rel

func CartesianProduct ¶

func CartesianProduct(relations ...Relation) Relation

func Join ¶

func Join(relations ...Relation) Relation

Join returns all {x, y, z} such that s has {x, y} and t has {y, z}. x, y and z represent sets of keys:

x: keys unique to maps in s
y: keys common to maps in both
z: keys unique to maps in t

It is assumed that all maps in s have the same keys and likewise for t.

func Nest ¶

func Nest(s Relation, attrAttrs frozen.Map[string, frozen.Set[string]]) Relation

Nest returns a relation with some attributes nested as subrelations.

Example:

input:
   _c_ _a__
  |_1_|_10_|
  |_1_|_11_|
  |_2_|_13_|
  |_3_|_11_|
  |_4_|_14_|
  |_3_|_10_|
  |_4_|_13_|

nest(input, {aa: {a}}):
   _c_ ___aa___
  | 1 |  _a__  |
  |   | |_10_| |
  |___|_|_11_|_|
  | 2 |  _a__  |
  |___|_|_13_|_|
  | 3 |  _a__  |
  |   | |_10_| |
  |___|_|_11_|_|
  | 4 |  _a__  |
  |   | |_13_| |
  |___|_|_14_|_|

func New ¶

func New(header []string, tuples ...[]any) Relation

New returns a new relation.

func Project ¶

func Project(s Relation, attrs ...string) Relation

Project returns a Set with the result of projecting each map.

func Unnest ¶

func Unnest(s Relation, attr string) Relation

Unnest returns a relation with some subrelations unnested. This is the reverse of Nest.

func NewTuple ¶

func NewTuple(kvs ...frozen.KeyValue[string, any]) Tuple