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Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
Types ¶
type AggregationFunction ¶
type AggregationFunction interface {
// Update during executing.
Update(row []types.Datum, groupKey []byte, ctx context.Context) error
// GetGroupResult will be called when all data have been processed.
GetGroupResult(groupKey []byte) types.Datum
// GetArgs stands for getting all arguments.
GetArgs() []Expression
// GetName gets the aggregation function name.
GetName() string
// SetArgs set argument by index.
SetArgs(idx int, expr Expression)
// Clear collects the mapper's memory.
Clear()
}
AggregationFunction stands for aggregate functions.
func NewAggFunction ¶
func NewAggFunction(funcType string, funcArgs []Expression, distinct bool) AggregationFunction
NewAggFunction creates a new AggregationFunction.
type Column ¶
type Column struct {
FromID string
ColName model.CIStr
DBName model.CIStr
TblName model.CIStr
RetType *types.FieldType
// Position means the position of this column that appears in the select fields.
// e.g. SELECT name as id , 1 - id as id , 1 + name as id, name as id from src having id = 1;
// There are four ids in the same schema, so you can't identify the column through the FromID and ColName.
Position int
// IsAggOrSubq means if this column is referenced to a Aggregation column or a Subquery column.
// If so, this column's name will be the plain sql text.
IsAggOrSubq bool
// only used during execution
Index int
// contains filtered or unexported fields
}
Column represents a column.
func (*Column) DeepCopy ¶
func (col *Column) DeepCopy() Expression
DeepCopy implements Expression interface.
func (*Column) Equal ¶
func (col *Column) Equal(expr Expression) bool
Equal checks if two columns are equal
type Constant ¶
Constant stands for a constant value.
func (*Constant) DeepCopy ¶
func (c *Constant) DeepCopy() Expression
DeepCopy implements Expression interface.
type Expression ¶
type Expression interface {
// Eval evaluates an expression through a row.
Eval(row []types.Datum, ctx context.Context) (types.Datum, error)
// Get the expression return type.
GetType() *types.FieldType
// DeepCopy copies an expression totally.
DeepCopy() Expression
// ToString converts an expression into a string.
ToString() string
}
Expression represents all scalar expression in SQL.
func ComposeCNFCondition ¶
func ComposeCNFCondition(conditions []Expression) Expression
ComposeCNFCondition composes CNF items into a balance deep CNF tree, which benefits a lot for pb decoder/encoder.
func ScalarFuncs2Exprs ¶
func ScalarFuncs2Exprs(funcs []*ScalarFunction) []Expression
ScalarFuncs2Exprs converts []*ScalarFunction to []Expression.
func Schema2Exprs ¶
func Schema2Exprs(schema Schema) []Expression
Schema2Exprs converts []*Column to []Expression.
type ScalarFunction ¶
type ScalarFunction struct {
Args []Expression
FuncName model.CIStr
// TODO: Implement type inference here, now we use ast's return type temporarily.
RetType *types.FieldType
Function evaluator.BuiltinFunc
}
ScalarFunction is the function that returns a value.
func NewFunction ¶
func NewFunction(funcName string, retType *types.FieldType, args ...Expression) (*ScalarFunction, error)
NewFunction creates a new scalar function.
func (*ScalarFunction) DeepCopy ¶
func (sf *ScalarFunction) DeepCopy() Expression
DeepCopy implements Expression interface.
func (*ScalarFunction) GetType ¶
func (sf *ScalarFunction) GetType() *types.FieldType
GetType implements Expression interface.
func (*ScalarFunction) ToString ¶
func (sf *ScalarFunction) ToString() string
ToString implements Expression interface.
type Schema ¶
type Schema []*Column
Schema stands for the row schema get from input.
func (Schema) FindColumn ¶
func (s Schema) FindColumn(astCol *ast.ColumnName) (*Column, error)
FindColumn finds an Column from schema for a ast.ColumnName. It compares the db/table/column names. If there are more than one result, it will raise ambiguous error.
func (Schema) InitIndices ¶
func (s Schema) InitIndices()
InitIndices sets indices for columns in schema.
func (Schema) RetrieveColumn ¶
RetrieveColumn retrieves column in expression from the columns in schema.
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