agnostic

package
v0.1.4 Latest Latest
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 Go to latest Published: Jul 24, 2024 License: BSD-3-Clause Imports: 14 Imported by: 0

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Index

Constants

View Source 
const (
	DefaultSchema = "public"
)

Variables

View Source 
var (
	NotImplemented = errors.New("not implemented")
)

Functions

func PrintQueryPlan 

func PrintQueryPlan(n Node, depth int, printer func(fmt string, varargs ...any))

PrintQueryPlan

func ToInstance 

func ToInstance(value, typeName string) (any, error)

func WithAlias 

func WithAlias(alias string) func(*AttributeSelector)

Types

type AndPredicate 

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

func NewAndPredicate 

func NewAndPredicate(left, right Predicate) *AndPredicate

func (*AndPredicate) Attribute 

func (p *AndPredicate) Attribute() []string

func (*AndPredicate) Eval 

func (p *AndPredicate) Eval(cols []string, t *Tuple) (bool, error)

func (*AndPredicate) Left 

func (p *AndPredicate) Left() (Predicate, bool)

func (*AndPredicate) Relation 

func (p *AndPredicate) Relation() string

func (*AndPredicate) Right 

func (p *AndPredicate) Right() (Predicate, bool)

func (AndPredicate) String 

func (p AndPredicate) String() string

func (*AndPredicate) Type 

func (p *AndPredicate) Type() PredicateType

type Attribute 

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

Attribute is a named column of a relation AKA Field AKA Column

func NewAttribute 

func NewAttribute(name, typeName string) Attribute

func (Attribute) HasAutoIncrement 

func (a Attribute) HasAutoIncrement() bool

func (Attribute) Name 

func (a Attribute) Name() string

func (Attribute) String 

func (a Attribute) String() string

func (Attribute) WithAutoIncrement 

func (a Attribute) WithAutoIncrement() Attribute

func (Attribute) WithDefault 

func (a Attribute) WithDefault(defaultValue Defaulter) Attribute

func (Attribute) WithDefaultConst 

func (a Attribute) WithDefaultConst(defaultValue any) Attribute

func (Attribute) WithDefaultNow 

func (a Attribute) WithDefaultNow() Attribute

func (Attribute) WithUnique 

func (a Attribute) WithUnique() Attribute

type AttributeSelector 

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

func NewAttributeSelector 

func NewAttributeSelector(rel string, attrs []string, functors ...func(*AttributeSelector)) *AttributeSelector

func (*AttributeSelector) Alias 

func (s *AttributeSelector) Alias() string

func (*AttributeSelector) Attribute 

func (s *AttributeSelector) Attribute() []string

func (*AttributeSelector) Relation 

func (s *AttributeSelector) Relation() string

func (*AttributeSelector) Select 

func (s *AttributeSelector) Select(cols []string, in []*list.Element) (out []*Tuple, err error)

func (AttributeSelector) String 

func (s AttributeSelector) String() string

type AttributeValueFunctor 

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

func (*AttributeValueFunctor) Attribute 

func (f *AttributeValueFunctor) Attribute() []string

func (*AttributeValueFunctor) Relation 

func (f *AttributeValueFunctor) Relation() string

func (AttributeValueFunctor) String 

func (f AttributeValueFunctor) String() string

func (*AttributeValueFunctor) Value 

func (f *AttributeValueFunctor) Value(cols []string, t *Tuple) any

type AvgSelector 

type AvgSelector struct {
}

type ConstValueFunctor 

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

func (*ConstValueFunctor) Attribute 

func (f *ConstValueFunctor) Attribute() []string

func (*ConstValueFunctor) Relation 

func (f *ConstValueFunctor) Relation() string

func (ConstValueFunctor) String 

func (f ConstValueFunctor) String() string

func (*ConstValueFunctor) Value 

func (f *ConstValueFunctor) Value([]string, *Tuple) any

type CountSelector 

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

func NewCountSelector 

func NewCountSelector(rname string, attr string) *CountSelector

func (*CountSelector) Alias 

func (s *CountSelector) Alias() string

func (*CountSelector) Attribute 

func (s *CountSelector) Attribute() []string

func (*CountSelector) Relation 

func (s *CountSelector) Relation() string

func (*CountSelector) Select 

func (s *CountSelector) Select(cols []string, in []*list.Element) (out []*Tuple, err error)

type Defaulter 

type Defaulter func() any

func NewRandString 

func NewRandString(n int) Defaulter

type Deleter 

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

func NewDeleterNode 

func NewDeleterNode(relation *Relation, changes *list.List) *Deleter

func (*Deleter) Attribute 

func (u *Deleter) Attribute() []string

func (*Deleter) Children 

func (u *Deleter) Children() []Node

func (*Deleter) EstimateCardinal 

func (u *Deleter) EstimateCardinal() int64

func (*Deleter) Exec 

func (u *Deleter) Exec() (cols []string, out []*list.Element, err error)

func (*Deleter) Relation 

func (u *Deleter) Relation() string

func (Deleter) String 

func (u Deleter) String() string

type DistinctSorter 

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

func NewDistinctSorter 

func NewDistinctSorter(rel string, attrs []string) *DistinctSorter

func (*DistinctSorter) Children 

func (d *DistinctSorter) Children() []Node

func (*DistinctSorter) EstimateCardinal 

func (d *DistinctSorter) EstimateCardinal() int64

func (*DistinctSorter) Exec 

func (d *DistinctSorter) Exec() ([]string, []*list.Element, error)

func (*DistinctSorter) Priority 

func (d *DistinctSorter) Priority() int

func (*DistinctSorter) SetNode 

func (d *DistinctSorter) SetNode(n Node)

func (DistinctSorter) String 

func (s DistinctSorter) String() string

type Domain 

type Domain struct {
}

Domain is the set of allowable values for an Attribute.

type Engine 

type Engine struct {
	sync.Mutex
	// contains filtered or unexported fields
}

func NewEngine 

func NewEngine() *Engine

func (*Engine) Begin 

func (e *Engine) Begin() (*Transaction, error)

type EqPredicate 

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

func NewEqPredicate 

func NewEqPredicate(left, right ValueFunctor) *EqPredicate

func (*EqPredicate) Attribute 

func (p *EqPredicate) Attribute() []string

func (*EqPredicate) Eval 

func (p *EqPredicate) Eval(cols []string, t *Tuple) (bool, error)

func (*EqPredicate) Left 

func (p *EqPredicate) Left() (Predicate, bool)

func (*EqPredicate) Relation 

func (p *EqPredicate) Relation() string

func (*EqPredicate) Right 

func (p *EqPredicate) Right() (Predicate, bool)

func (EqPredicate) String 

func (p EqPredicate) String() string

func (*EqPredicate) Type 

func (p *EqPredicate) Type() PredicateType

type FalsePredicate 

type FalsePredicate struct {
}

func NewFalsePredicate 

func NewFalsePredicate() *FalsePredicate

func (*FalsePredicate) Attribute 

func (p *FalsePredicate) Attribute() []string

func (*FalsePredicate) Eval 

func (p *FalsePredicate) Eval([]string, *Tuple) (bool, error)

func (*FalsePredicate) Left 

func (p *FalsePredicate) Left() (Predicate, bool)

func (*FalsePredicate) Relation 

func (p *FalsePredicate) Relation() string

func (*FalsePredicate) Right 

func (p *FalsePredicate) Right() (Predicate, bool)

func (FalsePredicate) String 

func (p FalsePredicate) String() string

func (*FalsePredicate) Type 

func (p *FalsePredicate) Type() PredicateType

type ForeignKey 

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

type GePredicate 

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

func NewGePredicate 

func NewGePredicate(left, right ValueFunctor) *GePredicate

func (*GePredicate) Attribute 

func (p *GePredicate) Attribute() []string

func (*GePredicate) Eval 

func (p *GePredicate) Eval(cols []string, t *Tuple) (bool, error)

func (*GePredicate) Left 

func (p *GePredicate) Left() (Predicate, bool)

func (*GePredicate) Relation 

func (p *GePredicate) Relation() string

func (*GePredicate) Right 

func (p *GePredicate) Right() (Predicate, bool)

func (GePredicate) String 

func (p GePredicate) String() string

func (*GePredicate) Type 

func (p *GePredicate) Type() PredicateType

type GeqPredicate 

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

func NewGeqPredicate 

func NewGeqPredicate(left, right ValueFunctor) *GeqPredicate

func (*GeqPredicate) Attribute 

func (p *GeqPredicate) Attribute() []string

func (*GeqPredicate) Eval 

func (p *GeqPredicate) Eval(cols []string, t *Tuple) (bool, error)

func (*GeqPredicate) Left 

func (p *GeqPredicate) Left() (Predicate, bool)

func (*GeqPredicate) Relation 

func (p *GeqPredicate) Relation() string

func (*GeqPredicate) Right 

func (p *GeqPredicate) Right() (Predicate, bool)

func (GeqPredicate) String 

func (p GeqPredicate) String() string

func (*GeqPredicate) Type 

func (p *GeqPredicate) Type() PredicateType

type GroupBySorter 

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

func NewGroupBySorter 

func NewGroupBySorter(rel string, attrs []string) *GroupBySorter

func (*GroupBySorter) Children 

func (s *GroupBySorter) Children() []Node

func (*GroupBySorter) EstimateCardinal 

func (s *GroupBySorter) EstimateCardinal() int64

func (*GroupBySorter) Exec 

func (s *GroupBySorter) Exec() ([]string, []*list.Element, error)

func (*GroupBySorter) Priority 

func (s *GroupBySorter) Priority() int

func (*GroupBySorter) SetNode 

func (s *GroupBySorter) SetNode(n Node)

func (*GroupBySorter) SetSelector 

func (s *GroupBySorter) SetSelector(n Node)

func (GroupBySorter) String 

func (s GroupBySorter) String() string

type HashIndex 

type HashIndex struct {
	maphash.Hash
	// contains filtered or unexported fields
}

func NewHashIndex 

func NewHashIndex(name string, relName string, relAttrs []Attribute, attrsName []string, attrs []int) *HashIndex

func (*HashIndex) Add 

func (h *HashIndex) Add(e *list.Element)

func (*HashIndex) CanSourceWith 

func (h *HashIndex) CanSourceWith(p Predicate) (bool, int64)

func (*HashIndex) Get 

func (h *HashIndex) Get(values []any) (*list.Element, error)

func (*HashIndex) Name 

func (h *HashIndex) Name() string

func (*HashIndex) Remove 

func (h *HashIndex) Remove(e *list.Element)

func (*HashIndex) String 

func (h *HashIndex) String() string

func (*HashIndex) Truncate 

func (h *HashIndex) Truncate()

type InPredicate 

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

func NewInPredicate 

func NewInPredicate(v ValueFunctor, src Node) *InPredicate

func (*InPredicate) Attribute 

func (p *InPredicate) Attribute() []string

func (*InPredicate) Eval 

func (p *InPredicate) Eval(inCols []string, in *Tuple) (bool, error)

func (*InPredicate) Left 

func (p *InPredicate) Left() (Predicate, bool)

func (*InPredicate) Relation 

func (p *InPredicate) Relation() string

func (*InPredicate) Right 

func (p *InPredicate) Right() (Predicate, bool)

func (InPredicate) String 

func (p InPredicate) String() string

func (*InPredicate) Type 

func (p *InPredicate) Type() PredicateType

type Index 

type Index interface {
	Truncate()
	Add(*list.Element)
	Remove(*list.Element)
	Name() string
	CanSourceWith(p Predicate) (bool, int64)
	Get(values []any) (*list.Element, error)
}

type IndexSrc 

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

func NewHashIndexSource 

func NewHashIndexSource(index Index, alias string, p Predicate) (*IndexSrc, error)

func (*IndexSrc) Columns 

func (s *IndexSrc) Columns() []string

func (*IndexSrc) EstimateCardinal 

func (s *IndexSrc) EstimateCardinal() int64

func (*IndexSrc) HasNext 

func (s *IndexSrc) HasNext() bool

func (*IndexSrc) Next 

func (s *IndexSrc) Next() *list.Element

func (IndexSrc) String 

func (s IndexSrc) String() string

type IndexType 

type IndexType int
const (
	HashIndexType IndexType = iota
	BTreeIndexType
)

type Joiner 

type Joiner interface {
	Node
	Left() string
	SetLeft(n Node)
	Right() string
	SetRight(n Node)
}

Joiner joins two relation together.

Should be able to estimate cardinality of join for cost optimization.

Possible implementations:

  • NaturalJoiner
  • LeftOuterJoiner
  • RightOuterJoiner
  • FullOuterJoiner

type Joiners 

type Joiners []Joiner

func (Joiners) Len 

func (js Joiners) Len() int

func (Joiners) Less 

func (js Joiners) Less(i, j int) bool

func (Joiners) Swap 

func (js Joiners) Swap(i, j int)

type LePredicate 

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

func NewLePredicate 

func NewLePredicate(left, right ValueFunctor) *LePredicate

func (*LePredicate) Attribute 

func (p *LePredicate) Attribute() []string

func (*LePredicate) Eval 

func (p *LePredicate) Eval(cols []string, t *Tuple) (bool, error)

func (*LePredicate) Left 

func (p *LePredicate) Left() (Predicate, bool)

func (*LePredicate) Relation 

func (p *LePredicate) Relation() string

func (*LePredicate) Right 

func (p *LePredicate) Right() (Predicate, bool)

func (LePredicate) String 

func (p LePredicate) String() string

func (*LePredicate) Type 

func (p *LePredicate) Type() PredicateType

type LeqPredicate 

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

func NewLeqPredicate 

func NewLeqPredicate(left, right ValueFunctor) *LeqPredicate

func (*LeqPredicate) Attribute 

func (p *LeqPredicate) Attribute() []string

func (*LeqPredicate) Eval 

func (p *LeqPredicate) Eval(cols []string, t *Tuple) (bool, error)

func (*LeqPredicate) Left 

func (p *LeqPredicate) Left() (Predicate, bool)

func (*LeqPredicate) Relation 

func (p *LeqPredicate) Relation() string

func (*LeqPredicate) Right 

func (p *LeqPredicate) Right() (Predicate, bool)

func (LeqPredicate) String 

func (p LeqPredicate) String() string

func (*LeqPredicate) Type 

func (p *LeqPredicate) Type() PredicateType

type LimitSorter 

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

func NewLimitSorter 

func NewLimitSorter(limit int64) *LimitSorter

func (*LimitSorter) Children 

func (d *LimitSorter) Children() []Node

func (*LimitSorter) EstimateCardinal 

func (d *LimitSorter) EstimateCardinal() int64

func (*LimitSorter) Exec 

func (d *LimitSorter) Exec() ([]string, []*list.Element, error)

func (*LimitSorter) Priority 

func (d *LimitSorter) Priority() int

func (*LimitSorter) SetNode 

func (d *LimitSorter) SetNode(n Node)

func (LimitSorter) String 

func (s LimitSorter) String() string

type ListNode 

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

func NewListNode 

func NewListNode(values ...any) *ListNode

func (*ListNode) Children 

func (ln *ListNode) Children() []Node

func (*ListNode) EstimateCardinal 

func (ln *ListNode) EstimateCardinal() int64

func (*ListNode) Exec 

func (ln *ListNode) Exec() ([]string, []*list.Element, error)

func (ListNode) String 

func (ln ListNode) String() string

type MaxSelector 

type MaxSelector struct {
}

type NaturalJoin 

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

func NewNaturalJoin 

func NewNaturalJoin(leftRel, leftAttr, rightRel, rightAttr string) *NaturalJoin

func (*NaturalJoin) Children 

func (j *NaturalJoin) Children() []Node

func (*NaturalJoin) EstimateCardinal 

func (j *NaturalJoin) EstimateCardinal() int64

func (*NaturalJoin) Exec 

func (j *NaturalJoin) Exec() ([]string, []*list.Element, error)

func (*NaturalJoin) Left 

func (j *NaturalJoin) Left() string

func (*NaturalJoin) Right 

func (j *NaturalJoin) Right() string

func (*NaturalJoin) SetLeft 

func (j *NaturalJoin) SetLeft(n Node)

func (*NaturalJoin) SetRight 

func (j *NaturalJoin) SetRight(n Node)

func (NaturalJoin) String 

func (j NaturalJoin) String() string

type NeqPredicate 

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

func NewNeqPredicate 

func NewNeqPredicate(left, right ValueFunctor) *NeqPredicate

func (*NeqPredicate) Attribute 

func (p *NeqPredicate) Attribute() []string

func (*NeqPredicate) Eval 

func (p *NeqPredicate) Eval(cols []string, t *Tuple) (bool, error)

func (*NeqPredicate) Left 

func (p *NeqPredicate) Left() (Predicate, bool)

func (*NeqPredicate) Relation 

func (p *NeqPredicate) Relation() string

func (*NeqPredicate) Right 

func (p *NeqPredicate) Right() (Predicate, bool)

func (NeqPredicate) String 

func (p NeqPredicate) String() string

func (*NeqPredicate) Type 

func (p *NeqPredicate) Type() PredicateType

type Node 

type Node interface {
	Exec() ([]string, []*list.Element, error)
	EstimateCardinal() int64
	Children() []Node
}

Node is an element of a quey plan

Joiner, Sorter and Scanner implement Node.

type NotPredicate 

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

func NewNotPredicate 

func NewNotPredicate(src Predicate) *NotPredicate

func (*NotPredicate) Attribute 

func (p *NotPredicate) Attribute() []string

func (*NotPredicate) Eval 

func (p *NotPredicate) Eval(cols []string, t *Tuple) (bool, error)

func (*NotPredicate) Left 

func (p *NotPredicate) Left() (Predicate, bool)

func (*NotPredicate) Relation 

func (p *NotPredicate) Relation() string

func (*NotPredicate) Right 

func (p *NotPredicate) Right() (Predicate, bool)

func (NotPredicate) String 

func (p NotPredicate) String() string

func (*NotPredicate) Type 

func (p *NotPredicate) Type() PredicateType

type NowValueFunctor 

type NowValueFunctor struct {
}

func (*NowValueFunctor) Attribute 

func (f *NowValueFunctor) Attribute() []string

func (*NowValueFunctor) Relation 

func (f *NowValueFunctor) Relation() string

func (NowValueFunctor) String 

func (f NowValueFunctor) String() string

func (*NowValueFunctor) Value 

func (f *NowValueFunctor) Value([]string, *Tuple) any

type OffsetSorter 

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

func NewOffsetSorter 

func NewOffsetSorter(o int) *OffsetSorter

func (*OffsetSorter) Children 

func (s *OffsetSorter) Children() []Node

func (*OffsetSorter) EstimateCardinal 

func (s *OffsetSorter) EstimateCardinal() int64

func (*OffsetSorter) Exec 

func (s *OffsetSorter) Exec() ([]string, []*list.Element, error)

func (*OffsetSorter) Priority 

func (s *OffsetSorter) Priority() int

func (*OffsetSorter) SetNode 

func (s *OffsetSorter) SetNode(n Node)

func (OffsetSorter) String 

func (s OffsetSorter) String() string

type OrPredicate 

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

func NewOrPredicate 

func NewOrPredicate(left, right Predicate) *OrPredicate

func (*OrPredicate) Attribute 

func (p *OrPredicate) Attribute() []string

func (*OrPredicate) Eval 

func (p *OrPredicate) Eval(cols []string, t *Tuple) (bool, error)

func (*OrPredicate) Left 

func (p *OrPredicate) Left() (Predicate, bool)

func (*OrPredicate) Relation 

func (p *OrPredicate) Relation() string

func (*OrPredicate) Right 

func (p *OrPredicate) Right() (Predicate, bool)

func (OrPredicate) String 

func (p OrPredicate) String() string

func (*OrPredicate) Type 

func (p *OrPredicate) Type() PredicateType

type OrderBySorter 

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

func NewOrderBySorter 

func NewOrderBySorter(rel string, attrs []SortExpression) *OrderBySorter

func (*OrderBySorter) Children 

func (s *OrderBySorter) Children() []Node

func (*OrderBySorter) EstimateCardinal 

func (s *OrderBySorter) EstimateCardinal() int64

func (*OrderBySorter) Exec 

func (s *OrderBySorter) Exec() ([]string, []*list.Element, error)

func (*OrderBySorter) Priority 

func (s *OrderBySorter) Priority() int

func (*OrderBySorter) SetNode 

func (s *OrderBySorter) SetNode(n Node)

func (OrderBySorter) String 

func (s OrderBySorter) String() string

type Picker 

type Picker interface {
	Relation() string
	Attribute() []string
}

Picker interface is used by query planner to define which relations and attributes are used in a query.

Can be empty.

Selector and Predicate implement Picker.

type Predicate 

type Predicate interface {
	Picker
	Type() PredicateType
	Left() (Predicate, bool)
	Right() (Predicate, bool)
	Eval([]string, *Tuple) (bool, error)
}

Predicate defines filter to be applied on spcified relation row

func NewComparisonPredicate 

func NewComparisonPredicate(left ValueFunctor, t PredicateType, right ValueFunctor) (Predicate, error)

type PredicateType 

type PredicateType int
const (
	And PredicateType = iota
	Or
	Eq
	Geq
	Leq
	Le
	Ge
	Neq
	Like
	In
	Not
	True
	False
)

type Relation 

type Relation struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

func NewRelation 

func NewRelation(schema, name string, attributes []Attribute, pk []string) (*Relation, error)

func (*Relation) Attribute 

func (r *Relation) Attribute(name string) (int, Attribute, error)

func (*Relation) CheckPrimaryKey added in v0.1.3 

func (r *Relation) CheckPrimaryKey(tuple *Tuple) (bool, error)

func (*Relation) String 

func (r *Relation) String() string

func (*Relation) Truncate 

func (r *Relation) Truncate() int64

type RelationChange 

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

type RelationScanner 

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

func NewRelationScanner 

func NewRelationScanner(src Source, predicates []Predicate) *RelationScanner

func (*RelationScanner) Append 

func (s *RelationScanner) Append(p Predicate)

func (*RelationScanner) Children 

func (s *RelationScanner) Children() []Node

func (*RelationScanner) EstimateCardinal 

func (s *RelationScanner) EstimateCardinal() int64

No idea on how to estimate cardinal of scanner given predicates

min: 0 max: len(src) avg: len(src)/2

func (*RelationScanner) Exec 

func (s *RelationScanner) Exec() ([]string, []*list.Element, error)

func (RelationScanner) String 

func (s RelationScanner) String() string

type Scanner 

type Scanner interface {
	Node
	Append(Predicate)
}

Scanner produce results by scanning the relation.

The query plan initialize a Scanner for each relation with: * The best source possible regarding cost (Hashmap, Btree, SeqScan) * A (possibly) recursive predicate to filter on

type Schema 

type Schema struct {
	sync.RWMutex
	// contains filtered or unexported fields
}

func NewSchema 

func NewSchema(name string) *Schema

func (*Schema) Add 

func (s *Schema) Add(name string, r *Relation)

func (*Schema) Relation 

func (s *Schema) Relation(name string) (*Relation, error)

func (*Schema) Remove 

func (s *Schema) Remove(name string) (*Relation, error)

type SchemaChange 

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

type Selector 

type Selector interface {
	Picker
	Alias() string
	Select([]string, []*list.Element) ([]*Tuple, error)
}

Selector defines values to be returned to user

Possible Selector implementations:

  • Attribute
  • Star
  • Max
  • Min
  • Avg
  • ...

type SelectorNode 

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

func NewSelectorNode 

func NewSelectorNode(selectors []Selector, n Node) *SelectorNode

func (*SelectorNode) Children 

func (sn *SelectorNode) Children() []Node

func (*SelectorNode) Columns 

func (sn *SelectorNode) Columns() []string

func (*SelectorNode) EstimateCardinal 

func (sn *SelectorNode) EstimateCardinal() int64

func (*SelectorNode) Exec 

func (sn *SelectorNode) Exec() ([]string, []*list.Element, error)

func (SelectorNode) String 

func (sn SelectorNode) String() string

type SeqScanSrc 

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

func NewSeqScan 

func NewSeqScan(r *Relation, alias string) *SeqScanSrc

func (*SeqScanSrc) Columns 

func (s *SeqScanSrc) Columns() []string

func (*SeqScanSrc) EstimateCardinal 

func (s *SeqScanSrc) EstimateCardinal() int64

func (*SeqScanSrc) HasNext 

func (s *SeqScanSrc) HasNext() bool

func (*SeqScanSrc) Next 

func (s *SeqScanSrc) Next() *list.Element

func (SeqScanSrc) String 

func (s SeqScanSrc) String() string

type SortExpression 

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

func NewSortExpression 

func NewSortExpression(attr string, direction SortType) SortExpression

type SortType 

type SortType int
const (
	ASC SortType = iota
	DESC
)

type Sorter 

type Sorter interface {
	Node
	Priority() int
	SetNode(Node)
}

Sorter produce a sorted result from single child node

GroupBy (-10000) before Having (-5000) before Order (0) before Distinct (1000) before Offset (5000) before Limit (10000).

GroupBy must contains both selector node and last join to compute arithmetic on all groups

Possible implementations:

  • OrderAscSort
  • OrderDescSort
  • HavingSort
  • DistinctSort
  • Limit
  • Offset

type Sorters 

type Sorters []Sorter

Sorters sort the sorters \o/

Why ? I don't want to put on package caller the responsability to order them correctly. It's up to the query planner.

func (Sorters) Len 

func (js Sorters) Len() int

func (Sorters) Less 

func (js Sorters) Less(i, j int) bool

func (Sorters) Swap 

func (js Sorters) Swap(i, j int)

type Source 

type Source interface {
	HasNext() bool
	Next() *list.Element
	EstimateCardinal() int64
	Columns() []string
}

type StarSelector 

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

func NewStarSelector 

func NewStarSelector(rname string) *StarSelector

func (*StarSelector) Alias 

func (s *StarSelector) Alias() string

func (*StarSelector) Attribute 

func (s *StarSelector) Attribute() []string

func (*StarSelector) Relation 

func (s *StarSelector) Relation() string

func (*StarSelector) Select 

func (s *StarSelector) Select(cols []string, in []*list.Element) (out []*Tuple, err error)

func (StarSelector) String 

func (s StarSelector) String() string

type SubqueryNode 

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

func NewSubqueryNode 

func NewSubqueryNode(src Node) *SubqueryNode

func (*SubqueryNode) Children 

func (sn *SubqueryNode) Children() []Node

func (*SubqueryNode) EstimateCardinal 

func (sn *SubqueryNode) EstimateCardinal() int64

func (*SubqueryNode) Exec 

func (sn *SubqueryNode) Exec() ([]string, []*list.Element, error)

func (SubqueryNode) String 

func (sn SubqueryNode) String() string

type Transaction 

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

func NewTransaction 

func NewTransaction(e *Engine) (*Transaction, error)

func (*Transaction) CheckRelation 

func (t *Transaction) CheckRelation(schemaName, relName string) bool

func (*Transaction) CheckSchema 

func (t *Transaction) CheckSchema(schemaName string) bool

func (*Transaction) Commit 

func (t *Transaction) Commit() (int, error)

func (*Transaction) CreateIndex 

func (t *Transaction) CreateIndex(schema, relation, index string, it IndexType, attrs []string) error

func (*Transaction) CreateRelation 

func (t *Transaction) CreateRelation(schemaName, relName string, attributes []Attribute, pk []string) error

func (*Transaction) CreateSchema 

func (t *Transaction) CreateSchema(schemaName string) error

func (*Transaction) Delete 

func (t *Transaction) Delete(schema, relation string, selectors []Selector, p Predicate) ([]string, []*Tuple, error)

Delete rows from relation.

Delete node needs to be inserted right as child of selector node.

func (*Transaction) DropRelation 

func (t *Transaction) DropRelation(schemaName, relName string) error

func (*Transaction) DropSchema 

func (t *Transaction) DropSchema(schemaName string) error

func (Transaction) Error 

func (t Transaction) Error() error

func (*Transaction) Insert 

func (t *Transaction) Insert(schema, relation string, values map[string]any) (*Tuple, error)

Build tuple for given relation for each column: - if not specified, use default value if set - if specified:

  • check domain
  • check unique
  • check foreign key

If tuple is valid, then - check primary key - insert into rows list - update index if any

func (*Transaction) Plan 

func (t *Transaction) Plan(schema string, selectors []Selector, p Predicate, joiners []Joiner, sorters []Sorter) (Node, error)

func (*Transaction) Query 

func (t *Transaction) Query(schema string, selectors []Selector, p Predicate, joiners []Joiner, sorters []Sorter) ([]string, []*Tuple, error)

Query data from relations

cf: https://en.wikipedia.org/wiki/Query_optimization

cf: https://en.wikipedia.org/wiki/Relational_algebra

* (1) Transaction safety : list all touched relations and lock them * (2) Sourcing : evaluate which indexes query can use for each relation. HashIndex > Btree > SeqScan * (3) Join ordering : estimate the cardinality (Join selection factor) of each relation after predicates filtering, then order the join by lower cardinality * (4) Selection : build filtered relations on each leaf (parallelisation possible) * (5) Join : join filtered relations on each node recursively * (6) Return result : return result to user with selectors

TODO: foreign keys should have hashmap index

func (*Transaction) RelationAttribute 

func (t *Transaction) RelationAttribute(schName, relName, attrName string) (int, Attribute, error)

func (*Transaction) Rollback 

func (t *Transaction) Rollback()

func (*Transaction) Truncate 

func (t *Transaction) Truncate(schema, relation string) (int64, error)

func (*Transaction) Update 

func (t *Transaction) Update(schema, relation string, values map[string]any, selectors []Selector, p Predicate) ([]string, []*Tuple, error)

Update relation with given values.

Update node needs to be inserted right as child of selector node.

type TruePredicate 

type TruePredicate struct {
}

func NewTruePredicate 

func NewTruePredicate() *TruePredicate

func (*TruePredicate) Attribute 

func (p *TruePredicate) Attribute() []string

func (*TruePredicate) Eval 

func (p *TruePredicate) Eval([]string, *Tuple) (bool, error)

func (*TruePredicate) Left 

func (p *TruePredicate) Left() (Predicate, bool)

func (*TruePredicate) Relation 

func (p *TruePredicate) Relation() string

func (*TruePredicate) Right 

func (p *TruePredicate) Right() (Predicate, bool)

func (TruePredicate) String 

func (p TruePredicate) String() string

func (*TruePredicate) Type 

func (p *TruePredicate) Type() PredicateType

type Tuple 

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

Tuple is a row in a relation

func NewTuple 

func NewTuple(values ...any) *Tuple

NewTuple should check that value are for the right Attribute and match domain

func (*Tuple) Append 

func (t *Tuple) Append(values ...any)

Append add a value to the tuple

func (*Tuple) Values 

func (t *Tuple) Values() []any

type Updater 

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

func NewUpdaterNode 

func NewUpdaterNode(relation *Relation, changes *list.List, values map[string]any) *Updater

func (*Updater) Attribute 

func (u *Updater) Attribute() []string

func (*Updater) Children 

func (u *Updater) Children() []Node

func (*Updater) EstimateCardinal 

func (u *Updater) EstimateCardinal() int64

func (*Updater) Exec 

func (u *Updater) Exec() (cols []string, out []*list.Element, err error)

func (*Updater) Relation 

func (u *Updater) Relation() string

func (Updater) String 

func (u Updater) String() string

type ValueChange 

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

type ValueFunctor 

type ValueFunctor interface {
	Picker
	Value(columns []string, tuple *Tuple) any
}

ValueFunctor is used by Predicate to compare values

Possible ValueFunctor implementation:

  • ConstValueFunctor
  • AttributeValueFunctor
  • NowValueFunctor

func NewAttributeValueFunctor 

func NewAttributeValueFunctor(rname, aname string) ValueFunctor

NewAttributeValueFunctor creates a ValueFunctor returning attribute value in given tuple

func NewConstValueFunctor 

func NewConstValueFunctor(v any) ValueFunctor

NewConstValueFunctor creates a ValueFunctor returning v

func NewNowValueFunctor 

func NewNowValueFunctor() ValueFunctor

NewNowValueFunctor creates a ValueFunctor returning time.Now()

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