubstituteImpl(expr Expression, schema *Schema, newExprs []Expression) (bool, Expression) {
switch v := expr.(type) {
case *Column:
id := schema.ColumnIndex(v)
if id == -1 {
return false, v
}
newExpr := newExprs[id]
if v.InOperand {
newExpr = setExprColumnInOperand(newExpr)
}
return true, newExpr
case *ScalarFunction:
if v.FuncName.L == ast.Cast {
newFunc := v.Clone().(*ScalarFunction)
_, newFunc.GetArgs()[0] = ColumnSubstituteImpl(newFunc.GetArgs()[0], schema, newExprs)
return true, newFunc
}
// cowExprRef is a copy-on-write util, args array allocation happens only
// when expr in args is changed
refExprArr := cowExprRef{v.GetArgs(), nil}
substituted := false
for idx, arg := range v.GetArgs() {
changed, newFuncExpr := ColumnSubstituteImpl(arg, schema, newExprs)
refExprArr.Set(idx, changed, newFuncExpr)
if changed {
substituted = true
}
}
if substituted {
return true, NewFunctionInternal(v.GetCtx(), v.FuncName.L, v.RetType, refExprArr.Result()...)
}
}
return false, expr
}
// getValidPrefix gets a prefix of string which can parsed to a number with base. the minimum base is 2 and the maximum is 36.
func getValidPrefix(s string, base int64) string {
var (
validLen int
upper rune
)
switch {
case base >= 2 && base <= 9:
upper = rune('0' + base)
case base <= 36:
upper = rune('A' + base - 10)
default:
return ""
}
Loop:
for i := 0; i < len(s); i++ {
c := rune(s[i])
switch {
case unicode.IsDigit(c) || unicode.IsLower(c) || unicode.IsUpper(c):
c = unicode.ToUpper(c)
if c < upper {
validLen = i + 1
} else {
break Loop
}
case c == '+' || c == '-':
if i != 0 {
break Loop
}
default:
break Loop
}
}
if validLen > 1 && s[0] == '+' {
return s[1:validLen]
}
return s[:validLen]
}
// SubstituteCorCol2Constant will substitute correlated column to constant value which it contains.
// If the args of one scalar function are all constant, we will substitute it to constant.
func SubstituteCorCol2Constant(expr Expression) (Expression, error) {
switch x := expr.(type) {
case *ScalarFunction:
allConstant := true
newArgs := make([]Expression, 0, len(x.GetArgs()))
for _, arg := range x.GetArgs() {
newArg, err := SubstituteCorCol2Constant(arg)
if err != nil {
return nil, err
}
_, ok := newArg.(*Constant)
newArgs = append(newArgs, newArg)
allConstant = allConstant && ok
}
if allConstant {
val, err := x.Eval(chunk.Row{})
if err != nil {
return nil, err
}
return &Constant{Value: val, RetType: x.GetType()}, nil
}
var newSf Expression
if x.FuncName.L == ast.Cast {
newSf = BuildCastFunction(x.GetCtx(), newArgs[0], x.RetType)
} else {
newSf = NewFunctionInternal(x.GetCtx(), x.FuncName.L, x.GetType(), newArgs...)
}
return newSf, nil
case *CorrelatedColumn:
return &Constant{Value: *x.Data, RetType: x.GetType()}, nil
case *Constant:
if x.DeferredExpr != nil {
newExpr := FoldConstant(x)
return &Constant{Value: newExpr.(*Constant).Value, RetType: x.GetType()}, nil
}
}
return expr, nil
}
// timeZone2Duration converts timezone whose format should satisfy the regular condition
// `(^(+|-)(0?[0-9]|1[0-2]):[0-5]?\d$)|(^+13:00$)` to time.Duration.
func timeZone2Duration(tz string) time.Duration {
sign := 1
if strings.HasPrefix(tz, "-") {
sign = -1
}
i := strings.Index(tz, ":")
h, err := strconv.Atoi(tz[1:i])
terror.Log(err)
m, err := strconv.Atoi(tz[i+1:])
terror.Log(err)
return time.Duration(sign) * (time.Duration(h)*time.Hour + time.Duration(m)*time.Minute)
}
var oppositeOp = map[string]string{
ast.LT: ast.GE,
ast.GE: ast.LT,
ast.GT: ast.LE,
ast.LE: ast.GT,
ast.EQ: ast.NE,
ast.NE: ast.EQ,
ast.LogicOr: ast.LogicAnd,
ast.LogicAnd: ast.LogicOr,
}
// a op b is equal to b symmetricOp a
var symmetricOp = map[opcode.Op]opcode.Op{
opcode.LT: opcode.GT,
opcode.GE: opcode.LE,
opcode.GT: opcode.LT,
opcode.LE: opcode.GE,
opcode.EQ: opcode.EQ,
opcode.NE: opcode.NE,
opcode.NullEQ: opcode.NullEQ,
}
func pushNotAcrossArgs(ctx sessionctx.Context, exprs []Expression, not bool) ([]Expression, bool) {
newExprs := make([]Expression, 0, len(exprs))
flag := false
for _, expr := range exprs {
newExpr, changed := pushNotAcrossExpr(ctx, expr, not)
flag = changed || flag
newExprs = append(newExprs, newExpr)
}
return newExprs, flag
}
// pushNotAcrossExpr try to eliminate the NOT expr in expression tree. It will records whether there's already NOT pushed.
func pushNotAcrossExpr(ctx sessionctx.Context, expr Expression, not bool) (Expression, bool) {
if f, ok := expr.(*ScalarFunction); ok {
switch f.FuncName.L {
case ast.UnaryNot:
return pushNotAcrossExpr(f.GetCtx(), f.GetArgs()[0], !not)
case ast.LT, ast.GE, ast.GT, ast.LE, ast.EQ, ast.NE:
if not {
return NewFunctionInternal(f.GetCtx(), oppositeOp[f.FuncName.L], f.GetType(), f.GetArgs()...), true
}
newArgs, changed := pushNotAcrossArgs(f.GetCtx(), f.GetArgs(), false)
if !changed {
return f, false
}
return NewFunctionInternal(f.GetCtx(), f.FuncName.L, f.GetType(), newArgs...), true
case ast.LogicAnd, ast.LogicOr:
var (
newArgs []Expression
changed bool
)
funcName := f.FuncName.L
if not {
newArgs, _ = pushNotAcrossArgs(f.GetCtx(), f.GetArgs(), true)
funcName = oppositeOp[f.FuncName.L]
changed = true
} else {
newArgs, changed = pushNotAcrossArgs(f.GetCtx(), f.GetArgs(), false)
}
if !changed {
return f, false
}
return NewFunctionInternal(f.GetCtx(), funcName, f.GetType(), newArgs...), true
}
}
if not {
expr = NewFunctionInternal(ctx, ast.UnaryNot, types.NewFieldType(mysql.TypeTiny), expr)
}
return expr, not
}
// PushDownNot pushes the `not` function down to the expression's arguments.
func PushDownNot(ctx sessionctx.Context, expr Expression) Expression {
newExpr, _ := pushNotAcrossExpr(ctx, expr, false)
return newExpr
}
// Contains tests if `exprs` contains `e`.
func Contains(exprs []Expression, e Expression) bool {
for _, expr := range exprs {
if e == expr {
return true
}
}
return false
}
// ExtractFiltersFromDNFs checks whether the cond is DNF. If so, it will get the extracted part and the remained part.
// The original DNF will be replaced by the remained part or just be deleted if remained part is nil.
// And the extracted part will be appended to the end of the orignal slice.
func ExtractFiltersFromDNFs(ctx sessionctx.Context, conditions []Expression) []Expression {
var allExtracted []Expression
for i := len(conditions) - 1; i >= 0; i-- {
if sf, ok := conditions[i].(*ScalarFunction); ok && sf.FuncName.L == ast.LogicOr {
extracted, remained := extractFiltersFromDNF(ctx, sf)
allExtracted = append(allExtracted, extracted...)
if remained == nil {
conditions = append(conditions[:i], conditions[i+1:]...)
} else {
conditions[i] = remained
}
}
}
return append(conditions, allExtracted...)
}
// extractFiltersFromDNF extracts the same condition that occurs in every DNF item and remove them from dnf leaves.
func extractFiltersFromDNF(ctx sessionctx.Context, dnfFunc *ScalarFunction) ([]Expression, Expression) {
dnfItems := FlattenDNFConditions(dnfFunc)
sc := ctx.GetSessionVars().StmtCtx
codeMap := make(map[string]int)
hashcode2Expr := make(map[string]Expression)
for i, dnfItem := range dnfItems {
innerMap := make(map[string]struct{})
cnfItems := SplitCNFItems(dnfItem)
for _, cnfItem := range cnfItems {
code := cnfItem.HashCode(sc)
if i == 0 {
codeMap[string(code)] = 1
hashcode2Expr[string(code)] = cnfItem
} else if _, ok := codeMap[string(code)]; ok {
// We need this check because there may be the case like `select * from t, t1 where (t.a=t1.a and t.a=t1.a) or (something).
// We should make sure that the two `t.a=t1.a` contributes only once.
// TODO: do this out of this function.
if _, ok = innerMap[string(code)]; !ok {
codeMap[string(code)]++
innerMap[string(code)] = struct{}{}
}
}
}
}
// We should make sure that this item occurs in every DNF item.
for hashcode, cnt := range codeMap {
if cnt < len(dnfItems) {
delete(hashcode2Expr, hashcode)
}
}
if len(hashcode2Expr) == 0 {
return nil, dnfFunc
}
newDNFItems := make([]Expression, 0, len(dnfItems))
onlyNeedExtracted := false
for _, dnfItem := range dnfItems {
cnfItems := SplitCNFItems(dnfItem)
newCNFItems := make([]Expression, 0, len(cnfItems))
for _, cnfItem := range cnfItems {
code := cnfItem.HashCode(sc)
_, ok := hashcode2Expr[string(code)]
if !ok {
newCNFItems = append(newCNFItems, cnfItem)
}
}
// If the extracted part is just one leaf of the DNF expression. Then the value of the total DNF expression is
// always the same with the value of the extracted part.
if len(newCNFItems) == 0 {
onlyNeedExtracted = true
break
}
newDNFItems = append(newDNFItems, ComposeCNFCondition(ctx, newCNFItems...))
}
extractedExpr := make([]Expression, 0, len(hashcode2Expr))
for _, expr := range hashcode2Expr {
extractedExpr = append(extractedExpr, expr)
}
if onlyNeedExtracted {
return extractedExpr, nil
}
return extractedExpr, ComposeDNFCondition(ctx, newDNFItems...)
}
// DeriveRelaxedFiltersFromDNF given a DNF expression, derive a relaxed DNF expression which only contains columns
// in specified schema; the derived expression is a superset of original expression, i.e, any tuple satisfying
// the original expression must satisfy the derived expression. Return nil when the derived expression is universal set.
// A running example is: for schema of t1, `(t1.a=1 and t2.a=1) or (t1.a=2 and t2.a=2)` would be derived as
// `t1.a=1 or t1.a=2`, while `t1.a=1 or t2.a=1` would get nil.
func DeriveRelaxedFiltersFromDNF(expr Expression, schema *Schema) Expression {
sf, ok := expr.(*ScalarFunction)
if !ok || sf.FuncName.L != ast.LogicOr {
return nil
}
ctx := sf.GetCtx()
dnfItems := FlattenDNFConditions(sf)
newDNFItems := make([]Expression, 0, len(dnfItems))
for _, dnfItem := range dnfItems {
cnfItems := SplitCNFItems(dnfItem)
newCNFItems := make([]Expression, 0, len(cnfItems))
for _, cnfItem := range cnfItems {
if itemSF, ok := cnfItem.(*ScalarFunction); ok && itemSF.FuncName.L == ast.LogicOr {
relaxedCNFItem := DeriveRelaxedFiltersFromDNF(cnfItem, schema)
if relaxedCNFItem != nil {
newCNFItems = append(newCNFItems, relaxedCNFItem)
}
// If relaxed expression for embedded DNF is universal set, just drop this CNF item
continue
}
// This cnfItem must be simple expression now
// If it cannot be fully covered by schema, just drop this CNF item
if ExprFromSchema(cnfItem, schema) {
newCNFItems = append(newCNFItems, cnfItem)
}
}
// If this DNF item involves no column of specified schema, the relaxed expression must be universal set
if len(newCNFItems) == 0 {
return nil
}
newDNFItems = append(newDNFItems, ComposeCNFCondition(ctx, newCNFItems...))
}
return ComposeDNFCondition(ctx, newDNFItems...)
}
// GetRowLen gets the length if the func is row, returns 1 if not row.
func GetRowLen(e Expression) int {
if f, ok := e.(*ScalarFunction); ok && f.FuncName.L == ast.RowFunc {
return len(f.GetArgs())
}
return 1
}
// CheckArgsNotMultiColumnRow checks the args are not multi-column row.
func CheckArgsNotMultiColumnRow(args ...Expression) error {
for _, arg := range args {
if GetRowLen(arg) != 1 {
return ErrOperandColumns.GenWithStackByArgs(1)
}
}
return nil
}
// GetFuncArg gets the argument of the function at idx.
func GetFuncArg(e Expression, idx int) Expression {
if f, ok := e.(*ScalarFunction); ok {
return f.GetArgs()[idx]
}
return nil
}
// PopRowFirstArg pops the first element and returns the rest of row.
// e.g. After this function (1, 2, 3) becomes (2, 3).
func PopRowFirstArg(ctx sessionctx.Context, e Expression) (ret Expression, err error) {
if f, ok := e.(*ScalarFunction); ok && f.FuncName.L == ast.RowFunc {
args := f.GetArgs()
if len(args) == 2 {
return args[1], nil
}
ret, err = NewFunction(ctx, ast.RowFunc, f.GetType(), args[1:]...)
return ret, err
}
return
}
// exprStack is a stack of expressions.
type exprStack struct {
stack []Expression
}
// pop pops an expression from the stack.
func (s *exprStack) pop() Expression {
if s.len() == 0 {
return nil
}
lastIdx := s.len() - 1
expr := s.stack[lastIdx]
s.stack = s.stack[:lastIdx]
return expr
}
// popN pops n expressions from the stack.
// If n greater than stack length or n is negative, it pops all the expressions.
func (s *exprStack) popN(n int) []Expression {
if n > s.len() || n < 0 {
n = s.len()
}
idx := s.len() - n
exprs := s.stack[idx:]
s.stack = s.stack[:idx]
return exprs
}
// push pushes one expression to the stack.
func (s *exprStack) push(expr Expression) {
s.stack = append(s.stack, expr)
}
// len returns the length of th stack.
func (s *exprStack) len() int {
return len(s.stack)
}
// DatumToConstant generates a Constant expression from a Datum.
func DatumToConstant(d types.Datum, tp byte) *Constant {
return &Constant{Value: d, RetType: types.NewFieldType(tp)}
}
// ParamMarkerExpression generate a getparam function expression.
func ParamMarkerExpression(ctx sessionctx.Context, v *driver.ParamMarkerExpr) (Expression, error) {
useCache := ctx.GetSessionVars().StmtCtx.UseCache
isPointExec := ctx.GetSessionVars().StmtCtx.PointExec
tp := types.NewFieldType(mysql.TypeUnspecified)
types.DefaultParamTypeForValue(v.GetValue(), tp)
value := &Constant{Value: v.Datum, RetType: tp}
if useCache || isPointExec {
value.ParamMarker = &ParamMarker{
order: v.Order,
ctx: ctx,
}
}
return value, nil
}
// DisableParseJSONFlag4Expr disables ParseToJSONFlag for `expr` except Column.
// We should not *PARSE* a string as JSON under some scenarios. ParseToJSONFlag
// is 0 for JSON column yet(as well as JSON correlated column), so we can skip
// it. Moreover, Column.RetType refers to the infoschema, if we modify it, data
// race may happen if another goroutine read from the infoschema at the same
// time.
func DisableParseJSONFlag4Expr(expr Expression) {
if _, isColumn := expr.(*Column); isColumn {
return
}
if _, isCorCol := expr.(*CorrelatedColumn); isCorCol {
return
}
expr.GetType().Flag &= ^mysql.ParseToJSONFlag
}
// ConstructPositionExpr constructs PositionExpr with the given ParamMarkerExpr.
func ConstructPositionExpr(p *driver.ParamMarkerExpr) *ast.PositionExpr {
return &ast.PositionExpr{P: p}
}
// PosFromPositionExpr generates a position value from PositionExpr.
func PosFromPositionExpr(ctx sessionctx.Context, v *ast.PositionExpr) (int, bool, error) {
if v.P == nil {
return v.N, false, nil
}
value, err := ParamMarkerExpression(ctx, v.P.(*driver.ParamMarkerExpr))
if err != nil {
return 0, true, err
}
pos, isNull, err := GetIntFromConstant(ctx, value)
if err != nil || isNull {
return 0, true, err
}
return pos, false, nil
}
// GetStringFromConstant gets a string value from the Constant expression.
func GetStringFromConstant(ctx sessionctx.Context, value Expression) (string, bool, error) {
con, ok := value.(*Constant)
if !ok {
err := errors.Errorf("Not a Constant expression %+v", value)
return "", true, err
}
str, isNull, err := con.EvalString(ctx, chunk.Row{})
if err != nil || isNull {
return "", true, err
}
return str, false, nil
}
// GetIntFromConstant gets an interger value from the Constant expression.
func GetIntFromConstant(ctx sessionctx.Context, value Expression) (int, bool, error) {
str, isNull, err := GetStringFromConstant(ctx, value)
if err != nil || isNull {
return 0, true, err
}
intNum, err := strconv.Atoi(str)
if err != nil {
return 0, true, nil
}
return intNum, false, nil
}
// BuildNotNullExpr wraps up `not(isnull())` for given expression.
func BuildNotNullExpr(ctx sessionctx.Context, expr Expression) Expression {
isNull := NewFunctionInternal(ctx, ast.IsNull, types.NewFieldType(mysql.TypeTiny), expr)
notNull := NewFunctionInternal(ctx, ast.UnaryNot, types.NewFieldType(mysql.TypeTiny), isNull)
return notNull
}
// IsMutableEffectsExpr checks if expr contains function which is mutable or has side effects.
func IsMutableEffectsExpr(expr Expression) bool {
switch x := expr.(type) {
case *ScalarFunction:
if _, ok := mutableEffectsFunctions[x.FuncName.L]; ok {
return true
}
for _, arg := range x.GetArgs() {
if IsMutableEffectsExpr(arg) {
return true
}
}
case *Column:
case *Constant:
if x.DeferredExpr != nil {
return IsMutableEffectsExpr(x.DeferredExpr)
}
}
return false
}
// RemoveDupExprs removes identical exprs. Not that if expr contains functions which
// are mutable or have side effects, we cannot remove it even if it has duplicates.
func RemoveDupExprs(ctx sessionctx.Context, exprs []Expression) []Expression {
res := make([]Expression, 0, len(exprs))
exists := make(map[string]struct{}, len(exprs))
sc := ctx.GetSessionVars().StmtCtx
for _, expr := range exprs {
key := string(expr.HashCode(sc))
if _, ok := exists[key]; !ok || IsMutableEffectsExpr(expr) {
res = append(res, expr)
exists[key] = struct{}{}
}
}
return res
}
// GetUint64FromConstant gets a uint64 from constant expression.
func GetUint64FromConstant(expr Expression) (uint64, bool, bool) {
con, ok := expr.(*Constant)
if !ok {
logutil.BgLogger().Warn("not a constant expression", zap.String("expression", expr.ExplainInfo()))
return 0, false, false
}
dt := con.Value
if con.ParamMarker != nil {
dt = con.ParamMarker.GetUserVar()
} else if con.DeferredExpr != nil {
var err error
dt, err = con.DeferredExpr.Eval(chunk.Row{})
if err != nil {
logutil.BgLogger().Warn("eval deferred expr failed", zap.Error(err))
return 0, false, false
}
}
switch dt.Kind() {
case types.KindNull:
return 0, true, true
case types.KindInt64:
val := dt.GetInt64()
if val < 0 {
return 0, false, false
}
return uint64(val), false, true
case types.KindUint64:
return dt.GetUint64(), false, true
}
return 0, false, false
}
// ContainVirtualColumn checks if the expressions contain a virtual column
func ContainVirtualColumn(exprs []Expression) bool {
for _, expr := range exprs {
switch v := expr.(type) {
case *Column:
if v.VirtualExpr != nil {
return true
}
case *ScalarFunction:
if ContainVirtualColumn(v.GetArgs()) {
return true
}
}
}
return false
}
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