Operators in View Models

WorkSpace Data Federation provides a selection of elements and operators you can use to manipulate data in a view model.

Beginning and ending data flows

Two important elements identify the beginnings and the end of the flow in a view model:

Input Source
Use Input Source elements to specify where the data for your view model comes from, such as existing data services (deployed view models), database operations, or grid files. A view model can have zero or more input sources.
Result
WorkSpace Data Federation puts a Result element at the end of each view model’s data flow. A view model has one result.

Relational operations

These operators let you perform SQL-style operations:

Select
Given one input result set and a Boolean where expression, Select produces a new result set containing the input rows for which the where expression evaluates to true.
Projection
Projection lets you modify the schema—you can remove columns, add computed columns, or apply formulas to alter existing column values.
Order By
Given one input result set and your specification of which column(s) to sort on and whether to sort in ascending or descending order, Order By produces a new result set in which the content of the input is sorted.
Aggregate
WorkSpace Data Federation provides a number of predefined aggregation functions (including sum, count, average, minimum, and maximum). Given one input result set, Aggregate produces a new, single-row result set by applying aggregate functions to the input.
Group By
Group By uses the same aggregation functions used in Aggregate. Given one input result set, Group By applies aggregate functions to the input and groups the rows in the result set according to input columns you specify.
Join
Given two input result sets that share a common column, Join combines rows and produces a new result set. Join supports Inner, Outer-left, Outer-right, and Outer-full join types, as well as three join algorithms: Sort Merge Join, Hash Join, and Nested Loop Join.
Union
Given two input result sets with identical schemas, Union generates a single result set that includes everything in both inputs.
Intersection
Given two input result sets with identical schemas, Intersection generates a result set containing only rows that are present in both inputs.

Advanced operations

Additional operators let you perform more powerful manipulations:

Multiplexer
Given up to five inputs and a conditional expression for each, Multiplexer generates a result set in which all the input result sets whose conditional expressions evaluate to true are concatenated. You can use Multiplexer to select from among several choices and to concatenate the selected result sets into a single result set.
Iterator
Iterator executes its primary input repeatedly; the number of iterations is determined by an input parameter or by an optional secondary input. For example, you can perform a computation once for every date in a range, or get account numbers and balances for every social security number in a list. You can also specify a condition to terminate the iteration. Iterations may be nested.
Splitter
Given one input result set, Splitter routes input to multiple, identical output result sets without necessarily recomputing its input. It can also cache its output.
Generator
Generator creates a new result set based on JavaScript expressions and a schema that you supply.
Update
Using a database operation, Update inserts data into an external database. Each update is a transaction separate from the data service itself.
Custom
Using JavaScript logic that you supply, Custom performs an operation of your design.

Aggregate Operator
The Aggregate operator condenses a multi-row result set into a single-row result set by applying any of a number of functions to the data.
Custom Operator
A Custom operator can perform any operation that you define, using JavaScript code that you supply.
Generator Operator
A Generator operator produces a result set without input.
Group By Operator
The Group By operator lets you divide input rows into groups and apply aggregate functions to produce an output row for each group. The Group By operator is similar to the Aggregate operator.
Intersection Operator
The Intersection operator produces a result set consisting of only those rows that are common to both of its inputs.
Iterator Operator
The Iterator operator provides a looping construct for view models.
Join Operator
The Join operator performs a relational join operation on its two input result sets, matching up corresponding rows from the inputs. It does this matching by checking for equality of one or more pairs of columns (where column “A” of the first result set matches column “B” of the second, for example).
Multiplexer Operator
Given up to five input result sets and a conditional expression for each, the Multiplexer operator generates a result set that concatenates all the inputs whose conditional expressions evaluate to true.
Order By Operator
The Order By operator sorts its input based on the criteria you specify.
Projection Operator
The Projection operator lets you modify a schema.
Select Operator
Use a Select operator to filter rows from an input result set.
Splitter Operator
Given one input result set, the Splitter operator produces one or more identical output result sets. Use Splitter if you need to operate on the same data in multiple execution paths within your view model.
Union Operator
The Union operator produces a single result set that is the union of its two input result sets—a combination of everything in both inputs.
Update Operator
Use the Update operator to invoke a database operation that performs SQL insert or update operations against a connected database.

Parent topic: View Models

Parent topic: Adding an Operator

Related concepts

Input Source Element

Result Element