stupidb.core

StupiDB. The stupidest database you’ll ever come across.

This is project designed to illustate the concepts that underly a typical relational database implementation, starting at naive execution of table-stakes features up to rule-based query optimization.

Warning

Please do not use this for any other reason than learning. There are no guarantees here except that there will be bugs.

Classes

Aggregation(child, metrics)	A relation representing aggregation of columns.
CrossJoin(left, right)
Difference(left, right)	Unique difference between two relations.
DifferenceAll(left, right)	Non-unique difference between two relations.
GroupBy(child, group_by)	A relation representing a partitioning of rows by a key.
InnerJoin(left, right, predicate)
Intersect(left, right)	Intersection of two relations.
IntersectAll(left, right)	Non-unique intersection between two relations.
Join(left, right)
LeftJoin(left, right, predicate)
Limit(child, *, offset, limit)
Mutate(child, projections)	A relation representing appending columns to an existing relation.
Projection(child, projections)	A relation representing column selection.
Relation()	An abstract relation.
RightJoin(left, right, predicate)
Selection(child, predicate)	A relation of rows selected based on a predicate.
SetOperation(left, right)	An abstract set operation.
SortBy(child, order_by, null_ordering)	A relation representing rows of its child sorted by one or more keys.
Table(rows)
Union(left, right)	Union between two relations.
UnionAll(left, right)	Non-unique union between two relations.

class stupidb.core.Aggregation(child, metrics)

A relation representing aggregation of columns.

class stupidb.core.CrossJoin(left, right)

class stupidb.core.Difference(left, right)

Unique difference between two relations.

class stupidb.core.DifferenceAll(left, right)

Non-unique difference between two relations.

class stupidb.core.GroupBy(child, group_by)

A relation representing a partitioning of rows by a key.

group_by

A callable that takes an AbstractRow and returns an instance of typing.Hashable.

class stupidb.core.InnerJoin(left, right, predicate)

class stupidb.core.Intersect(left, right)

Intersection of two relations.

class stupidb.core.IntersectAll(left, right)

Non-unique intersection between two relations.

class stupidb.core.Join(left, right)

class stupidb.core.LeftJoin(left, right, predicate)

class stupidb.core.Limit(child, *, offset, limit)

class stupidb.core.Mutate(child, projections)

A relation representing appending columns to an existing relation.

class stupidb.core.Projection(child, projections)

A relation representing column selection.

child

aggregations

projections

class stupidb.core.Relation

An abstract relation.

class stupidb.core.RightJoin(left, right, predicate)

class stupidb.core.Selection(child, predicate)

A relation of rows selected based on a predicate.

predicate

A callable that takes an AbstractRow and returns a bool.

class stupidb.core.SetOperation(left, right)

An abstract set operation.

static itemize(mappings)

Return a hashable version of mappings.

class stupidb.core.SortBy(child, order_by, null_ordering)

A relation representing rows of its child sorted by one or more keys.

order_by

A callable that takes an AbstractRow and returns an instance of Comparable.

null_ordering

Whether to place the nulls of a column first or last.

class stupidb.core.Table(rows)

class stupidb.core.Union(left, right)

Union between two relations.

class stupidb.core.UnionAll(left, right)

Non-unique union between two relations.