TableAlgebra-0.1.5: Ferry Table Algebra

Database.Ferry.Algebra

Description

This package provides a convenient interface to construct Table Algebra plans that can be dealt with by Pathfinder (http:www-db.informatik.uni-tuebingen.deresearchpathfinder). A describtion of the algebra can be found at: http:dbworld.informatik.uni-tuebingen.deprojectspathfinderwikiLogical_Algebra This module only provides a subset of the complete algebra.

Synopsis

# Documentation

type AlgPlan = (Map Algebra AlgNode, AlgRes)Source

An algebraic plan is the result of constructing a graph. | The pair consists of the mapping from nodes to their respective ids | and the algres from the top node.

Union between two plans

attach :: ResAttrName -> ATy -> AVal -> AlgNode -> GraphM AlgNodeSource

Attach a column `ResAttrName` of type `ATy` with value `AVal` in all rows to table `AlgNode`

proj :: ProjInf -> AlgNode -> GraphM AlgNodeSource

Project/rename certain column out of a plan

Get the current loop table

rownum :: AttrName -> [AttrName] -> Maybe AttrName -> AlgNode -> GraphM AlgNodeSource

Similar to rowrank but this will assign a emph{unique} number to every row (even if two rows are equal)

rownum' :: AttrName -> [(AttrName, SortDir)] -> Maybe AttrName -> AlgNode -> GraphM AlgNodeSource

Same as rownum but columns can be assigned an ordering direction

Join two plans where the columns n1 of table 1 and columns n2 of table 2 are equal.

rank :: ResAttrName -> SortInf -> AlgNode -> GraphM AlgNodeSource

Assign a number to each row in column `ResAttrName` incrementing sorted by `SortInf`. The numbering is not dense!

eqTJoin :: [(String, String)] -> ProjInf -> AlgNode -> AlgNode -> GraphM AlgNodeSource

The same as eqJoin but with multiple columns.

Remove duplicate rows

rowrank :: ResAttrName -> SortInf -> AlgNode -> GraphM AlgNodeSource

Same as rank but provides a dense numbering.

cast :: AttrName -> ResAttrName -> ATy -> AlgNode -> GraphM AlgNodeSource

Cast column `AttrName` to type `ATy` and give it the name `ResAttrName` afterwards.

Compute the difference between two plans.

aggr :: [(AggrType, ResAttrName, Maybe AttrName)] -> Maybe PartAttrName -> AlgNode -> GraphM AlgNodeSource

Apply aggregate functions to a plan

select :: SelAttrName -> AlgNode -> GraphM AlgNodeSource

Select rows where the column `SelAttrName` contains True.

posSelect :: Int -> SortInf -> Maybe AttrName -> AlgNode -> GraphM AlgNodeSource

Get's the nth element(s) of a (partitioned) table.

Construct a database table node The first argument is the emph{qualified} name of the database table. The second describes the columns in alphabetical order. The third argument describes the database keys (one table key can span over multiple columns).

notC :: AttrName -> AttrName -> AlgNode -> GraphM AlgNodeSource

Negate the boolen value in column n and store it in column r

Make cross product from two plans

oper :: String -> ResAttrName -> LeftAttrName -> RightAttrName -> AlgNode -> GraphM AlgNodeSource

Apply an operator to the element in `LeftAttrName` and `RightAttrName`, store the result in `ResAttrName`

Construct an empty table node with

withBinding :: String -> AlgRes -> GraphM a -> GraphM aSource

Evaluate the graph construction computation with the current environment extended with a binding n to v.

withContext :: Gam -> AlgNode -> GraphM a -> GraphM aSource

Evaluate the graph construction computation with a differnt gamma, | and loop table. Return within he current computational context.

Get the current variable environment

Lookup a variable in the environment

nat :: Integer -> AValSource

Create an algebraic nat value

int :: Integer -> AValSource

Create an algebraic int value

bool :: Bool -> AValSource

Create an algebraic boolean value

double :: Double -> AValSource

Create an algebraic double value

string :: String -> AValSource

Create an algebraic string value

Types of algebraic values

data SortDir Source

Sorting rows in a direction

Constructors

 Asc Desc

Instances

 Eq SortDir Ord SortDir Show SortDir The show instance results in values that are accepted in the xml plan.

data AggrType Source

Constructors

 Avg Max Min Sum Count All Prod Dist

Instances

 Eq AggrType Ord AggrType Show AggrType

newtype SubPlan Source

Constructors

 SubPlan (Map Int AlgRes)

Instances

 Show SubPlan

type AlgRes = (AlgNode, Columns, SubPlan)Source

An algebraic solution is a triple consisting of the node id, a description of the database columns and all subplans

data Column whereSource

The column data type is used to represent the table structure while compiling ferry core into an algebraic plan The col column contains the column number and the type of its contents The NCol column is used to group columns that together form an element of a record , its string argument is used to represent the field name.

Constructors

 Col :: Int -> ATy -> Column NCol :: String -> Columns -> Column

Instances

 Show Column

type Columns = [Column]Source

One table can have multiple columns

data ATy whereSource

Algebraic types At this level we do not have any structural types anymore those are represented by columns. ASur is used for surrogate values that occur for nested lists.

Constructors

 AInt :: ATy AStr :: ATy ABool :: ATy ADec :: ATy ADouble :: ATy ANat :: ATy ASur :: ATy

Instances

 Eq ATy Ord ATy Show ATy Show the algebraic types in a way that is compatible with the xml plan.

type SchemaInfos = [(AttrName, ATy)]Source

Schema information, represents a table structure, the first element of the tuple is the column name the second its type.

type KeyInfos = [KeyInfo]Source

Multiple keys

type GraphM = ReaderT (Gam, AlgNode) (State (Int, Map Algebra AlgNode))Source

Graphs are constructed in a monadic environment. | The graph constructed has to be a DAG. | The reader monad provides access to the variable environment Gamma and the loop table | The variable environment is a mapping from variable names to graphnodes that represent | their compiled form. | The state monad gives access to a supply of fresh variables, and maintains a map from | nodes to node ids. When a node is inserted and an equal node (equal means, equal node | and equal child nodes) already exists in the map the node id for that already existing | node is returned. This allows maximal sharing.

type Gam = [(String, AlgRes)]Source

Variable environemtn mapping from variables to compiled nodes.

initLoop :: AlgebraSource

Shorthand for the initial loop condition used by Ferry.

runGraph :: Algebra -> GraphM AlgRes -> AlgPlanSource

Evaluate the monadic graph into an algebraic plan, given a loop relation.