expression

package
v0.1.1-beta.1 Latest Latest
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 Go to latest Published: Jun 30, 2022 License: Apache-2.0, Apache-2.0 Imports: 39 Imported by: 0

Documentation

Index

Constants

This section is empty.

Variables

View Source 
var (

	// CollationStrictnessGroup group collation by strictness
	CollationStrictnessGroup = map[string]int{
		"utf8_general_ci":        1,
		"utf8mb4_general_ci":     1,
		"utf8_unicode_ci":        2,
		"utf8mb4_unicode_ci":     2,
		charset.CollationASCII:   3,
		charset.CollationLatin1:  3,
		charset.CollationUTF8:    3,
		charset.CollationUTF8MB4: 3,
		charset.CollationBin:     4,
	}

	// CollationStrictness indicates the strictness of comparison of the collation. The unequal order in a weak collation also holds in a strict collation.
	// For example, if a != b in a weak collation(e.g. general_ci), then there must be a != b in a strict collation(e.g. _bin).
	// collation group id in value is stricter than collation group id in key
	CollationStrictness = map[int][]int{
		1: {3, 4},
		2: {3, 4},
		3: {4},
		4: {},
	}
)
View Source 
var DeferredFunctions = map[string]struct{}{
	ast.Now:              {},
	ast.RandomBytes:      {},
	ast.CurrentTimestamp: {},
	ast.UTCTime:          {},
	ast.Curtime:          {},
	ast.CurrentTime:      {},
	ast.UTCTimestamp:     {},
	ast.UnixTimestamp:    {},
	ast.Curdate:          {},
	ast.CurrentDate:      {},
	ast.UTCDate:          {},
}

DeferredFunctions stores functions which are foldable but should be deferred as well when plan cache is enabled. Note that, these functions must be foldable at first place, i.e, they are not in `unFoldableFunctions`.

View Source 
var DisableFoldFunctions = map[string]struct{}{
	ast.Benchmark: {},
}

DisableFoldFunctions stores functions which prevent child scope functions from being constant folded. Typically, these functions shall also exist in unFoldableFunctions, to stop from being folded when they themselves are in child scope of an outer function, and the outer function is recursively folding its children.

View Source 
var MaxPropagateColsCnt = 100

MaxPropagateColsCnt means the max number of columns that can participate propagation.

View Source 
var TryFoldFunctions = map[string]struct{}{
	ast.If:       {},
	ast.Ifnull:   {},
	ast.Case:     {},
	ast.LogicAnd: {},
	ast.LogicOr:  {},
	ast.Coalesce: {},
	ast.Interval: {},
}

TryFoldFunctions stores functions which try to fold constant in child scope functions if without errors/warnings, otherwise, the child functions do not fold constant. Note: the function itself should fold constant.

Functions

func CanExprsPushDown 

func CanExprsPushDown(sc *stmtctx.StatementContext, exprs []Expression) bool

CanExprsPushDown return true if all the expr in exprs can be pushed down

func CanImplicitEvalInt 

func CanImplicitEvalInt(expr Expression) bool

CanImplicitEvalInt represents the builtin functions that have an implicit path to evaluate as integer, regardless of the type that type inference decides it to be. This is a nasty way to match the weird behavior of MySQL functions like `dayname()` being implicitly evaluated as integer. See https://github.com/mysql/mysql-server/blob/ee4455a33b10f1b1886044322e4893f587b319ed/sql/item_timefunc.h#L423 for details.

func CanImplicitEvalReal 

func CanImplicitEvalReal(expr Expression) bool

CanImplicitEvalReal represents the builtin functions that have an implicit path to evaluate as real, regardless of the type that type inference decides it to be. This is a nasty way to match the weird behavior of MySQL functions like `dayname()` being implicitly evaluated as real. See https://github.com/mysql/mysql-server/blob/ee4455a33b10f1b1886044322e4893f587b319ed/sql/item_timefunc.h#L423 for details.

func CheckArgsNotMultiColumnRow 

func CheckArgsNotMultiColumnRow(args ...Expression) error

CheckArgsNotMultiColumnRow checks the args are not multi-column row.

func CheckIllegalMixCollation 

func CheckIllegalMixCollation(funcName string, args []Expression, evalType types.EvalType) error

CheckIllegalMixCollation checks illegal mix collation with expressions

func CompareDecimal 

func CompareDecimal(sctx sessionctx.Context, lhsArg, rhsArg Expression, lhsRow, rhsRow chunk.Row) (int64, bool, error)

CompareDecimal compares two decimals.

func CompareDuration 

func CompareDuration(sctx sessionctx.Context, lhsArg, rhsArg Expression, lhsRow, rhsRow chunk.Row) (int64, bool, error)

CompareDuration compares two durations.

func CompareInt 

func CompareInt(sctx sessionctx.Context, lhsArg, rhsArg Expression, lhsRow, rhsRow chunk.Row) (int64, bool, error)

CompareInt compares two integers.

func CompareJSON 

func CompareJSON(sctx sessionctx.Context, lhsArg, rhsArg Expression, lhsRow, rhsRow chunk.Row) (int64, bool, error)

CompareJSON compares two JSONs.

func CompareReal 

func CompareReal(sctx sessionctx.Context, lhsArg, rhsArg Expression, lhsRow, rhsRow chunk.Row) (int64, bool, error)

CompareReal compares two float-point values.

func CompareStringWithCollationInfo 

func CompareStringWithCollationInfo(sctx sessionctx.Context, lhsArg, rhsArg Expression, lhsRow, rhsRow chunk.Row, collation string) (int64, bool, error)

CompareStringWithCollationInfo compares two strings with the specified collation information.

func CompareTime 

func CompareTime(sctx sessionctx.Context, lhsArg, rhsArg Expression, lhsRow, rhsRow chunk.Row) (int64, bool, error)

CompareTime compares two datetime or timestamps.

func ConstructPositionExpr 

func ConstructPositionExpr(p *driver.ParamMarkerExpr) *ast.PositionExpr

ConstructPositionExpr constructs PositionExpr with the given ParamMarkerExpr.

func ContainMutableConst 

func ContainMutableConst(ctx sessionctx.Context, exprs []Expression) bool

ContainMutableConst checks if the expressions contain a lazy constant.

func Contains 

func Contains(exprs []Expression, e Expression) bool

Contains tests if `exprs` contains `e`.

func DeriveCollationFromExprs 

func DeriveCollationFromExprs(ctx sessionctx.Context, exprs ...Expression) (dstCharset, dstCollation string)

DeriveCollationFromExprs derives collation information from these expressions.

func DisableParseJSONFlag4Expr 

func DisableParseJSONFlag4Expr(expr Expression)

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 EvalBool 

func EvalBool(ctx sessionctx.Context, exprList CNFExprs, row chunk.Row) (bool, bool, error)

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 ExprFromSchema 

func ExprFromSchema(expr Expression, schema *Schema) bool

ExprFromSchema checks if all columns of this expression are from the same schema.

func ExtractColumnSet 

func ExtractColumnSet(exprs []Expression) *intsets.Sparse

ExtractColumnSet extracts the different values of `UniqueId` for columns in expressions.

func FindFieldName 

func FindFieldName(names types.NameSlice, astCol *ast.ColumnName) (int, error)

FindFieldName finds the column name from NameSlice.

func GetAccurateCmpType 

func GetAccurateCmpType(lhs, rhs Expression) types.EvalType

GetAccurateCmpType uses a more complex logic to decide the EvalType of the two args when compare with each other than getBaseCmpType does.

func GetIntFromConstant 

func GetIntFromConstant(ctx sessionctx.Context, value Expression) (int, bool, error)

GetIntFromConstant gets an interger value from the Constant expression.

func GetRowLen 

func GetRowLen(e Expression) int

GetRowLen gets the length if the func is row, returns 1 if not row.

func GetStringFromConstant 

func GetStringFromConstant(ctx sessionctx.Context, value Expression) (string, bool, error)

GetStringFromConstant gets a string value from the Constant expression.

func GetUsedList 

func GetUsedList(usedCols []*Column, schema *Schema) []bool

GetUsedList shows whether each column in schema is contained in usedCols.

func HandleOverflowOnSelection 

func HandleOverflowOnSelection(sc *stmtctx.StatementContext, val int64, err error) (int64, error)

HandleOverflowOnSelection handles Overflow errors when evaluating selection filters. We should ignore overflow errors when evaluating selection conditions: 

INSERT INTO t VALUES ("999999999999999999");
SELECT * FROM t WHERE v;

func HasAssignSetVarFunc 

func HasAssignSetVarFunc(expr Expression) bool

HasAssignSetVarFunc checks whether an expression contains SetVar function and assign a value

func HasGetSetVarFunc 

func HasGetSetVarFunc(expr Expression) bool

HasGetSetVarFunc checks whether an expression contains SetVar/GetVar function.

func InferType4ControlFuncs 

func InferType4ControlFuncs(lexp, rexp Expression) *types.FieldType

InferType4ControlFuncs infer result type for builtin IF, IFNULL, NULLIF, LEAD and LAG.

func IsBinaryLiteral 

func IsBinaryLiteral(expr Expression) bool

IsBinaryLiteral checks whether an expression is a binary literal

func IsEQCondFromIn 

func IsEQCondFromIn(expr Expression) bool

IsEQCondFromIn checks if an expression is equal condition converted from `[not] in (subq)`.

func IsMutableEffectsExpr 

func IsMutableEffectsExpr(expr Expression) bool

IsMutableEffectsExpr checks if expr contains function which is mutable or has side effects.

func IsRuntimeConstExpr 

func IsRuntimeConstExpr(expr Expression) bool

IsRuntimeConstExpr checks if a expr can be treated as a constant in **executor**.

func PosFromPositionExpr 

func PosFromPositionExpr(ctx sessionctx.Context, v *ast.PositionExpr) (int, bool, error)

PosFromPositionExpr generates a position value from PositionExpr.

func PropConstOverOuterJoin 

func PropConstOverOuterJoin(ctx sessionctx.Context, joinConds, filterConds []Expression,
	outerSchema, innerSchema *Schema, nullSensitive bool) ([]Expression, []Expression)

PropConstOverOuterJoin propagate constant equal and column equal conditions over outer join. First step is to extract `outerCol = const` from join conditions and filter conditions, and substitute `outerCol` in join conditions with `const`; Second step is to extract `outerCol = innerCol` from join conditions, and derive new join conditions based on this column equal condition and `outerCol` related expressions in join conditions and filter conditions;

func PushDownExprs 

func PushDownExprs(sc *stmtctx.StatementContext, exprs []Expression) (pushed []Expression, remained []Expression)

PushDownExprs split the input exprs into pushed and remained, pushed include all the exprs that can be pushed down

func Quote 

func Quote(str string) string

Quote produce a result that can be used as a properly escaped data value in an SQL statement.

func ResolveType4Between 

func ResolveType4Between(args [3]Expression) types.EvalType

ResolveType4Between resolves eval type for between expression.

func SetBinFlagOrBinStr 

func SetBinFlagOrBinStr(argTp *types.FieldType, resTp *types.FieldType)

SetBinFlagOrBinStr sets resTp to binary string if argTp is a binary string, if not, sets the binary flag of resTp to true if argTp has binary flag.

Types

type Assignment 

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 model.CIStr
	Expr    Expression
}

Assignment represents a set assignment in Update, such as Update t set c1 = hex(12), c2 = c3 where c2 = 1

type CNFExprs 

type CNFExprs []Expression

CNFExprs stands for a CNF expression.

func (CNFExprs) Clone 

func (e CNFExprs) Clone() CNFExprs

Clone clones itself.

func (CNFExprs) Shallow 

func (e CNFExprs) Shallow() CNFExprs

Shallow makes a shallow copy of itself.

type Coercibility 

type Coercibility int

Coercibility values are used to check whether the collation of one item can be coerced to the collation of other. See https://dev.mysql.com/doc/refman/8.0/en/charset-collation-coercibility.html 

const (
	// CoercibilityExplicit is derived from an explicit COLLATE clause.
	CoercibilityExplicit Coercibility = 0
	// CoercibilityNone is derived from the concatenation of two strings with different collations.
	CoercibilityNone Coercibility = 1
	// CoercibilityImplicit is derived from a column or a stored routine parameter or local variable or cast() function.
	CoercibilityImplicit Coercibility = 2
	// CoercibilitySysconst is derived from a “system constant” (the string returned by functions such as USER() or VERSION()).
	CoercibilitySysconst Coercibility = 3
	// CoercibilityCoercible is derived from a literal.
	CoercibilityCoercible Coercibility = 4
	// CoercibilityNumeric is derived from a numeric or temporal value.
	CoercibilityNumeric Coercibility = 5
	// CoercibilityIgnorable is derived from NULL or an expression that is derived from NULL.
	CoercibilityIgnorable Coercibility = 6
)

type CollationInfo 

type CollationInfo interface {
	// HasCoercibility returns if the Coercibility value is initialized.
	HasCoercibility() bool

	// Coercibility returns the coercibility value which is used to check collations.
	Coercibility() Coercibility

	// SetCoercibility sets a specified coercibility for this expression.
	SetCoercibility(val Coercibility)

	// CharsetAndCollation ...
	CharsetAndCollation(ctx sessionctx.Context) (string, string)

	// SetCharsetAndCollation ...
	SetCharsetAndCollation(chs, coll string)
}

CollationInfo contains all interfaces about dealing with collation.

type Column 

type Column struct {
	RetType *types.FieldType
	// ID is used to specify whether this column is ExtraHandleColumn or to access histogram.
	// We'll try to remove it in the future.
	ID int64
	// UniqueID is the unique id of this column.
	UniqueID int64

	// Index is used for execution, to tell the column's position in the given row.
	Index int

	// VirtualExpr is used to save expression for virtual column
	VirtualExpr Expression

	OrigName string
	IsHidden bool

	// IsPrefix indicates whether this column is a prefix column in index.
	//
	// for example:
	// 	pk(col1, col2), index(col1(10)), key: col1(10)_col1_col2 => index's col1 will be true
	// 	pk(col1(10), col2), index(col1), key: col1_col1(10)_col2 => pk's col1 will be true
	IsPrefix bool

	// InOperand indicates whether this column is the inner operand of column equal condition converted
	// from `[not] in (subq)`.
	InOperand bool
	// contains filtered or unexported fields
}

Column represents a column.

func ColInfo2Col 

func ColInfo2Col(cols []*Column, col *model.ColumnInfo) *Column

ColInfo2Col finds the corresponding column of the ColumnInfo in a column slice.

func ExtractColumns 

func ExtractColumns(expr Expression) []*Column

ExtractColumns extracts all columns from an expression.

func ExtractColumnsFromExpressions 

func ExtractColumnsFromExpressions(result []*Column, exprs []Expression, filter func(*Column) bool) []*Column

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 FindPrefixOfIndex 

func FindPrefixOfIndex(cols []*Column, idxColIDs []int64) []*Column

FindPrefixOfIndex will find columns in index by checking the unique id. So it will return at once no matching column is found.

func IndexInfo2Cols 

func IndexInfo2Cols(colInfos []*model.ColumnInfo, cols []*Column, index *model.IndexInfo) ([]*Column, []int)

IndexInfo2Cols gets the corresponding []*Column of the indexInfo's []*IndexColumn, together with a []int containing their lengths. If this index has three IndexColumn that the 1st and 3rd IndexColumn has corresponding *Column, the return value will be [col1, nil, col2].

func IndexInfo2PrefixCols 

func IndexInfo2PrefixCols(colInfos []*model.ColumnInfo, cols []*Column, index *model.IndexInfo) ([]*Column, []int)

IndexInfo2PrefixCols gets the corresponding []*Column of the indexInfo's []*IndexColumn, together with a []int containing their lengths. If this index has three IndexColumn that the 1st and 3rd IndexColumn has corresponding *Column, the return value will be only the 1st corresponding *Column and its length. TODO: Use a struct to represent {*Column, int}. And merge IndexInfo2PrefixCols and IndexInfo2Cols.

func SortColumns 

func SortColumns(cols []*Column) []*Column

SortColumns sort columns based on UniqueID.

func (*Column) CharsetAndCollation 

func (c *Column) CharsetAndCollation(ctx sessionctx.Context) (string, string)

func (*Column) Clone 

func (col *Column) Clone() Expression

Clone implements Expression interface.

func (*Column) Coercibility 

func (col *Column) Coercibility() Coercibility

Coercibility returns the coercibility value which is used to check collations.

func (*Column) ConstItem 

func (col *Column) ConstItem(_ *stmtctx.StatementContext) bool

ConstItem implements Expression interface.

func (*Column) Decorrelate 

func (col *Column) Decorrelate(_ *Schema) Expression

Decorrelate implements Expression interface.

func (*Column) Equal 

func (col *Column) Equal(_ sessionctx.Context, expr Expression) bool

Equal implements Expression interface.

func (*Column) Eval 

func (col *Column) Eval(row chunk.Row) (types.Datum, error)

Eval implements Expression interface.

func (*Column) EvalDecimal 

func (col *Column) EvalDecimal(ctx sessionctx.Context, row chunk.Row) (*types.MyDecimal, bool, error)

EvalDecimal returns decimal representation of Column.

func (*Column) EvalDuration 

func (col *Column) EvalDuration(ctx sessionctx.Context, row chunk.Row) (types.Duration, bool, error)

EvalDuration returns Duration representation of Column.

func (*Column) EvalInt 

func (col *Column) EvalInt(ctx sessionctx.Context, row chunk.Row) (int64, bool, error)

EvalInt returns int representation of Column.

func (*Column) EvalJSON 

func (col *Column) EvalJSON(ctx sessionctx.Context, row chunk.Row) (json.BinaryJSON, bool, error)

EvalJSON returns JSON representation of Column.

func (*Column) EvalReal 

func (col *Column) EvalReal(ctx sessionctx.Context, row chunk.Row) (float64, bool, error)

EvalReal returns real representation of Column.

func (*Column) EvalString 

func (col *Column) EvalString(ctx sessionctx.Context, row chunk.Row) (string, bool, error)

EvalString returns string representation of Column.

func (*Column) EvalTime 

func (col *Column) EvalTime(ctx sessionctx.Context, row chunk.Row) (types.Time, bool, error)

EvalTime returns DATE/DATETIME/TIMESTAMP representation of Column.

func (*Column) EvalVirtualColumn 

func (col *Column) EvalVirtualColumn(row chunk.Row) (types.Datum, error)

EvalVirtualColumn evals the virtual column

func (*Column) GetType 

func (col *Column) GetType() *types.FieldType

GetType implements Expression interface.

func (*Column) HasCoercibility 

func (c *Column) HasCoercibility() bool

func (*Column) HashCode 

func (col *Column) HashCode(_ *stmtctx.StatementContext) []byte

HashCode implements Expression interface.

func (*Column) IsCorrelated 

func (col *Column) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*Column) MarshalJSON 

func (col *Column) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler interface.

func (*Column) ResolveIndices 

func (col *Column) ResolveIndices(schema *Schema) (Expression, error)

ResolveIndices implements Expression interface.

func (*Column) ReverseEval 

func (col *Column) ReverseEval(sc *stmtctx.StatementContext, res types.Datum, rType types.RoundingType) (val types.Datum, err error)

ReverseEval evaluates the only one column value with given function result.

func (*Column) SetCharsetAndCollation 

func (c *Column) SetCharsetAndCollation(chs, coll string)

func (*Column) SetCoercibility 

func (c *Column) SetCoercibility(val Coercibility)

SetCoercibility implements CollationInfo SetCoercibility interface.

func (*Column) String 

func (col *Column) String() string

String implements Stringer interface.

func (*Column) SupportReverseEval 

func (col *Column) SupportReverseEval() bool

SupportReverseEval checks whether the builtinFunc support reverse evaluation.

func (*Column) ToInfo 

func (col *Column) ToInfo() *model.ColumnInfo

ToInfo converts the expression.Column to model.ColumnInfo for casting values, beware it doesn't fill all the fields of the model.ColumnInfo.

func (*Column) VecEvalDecimal 

func (col *Column) VecEvalDecimal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalDecimal evaluates this expression in a vectorized manner.

func (*Column) VecEvalDuration 

func (col *Column) VecEvalDuration(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalDuration evaluates this expression in a vectorized manner.

func (*Column) VecEvalInt 

func (col *Column) VecEvalInt(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalInt evaluates this expression in a vectorized manner.

func (*Column) VecEvalJSON 

func (col *Column) VecEvalJSON(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalJSON evaluates this expression in a vectorized manner.

func (*Column) VecEvalReal 

func (col *Column) VecEvalReal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalReal evaluates this expression in a vectorized manner.

func (*Column) VecEvalString 

func (col *Column) VecEvalString(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalString evaluates this expression in a vectorized manner.

func (*Column) VecEvalTime 

func (col *Column) VecEvalTime(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalTime evaluates this expression in a vectorized manner.

func (*Column) Vectorized 

func (col *Column) Vectorized() bool

Vectorized returns if this expression supports vectorized evaluation.

type CompareFunc 

type CompareFunc = func(sctx sessionctx.Context, lhsArg, rhsArg Expression, lhsRow, rhsRow chunk.Row) (int64, bool, error)

CompareFunc defines the compare function prototype.

type Constant 

type Constant struct {
	Value   types.Datum
	RetType *types.FieldType
	// DeferredExpr holds deferred function in PlanCache cached plan.
	// it's only used to represent non-deterministic functions(see expression.DeferredFunctions)
	// in PlanCache cached plan, so let them can be evaluated until cached item be used.
	DeferredExpr Expression
	// ParamMarker holds param index inside sessionVars.PreparedParams.
	// It's only used to reference a user variable provided in the `EXECUTE` statement or `COM_EXECUTE` binary protocol.
	ParamMarker *ParamMarker
	// contains filtered or unexported fields
}

Constant stands for a constant value.

func NewNull 

func NewNull() *Constant

NewNull stands for null constant.

func NewOne 

func NewOne() *Constant

NewOne stands for a number 1.

func NewZero 

func NewZero() *Constant

NewZero stands for a number 0.

func RefineComparedConstant 

func RefineComparedConstant(ctx sessionctx.Context, targetFieldType types.FieldType, con *Constant, op opcode.Op) (_ *Constant, isExceptional bool)

RefineComparedConstant changes a non-integer constant argument to its ceiling or floor result by the given op. isExceptional indicates whether the 'int column cmp const' might be true/false. If isExceptional is true, ExecptionalVal is returned. Or, CorrectVal is returned. CorrectVal: The computed result. If the constant can be converted to int without exception, return the val. Else return 'con'(the input). ExceptionalVal : It is used to get more information to check whether 'int column cmp const' is true/false 

If the op == LT,LE,GT,GE and it gets an Overflow when converting, return inf/-inf.
If the op == EQ,NullEQ and the constant can never be equal to the int column, return ‘con’(the input, a non-int constant).

func (*Constant) CharsetAndCollation 

func (c *Constant) CharsetAndCollation(ctx sessionctx.Context) (string, string)

func (*Constant) Clone 

func (c *Constant) Clone() Expression

Clone implements Expression interface.

func (*Constant) Coercibility 

func (c *Constant) Coercibility() Coercibility

Coercibility returns the coercibility value which is used to check collations.

func (*Constant) ConstItem 

func (c *Constant) ConstItem(sc *stmtctx.StatementContext) bool

ConstItem implements Expression interface.

func (*Constant) Decorrelate 

func (c *Constant) Decorrelate(_ *Schema) Expression

Decorrelate implements Expression interface.

func (*Constant) Equal 

func (c *Constant) Equal(ctx sessionctx.Context, b Expression) bool

Equal implements Expression interface.

func (*Constant) Eval 

func (c *Constant) Eval(row chunk.Row) (types.Datum, error)

Eval implements Expression interface.

func (*Constant) EvalDecimal 

func (c *Constant) EvalDecimal(ctx sessionctx.Context, row chunk.Row) (*types.MyDecimal, bool, error)

EvalDecimal returns decimal representation of Constant.

func (*Constant) EvalDuration 

func (c *Constant) EvalDuration(ctx sessionctx.Context, row chunk.Row) (val types.Duration, isNull bool, err error)

EvalDuration returns Duration representation of Constant.

func (*Constant) EvalInt 

func (c *Constant) EvalInt(ctx sessionctx.Context, row chunk.Row) (int64, bool, error)

EvalInt returns int representation of Constant.

func (*Constant) EvalJSON 

func (c *Constant) EvalJSON(ctx sessionctx.Context, row chunk.Row) (json.BinaryJSON, bool, error)

EvalJSON returns JSON representation of Constant.

func (*Constant) EvalReal 

func (c *Constant) EvalReal(ctx sessionctx.Context, row chunk.Row) (float64, bool, error)

EvalReal returns real representation of Constant.

func (*Constant) EvalString 

func (c *Constant) EvalString(ctx sessionctx.Context, row chunk.Row) (string, bool, error)

EvalString returns string representation of Constant.

func (*Constant) EvalTime 

func (c *Constant) EvalTime(ctx sessionctx.Context, row chunk.Row) (val types.Time, isNull bool, err error)

EvalTime returns DATE/DATETIME/TIMESTAMP representation of Constant.

func (*Constant) GetType 

func (c *Constant) GetType() *types.FieldType

GetType implements Expression interface.

func (*Constant) HasCoercibility 

func (c *Constant) HasCoercibility() bool

func (*Constant) HashCode 

func (c *Constant) HashCode(sc *stmtctx.StatementContext) []byte

HashCode implements Expression interface.

func (*Constant) IsCorrelated 

func (c *Constant) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*Constant) MarshalJSON 

func (c *Constant) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler interface.

func (*Constant) ResolveIndices 

func (c *Constant) ResolveIndices(_ *Schema) (Expression, error)

ResolveIndices implements Expression interface.

func (*Constant) ReverseEval 

func (c *Constant) ReverseEval(sc *stmtctx.StatementContext, res types.Datum, rType types.RoundingType) (val types.Datum, err error)

ReverseEval evaluates the only one column value with given function result.

func (*Constant) SetCharsetAndCollation 

func (c *Constant) SetCharsetAndCollation(chs, coll string)

func (*Constant) SetCoercibility 

func (c *Constant) SetCoercibility(val Coercibility)

SetCoercibility implements CollationInfo SetCoercibility interface.

func (*Constant) String 

func (c *Constant) String() string

String implements fmt.Stringer interface.

func (*Constant) SupportReverseEval 

func (c *Constant) SupportReverseEval() bool

SupportReverseEval checks whether the builtinFunc support reverse evaluation.

func (*Constant) VecEvalDecimal 

func (c *Constant) VecEvalDecimal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalDecimal evaluates this expression in a vectorized manner.

func (*Constant) VecEvalDuration 

func (c *Constant) VecEvalDuration(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalDuration evaluates this expression in a vectorized manner.

func (*Constant) VecEvalInt 

func (c *Constant) VecEvalInt(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalInt evaluates this expression in a vectorized manner.

func (*Constant) VecEvalJSON 

func (c *Constant) VecEvalJSON(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalJSON evaluates this expression in a vectorized manner.

func (*Constant) VecEvalReal 

func (c *Constant) VecEvalReal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalReal evaluates this expression in a vectorized manner.

func (*Constant) VecEvalString 

func (c *Constant) VecEvalString(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalString evaluates this expression in a vectorized manner.

func (*Constant) VecEvalTime 

func (c *Constant) VecEvalTime(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalTime evaluates this expression in a vectorized manner.

func (*Constant) Vectorized 

func (c *Constant) Vectorized() bool

Vectorized returns if this expression supports vectorized evaluation.

type CorrelatedColumn 

type CorrelatedColumn struct {
	Column

	Data *types.Datum
}

CorrelatedColumn stands for a column in a correlated sub query.

func ExtractCorColumns 

func ExtractCorColumns(expr Expression) (cols []*CorrelatedColumn)

ExtractCorColumns extracts correlated column from given expression.

func (*CorrelatedColumn) CharsetAndCollation 

func (c *CorrelatedColumn) CharsetAndCollation(ctx sessionctx.Context) (string, string)

func (*CorrelatedColumn) Clone 

func (col *CorrelatedColumn) Clone() Expression

Clone implements Expression interface.

func (*CorrelatedColumn) ConstItem 

func (col *CorrelatedColumn) ConstItem(_ *stmtctx.StatementContext) bool

ConstItem implements Expression interface.

func (*CorrelatedColumn) Decorrelate 

func (col *CorrelatedColumn) Decorrelate(schema *Schema) Expression

Decorrelate implements Expression interface.

func (*CorrelatedColumn) Equal 

func (col *CorrelatedColumn) Equal(ctx sessionctx.Context, expr Expression) bool

Equal implements Expression interface.

func (*CorrelatedColumn) Eval 

func (col *CorrelatedColumn) Eval(row chunk.Row) (types.Datum, error)

Eval implements Expression interface.

func (*CorrelatedColumn) EvalDecimal 

func (col *CorrelatedColumn) EvalDecimal(ctx sessionctx.Context, row chunk.Row) (*types.MyDecimal, bool, error)

EvalDecimal returns decimal representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalDuration 

func (col *CorrelatedColumn) EvalDuration(ctx sessionctx.Context, row chunk.Row) (types.Duration, bool, error)

EvalDuration returns Duration representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalInt 

func (col *CorrelatedColumn) EvalInt(ctx sessionctx.Context, row chunk.Row) (int64, bool, error)

EvalInt returns int representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalJSON 

func (col *CorrelatedColumn) EvalJSON(ctx sessionctx.Context, row chunk.Row) (json.BinaryJSON, bool, error)

EvalJSON returns JSON representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalReal 

func (col *CorrelatedColumn) EvalReal(ctx sessionctx.Context, row chunk.Row) (float64, bool, error)

EvalReal returns real representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalString 

func (col *CorrelatedColumn) EvalString(ctx sessionctx.Context, row chunk.Row) (string, bool, error)

EvalString returns string representation of CorrelatedColumn.

func (*CorrelatedColumn) EvalTime 

func (col *CorrelatedColumn) EvalTime(ctx sessionctx.Context, row chunk.Row) (types.Time, bool, error)

EvalTime returns DATE/DATETIME/TIMESTAMP representation of CorrelatedColumn.

func (*CorrelatedColumn) HasCoercibility 

func (c *CorrelatedColumn) HasCoercibility() bool

func (*CorrelatedColumn) IsCorrelated 

func (col *CorrelatedColumn) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*CorrelatedColumn) ResolveIndices 

func (col *CorrelatedColumn) ResolveIndices(_ *Schema) (Expression, error)

ResolveIndices implements Expression interface.

func (*CorrelatedColumn) SetCharsetAndCollation 

func (c *CorrelatedColumn) SetCharsetAndCollation(chs, coll string)

func (*CorrelatedColumn) SetCoercibility 

func (c *CorrelatedColumn) SetCoercibility(val Coercibility)

SetCoercibility implements CollationInfo SetCoercibility interface.

func (*CorrelatedColumn) VecEvalDecimal 

func (col *CorrelatedColumn) VecEvalDecimal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalDecimal evaluates this expression in a vectorized manner.

func (*CorrelatedColumn) VecEvalDuration 

func (col *CorrelatedColumn) VecEvalDuration(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalDuration evaluates this expression in a vectorized manner.

func (*CorrelatedColumn) VecEvalInt 

func (col *CorrelatedColumn) VecEvalInt(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalInt evaluates this expression in a vectorized manner.

func (*CorrelatedColumn) VecEvalJSON 

func (col *CorrelatedColumn) VecEvalJSON(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalJSON evaluates this expression in a vectorized manner.

func (*CorrelatedColumn) VecEvalReal 

func (col *CorrelatedColumn) VecEvalReal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalReal evaluates this expression in a vectorized manner.

func (*CorrelatedColumn) VecEvalString 

func (col *CorrelatedColumn) VecEvalString(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalString evaluates this expression in a vectorized manner.

func (*CorrelatedColumn) VecEvalTime 

func (col *CorrelatedColumn) VecEvalTime(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalTime evaluates this expression in a vectorized manner.

type Expression 

type Expression interface {
	fmt.Stringer
	goJSON.Marshaler
	VecExpr
	ReverseExpr
	CollationInfo

	// Eval evaluates an expression through a row.
	Eval(row chunk.Row) (types.Datum, error)

	// EvalInt returns the int64 representation of expression.
	EvalInt(ctx sessionctx.Context, row chunk.Row) (val int64, isNull bool, err error)

	// EvalReal returns the float64 representation of expression.
	EvalReal(ctx sessionctx.Context, row chunk.Row) (val float64, isNull bool, err error)

	// EvalString returns the string representation of expression.
	EvalString(ctx sessionctx.Context, row chunk.Row) (val string, isNull bool, err error)

	// EvalDecimal returns the decimal representation of expression.
	EvalDecimal(ctx sessionctx.Context, row chunk.Row) (val *types.MyDecimal, isNull bool, err error)

	// EvalTime returns the DATE/DATETIME/TIMESTAMP representation of expression.
	EvalTime(ctx sessionctx.Context, row chunk.Row) (val types.Time, isNull bool, err error)

	// EvalDuration returns the duration representation of expression.
	EvalDuration(ctx sessionctx.Context, row chunk.Row) (val types.Duration, isNull bool, err error)

	// EvalJSON returns the JSON representation of expression.
	EvalJSON(ctx sessionctx.Context, row chunk.Row) (val json.BinaryJSON, isNull bool, err error)

	// GetType gets the type that the expression returns.
	GetType() *types.FieldType

	// Clone copies an expression totally.
	Clone() Expression

	// Equal checks whether two expressions are equal.
	Equal(ctx sessionctx.Context, e Expression) bool

	// IsCorrelated checks if this expression has correlated key.
	IsCorrelated() bool

	// ConstItem checks if this expression is constant item, regardless of query evaluation state.
	// An expression is constant item if it:
	// refers no tables.
	// refers no correlated column.
	// refers no subqueries that refers any tables.
	// refers no non-deterministic functions.
	// refers no statement parameters.
	// refers no param markers when prepare plan cache is enabled.
	ConstItem(sc *stmtctx.StatementContext) bool

	// 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)

	// 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(sc *stmtctx.StatementContext) []byte
	// contains filtered or unexported methods
}

Expression represents all scalar expression in SQL.

func BuildCastFunction 

func BuildCastFunction(ctx sessionctx.Context, expr Expression, tp *types.FieldType) (res Expression)

BuildCastFunction builds a CAST ScalarFunction from the Expression.

func BuildCastFunction4Union 

func BuildCastFunction4Union(ctx sessionctx.Context, expr Expression, tp *types.FieldType) (res Expression)

BuildCastFunction4Union build a implicitly CAST ScalarFunction from the Union Expression.

func BuildNotNullExpr 

func BuildNotNullExpr(ctx sessionctx.Context, expr Expression) Expression

BuildNotNullExpr wraps up `not(isnull())` for given expression.

func Column2Exprs 

func Column2Exprs(cols []*Column) []Expression

Column2Exprs will transfer column slice to expression slice.

func ColumnSubstitute 

func ColumnSubstitute(expr Expression, schema *Schema, newExprs []Expression) Expression

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 ColumnSubstituteImpl 

func ColumnSubstituteImpl(expr Expression, schema *Schema, newExprs []Expression) (bool, Expression)

ColumnSubstituteImpl tries to substitute column expr using newExprs, the newFunctionInternal is only called if its child is substituted

func ComposeCNFCondition 

func ComposeCNFCondition(ctx sessionctx.Context, conditions ...Expression) Expression

ComposeCNFCondition composes CNF items into a balance deep CNF tree, which benefits a lot for pb decoder/encoder.

func ComposeDNFCondition 

func ComposeDNFCondition(ctx sessionctx.Context, conditions ...Expression) Expression

ComposeDNFCondition composes DNF items into a balance deep DNF tree.

func DeriveRelaxedFiltersFromDNF 

func DeriveRelaxedFiltersFromDNF(expr Expression, schema *Schema) Expression

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 EvaluateExprWithNull 

func EvaluateExprWithNull(ctx sessionctx.Context, schema *Schema, expr Expression) Expression

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 ExtractFiltersFromDNFs 

func ExtractFiltersFromDNFs(ctx sessionctx.Context, conditions []Expression) []Expression

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 Filter 

func Filter(result []Expression, input []Expression, filter func(Expression) bool) []Expression

Filter the input expressions, append the results to result.

func FlattenCNFConditions 

func FlattenCNFConditions(CNFCondition *ScalarFunction) []Expression

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 FlattenDNFConditions 

func FlattenDNFConditions(DNFCondition *ScalarFunction) []Expression

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 FoldConstant 

func FoldConstant(expr Expression) Expression

FoldConstant does constant folding optimization on an expression excluding deferred ones.

func GetFuncArg 

func GetFuncArg(e Expression, idx int) Expression

GetFuncArg gets the argument of the function at idx.

func NewFunction 

func NewFunction(ctx sessionctx.Context, funcName string, retType *types.FieldType, args ...Expression) (Expression, error)

NewFunction creates a new scalar function or constant via a constant folding.

func NewFunctionBase 

func NewFunctionBase(ctx sessionctx.Context, funcName string, retType *types.FieldType, args ...Expression) (Expression, error)

NewFunctionBase creates a new scalar function with no constant folding.

func NewFunctionInternal 

func NewFunctionInternal(ctx sessionctx.Context, funcName string, retType *types.FieldType, args ...Expression) Expression

NewFunctionInternal is similar to NewFunction, but do not returns error, should only be used internally.

func NewFunctionTryFold 

func NewFunctionTryFold(ctx sessionctx.Context, funcName string, retType *types.FieldType, args ...Expression) (Expression, error)

NewFunctionTryFold creates a new scalar function with trying constant folding.

func ParamMarkerExpression 

func ParamMarkerExpression(ctx sessionctx.Context, v *driver.ParamMarkerExpr) (Expression, error)

ParamMarkerExpression generate a getparam function expression.

func PopRowFirstArg 

func PopRowFirstArg(ctx sessionctx.Context, e Expression) (ret Expression, err error)

PopRowFirstArg pops the first element and returns the rest of row. e.g. After this function (1, 2, 3) becomes (2, 3).

func PropagateConstant 

func PropagateConstant(ctx sessionctx.Context, conditions []Expression) []Expression

PropagateConstant propagate constant values of deterministic predicates in a condition.

func PushDownNot 

func PushDownNot(ctx sessionctx.Context, expr Expression) Expression

PushDownNot pushes the `not` function down to the expression's arguments.

func RemoveDupExprs 

func RemoveDupExprs(ctx sessionctx.Context, exprs []Expression) []Expression

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; if the plan is going to be cached, we cannot remove expressions containing `?` neither.

func ScalarFuncs2Exprs 

func ScalarFuncs2Exprs(funcs []*ScalarFunction) []Expression

ScalarFuncs2Exprs converts []*ScalarFunction to []Expression.

func SplitCNFItems 

func SplitCNFItems(onExpr Expression) []Expression

SplitCNFItems splits CNF items. CNF means conjunctive normal form, e.g. "a and b and c".

func SplitDNFItems 

func SplitDNFItems(onExpr Expression) []Expression

SplitDNFItems splits DNF items. DNF means disjunctive normal form, e.g. "a or b or c".

func TryPushCastIntoControlFunctionForHybridType 

func TryPushCastIntoControlFunctionForHybridType(ctx sessionctx.Context, expr Expression, tp *types.FieldType) (res Expression)

TryPushCastIntoControlFunctionForHybridType try to push cast into control function for Hybrid Type. If necessary, it will rebuild control function using changed args. When a hybrid type is the output of a control function, the result may be as a numeric type to subsequent calculation We should perform the `Cast` operation early to avoid using the wrong type for calculation For example, the condition `if(1, e, 'a') = 1`, `if` function will output `e` and compare with `1`. If the evaltype is ETString, it will get wrong result. So we can rewrite the condition to `IfInt(1, cast(e as int), cast('a' as int)) = 1` to get the correct result.

func WrapWithCastAsDecimal 

func WrapWithCastAsDecimal(ctx sessionctx.Context, expr Expression) Expression

WrapWithCastAsDecimal wraps `expr` with `cast` if the return type of expr is not type decimal, otherwise, returns `expr` directly.

func WrapWithCastAsDuration 

func WrapWithCastAsDuration(ctx sessionctx.Context, expr Expression) Expression

WrapWithCastAsDuration wraps `expr` with `cast` if the return type of expr is not type duration, otherwise, returns `expr` directly.

func WrapWithCastAsInt 

func WrapWithCastAsInt(ctx sessionctx.Context, expr Expression) Expression

WrapWithCastAsInt wraps `expr` with `cast` if the return type of expr is not type int, otherwise, returns `expr` directly.

func WrapWithCastAsJSON 

func WrapWithCastAsJSON(ctx sessionctx.Context, expr Expression) Expression

WrapWithCastAsJSON wraps `expr` with `cast` if the return type of expr is not type json, otherwise, returns `expr` directly.

func WrapWithCastAsReal 

func WrapWithCastAsReal(ctx sessionctx.Context, expr Expression) Expression

WrapWithCastAsReal wraps `expr` with `cast` if the return type of expr is not type real, otherwise, returns `expr` directly.

func WrapWithCastAsString 

func WrapWithCastAsString(ctx sessionctx.Context, expr Expression) Expression

WrapWithCastAsString wraps `expr` with `cast` if the return type of expr is not type string, otherwise, returns `expr` directly.

func WrapWithCastAsTime 

func WrapWithCastAsTime(ctx sessionctx.Context, expr Expression, tp *types.FieldType) Expression

WrapWithCastAsTime wraps `expr` with `cast` if the return type of expr is not same as type of the specified `tp` , otherwise, returns `expr` directly.

type IntSet 

type IntSet struct {
	// contains filtered or unexported fields
}

IntSet is the int disjoint set.

func NewIntSet 

func NewIntSet(size int) *IntSet

NewIntSet returns a new int disjoint set.

func (*IntSet) FindRoot 

func (m *IntSet) FindRoot(a int) int

FindRoot finds the representative element of the set that `a` belongs to.

func (*IntSet) Union 

func (m *IntSet) Union(a int, b int)

Union unions two sets in int disjoint set.

type KeyInfo 

type KeyInfo []*Column

KeyInfo stores the columns of one unique key or primary key.

func (KeyInfo) Clone 

func (ki KeyInfo) Clone() KeyInfo

Clone copies the entire UniqueKey.

type MysqlRng 

type MysqlRng struct {
	// contains filtered or unexported fields
}

MysqlRng is random number generator and this implementation is ported from MySQL. See https://github.com/tikv/tikv/pull/6117#issuecomment-562489078.

func NewWithSeed 

func NewWithSeed(seed int64) *MysqlRng

NewWithSeed create a rng with random seed.

func NewWithTime 

func NewWithTime() *MysqlRng

NewWithTime create a rng with time stamp.

func (*MysqlRng) Gen 

func (rng *MysqlRng) Gen() float64

Gen will generate random number.

type ParamMarker 

type ParamMarker struct {
	// contains filtered or unexported fields
}

ParamMarker indicates param provided by COM_STMT_EXECUTE.

func (*ParamMarker) GetUserVar 

func (d *ParamMarker) GetUserVar() types.Datum

GetUserVar returns the corresponding user variable presented in the `EXECUTE` statement or `COM_EXECUTE` command.

type PropagateConstantSolver 

type PropagateConstantSolver interface {
	PropagateConstant(ctx sessionctx.Context, conditions []Expression) []Expression
}

PropagateConstantSolver is a constant propagate solver.

type ReverseExpr 

type ReverseExpr interface {
	// SupportReverseEval checks whether the builtinFunc support reverse evaluation.
	SupportReverseEval() bool

	// ReverseEval evaluates the only one column value with given function result.
	ReverseEval(sc *stmtctx.StatementContext, res types.Datum, rType types.RoundingType) (val types.Datum, err error)
}

ReverseExpr contains all resersed evaluation methods.

type ScalarFunction 

type ScalarFunction struct {
	FuncName model.CIStr
	// RetType is the type that ScalarFunction returns.
	// TODO: Implement type inference here, now we use ast's return type temporarily.
	RetType  *types.FieldType
	Function builtinFunc
	// contains filtered or unexported fields
}

ScalarFunction is the function that returns a value.

func (*ScalarFunction) CharsetAndCollation 

func (sf *ScalarFunction) CharsetAndCollation(ctx sessionctx.Context) (string, string)

CharsetAndCollation ...

func (*ScalarFunction) Clone 

func (sf *ScalarFunction) Clone() Expression

Clone implements Expression interface.

func (*ScalarFunction) Coercibility 

func (sf *ScalarFunction) Coercibility() Coercibility

Coercibility returns the coercibility value which is used to check collations.

func (*ScalarFunction) ConstItem 

func (sf *ScalarFunction) ConstItem(sc *stmtctx.StatementContext) bool

ConstItem implements Expression interface.

func (*ScalarFunction) Decorrelate 

func (sf *ScalarFunction) Decorrelate(schema *Schema) Expression

Decorrelate implements Expression interface.

func (*ScalarFunction) Equal 

func (sf *ScalarFunction) Equal(ctx sessionctx.Context, e Expression) bool

Equal implements Expression interface.

func (*ScalarFunction) Eval 

func (sf *ScalarFunction) Eval(row chunk.Row) (d types.Datum, err error)

Eval implements Expression interface.

func (*ScalarFunction) EvalDecimal 

func (sf *ScalarFunction) EvalDecimal(ctx sessionctx.Context, row chunk.Row) (*types.MyDecimal, bool, error)

EvalDecimal implements Expression interface.

func (*ScalarFunction) EvalDuration 

func (sf *ScalarFunction) EvalDuration(ctx sessionctx.Context, row chunk.Row) (types.Duration, bool, error)

EvalDuration implements Expression interface.

func (*ScalarFunction) EvalInt 

func (sf *ScalarFunction) EvalInt(ctx sessionctx.Context, row chunk.Row) (int64, bool, error)

EvalInt implements Expression interface.

func (*ScalarFunction) EvalJSON 

func (sf *ScalarFunction) EvalJSON(ctx sessionctx.Context, row chunk.Row) (json.BinaryJSON, bool, error)

EvalJSON implements Expression interface.

func (*ScalarFunction) EvalReal 

func (sf *ScalarFunction) EvalReal(ctx sessionctx.Context, row chunk.Row) (float64, bool, error)

EvalReal implements Expression interface.

func (*ScalarFunction) EvalString 

func (sf *ScalarFunction) EvalString(ctx sessionctx.Context, row chunk.Row) (string, bool, error)

EvalString implements Expression interface.

func (*ScalarFunction) EvalTime 

func (sf *ScalarFunction) EvalTime(ctx sessionctx.Context, row chunk.Row) (types.Time, bool, error)

EvalTime implements Expression interface.

func (*ScalarFunction) GetArgs 

func (sf *ScalarFunction) GetArgs() []Expression

GetArgs gets arguments of function.

func (*ScalarFunction) GetCtx 

func (sf *ScalarFunction) GetCtx() sessionctx.Context

GetCtx gets the context of function.

func (*ScalarFunction) GetSingleColumn 

func (sf *ScalarFunction) GetSingleColumn(reverse bool) (*Column, bool)

GetSingleColumn returns (Col, Desc) when the ScalarFunction is equivalent to (Col, Desc) when used as a sort key, otherwise returns (nil, false).

Can only handle: - ast.Plus - ast.Minus - ast.UnaryMinus

func (*ScalarFunction) GetType 

func (sf *ScalarFunction) GetType() *types.FieldType

GetType implements Expression interface.

func (*ScalarFunction) HasCoercibility 

func (sf *ScalarFunction) HasCoercibility() bool

HasCoercibility ...

func (*ScalarFunction) HashCode 

func (sf *ScalarFunction) HashCode(sc *stmtctx.StatementContext) []byte

HashCode implements Expression interface.

func (*ScalarFunction) IsCorrelated 

func (sf *ScalarFunction) IsCorrelated() bool

IsCorrelated implements Expression interface.

func (*ScalarFunction) MarshalJSON 

func (sf *ScalarFunction) MarshalJSON() ([]byte, error)

MarshalJSON implements json.Marshaler interface.

func (*ScalarFunction) ResolveIndices 

func (sf *ScalarFunction) ResolveIndices(schema *Schema) (Expression, error)

ResolveIndices implements Expression interface.

func (*ScalarFunction) ReverseEval 

func (sf *ScalarFunction) ReverseEval(sc *stmtctx.StatementContext, res types.Datum, rType types.RoundingType) (val types.Datum, err error)

ReverseEval evaluates the only one column value with given function result.

func (*ScalarFunction) SetCharsetAndCollation 

func (sf *ScalarFunction) SetCharsetAndCollation(chs, coll string)

SetCharsetAndCollation ...

func (*ScalarFunction) SetCoercibility 

func (sf *ScalarFunction) SetCoercibility(val Coercibility)

SetCoercibility sets a specified coercibility for this expression.

func (*ScalarFunction) String 

func (sf *ScalarFunction) String() string

String implements fmt.Stringer interface.

func (*ScalarFunction) SupportReverseEval 

func (sf *ScalarFunction) SupportReverseEval() bool

SupportReverseEval returns if this expression supports reversed evaluation.

func (*ScalarFunction) VecEvalDecimal 

func (sf *ScalarFunction) VecEvalDecimal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalDecimal evaluates this expression in a vectorized manner.

func (*ScalarFunction) VecEvalDuration 

func (sf *ScalarFunction) VecEvalDuration(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalDuration evaluates this expression in a vectorized manner.

func (*ScalarFunction) VecEvalInt 

func (sf *ScalarFunction) VecEvalInt(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalInt evaluates this expression in a vectorized manner.

func (*ScalarFunction) VecEvalJSON 

func (sf *ScalarFunction) VecEvalJSON(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalJSON evaluates this expression in a vectorized manner.

func (*ScalarFunction) VecEvalReal 

func (sf *ScalarFunction) VecEvalReal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalReal evaluates this expression in a vectorized manner.

func (*ScalarFunction) VecEvalString 

func (sf *ScalarFunction) VecEvalString(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalString evaluates this expression in a vectorized manner.

func (*ScalarFunction) VecEvalTime 

func (sf *ScalarFunction) VecEvalTime(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

VecEvalTime evaluates this expression in a vectorized manner.

func (*ScalarFunction) Vectorized 

func (sf *ScalarFunction) Vectorized() bool

Vectorized returns if this expression supports vectorized evaluation.

type Schema 

type Schema struct {
	Columns []*Column
	Keys    []KeyInfo
	// UniqueKeys stores those unique indexes that allow null values, but Keys does not allow null values.
	// since equivalence conditions can filter out null values, in this case a unique index with null values can be a Key.
	UniqueKeys []KeyInfo
}

Schema stands for the row schema and unique key information get from input.

func MergeSchema 

func MergeSchema(lSchema, rSchema *Schema) *Schema

MergeSchema will merge two schema into one schema. We shouldn't need to consider unique keys. That will be processed in build_key_info.go.

func NewSchema 

func NewSchema(cols ...*Column) *Schema

NewSchema returns a schema made by its parameter.

func (*Schema) Append 

func (s *Schema) Append(col ...*Column)

Append append new column to the columns stored in schema.

func (*Schema) Clone 

func (s *Schema) Clone() *Schema

Clone copies the total schema.

func (*Schema) ColumnIndex 

func (s *Schema) ColumnIndex(col *Column) int

ColumnIndex finds the index for a column.

func (*Schema) ColumnsByIndices 

func (s *Schema) ColumnsByIndices(offsets []int) []*Column

ColumnsByIndices returns columns by multiple offsets. Callers should guarantee that all the offsets provided should be valid, which means offset should: 1. not smaller than 0, and 2. not exceed len(s.Columns)

func (*Schema) ColumnsIndices 

func (s *Schema) ColumnsIndices(cols []*Column) (ret []int)

ColumnsIndices will return a slice which contains the position of each column in schema. If there is one column that doesn't match, nil will be returned.

func (*Schema) Contains 

func (s *Schema) Contains(col *Column) bool

Contains checks if the schema contains the column.

func (*Schema) ExtractColGroups 

func (s *Schema) ExtractColGroups(colGroups [][]*Column) ([][]int, []int)

ExtractColGroups checks if column groups are from current schema, and returns offsets of those satisfied column groups.

func (*Schema) IsUnique 

func (s *Schema) IsUnique(col *Column) bool

IsUnique checks if this column is a unique key which may contain duplicate nulls .

func (*Schema) IsUniqueKey 

func (s *Schema) IsUniqueKey(col *Column) bool

IsUniqueKey checks if this column is a unique key.

func (*Schema) Len 

func (s *Schema) Len() int

Len returns the number of columns in schema.

func (*Schema) RetrieveColumn 

func (s *Schema) RetrieveColumn(col *Column) *Column

RetrieveColumn retrieves column in expression from the columns in schema.

func (*Schema) SetUniqueKeys 

func (s *Schema) SetUniqueKeys(keys []KeyInfo)

SetUniqueKeys will set the value of Schema.Keys.

func (*Schema) String 

func (s *Schema) String() string

String implements fmt.Stringer interface.

type VarAssignment 

type VarAssignment struct {
	Name        string
	Expr        Expression
	IsDefault   bool
	IsGlobal    bool
	IsSystem    bool
	ExtendValue *Constant
}

VarAssignment represents a variable assignment in Set, such as set global a = 1.

type VecExpr 

type VecExpr interface {
	// Vectorized returns if this expression supports vectorized evaluation.
	Vectorized() bool

	// VecEvalInt evaluates this expression in a vectorized manner.
	VecEvalInt(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

	// VecEvalReal evaluates this expression in a vectorized manner.
	VecEvalReal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

	// VecEvalString evaluates this expression in a vectorized manner.
	VecEvalString(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

	// VecEvalDecimal evaluates this expression in a vectorized manner.
	VecEvalDecimal(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

	// VecEvalTime evaluates this expression in a vectorized manner.
	VecEvalTime(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

	// VecEvalDuration evaluates this expression in a vectorized manner.
	VecEvalDuration(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error

	// VecEvalJSON evaluates this expression in a vectorized manner.
	VecEvalJSON(ctx sessionctx.Context, input *chunk.Chunk, result *chunk.Column) error
}

VecExpr contains all vectorized evaluation methods.

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