Class JoinMergeSortedTransformBase<TDerived, TLeftInput, TRightInput, TOutput>
An abstract dataflow worker with two input ports and one Output port, that performs a
merge-join on the two presorted inputs (except for a cross join which does not
require sorted inputs).The row order on the inputs must match the ordering specified to the
constructor.
Note that both inputs must be presorted according to the order specified by the comparison
function (provided by the rowComparerCommandAction parameter or the Comparison property),
including collation order for textual columns, where in the order any nulls appear and
if nulls are equal to each other or not.
Note: Unless you supply the output function yourself, any column that is copied to multiple downstream columns must support multi-copy.
Non-cross-joins are
partially blocking
on the RightInput input port:
when a join is found, it will buffer all rows from the RightInput port that compare equal
to the join rows. This consumes "Number of RightInput rows comparing equal" multiplied by
"Memory per RightInput row". To conserve memory, link RightInput to the upstream
output with the expected smallest memory consumption.
Cross-joins are instead fully blocking on the RightInput input port,
and will buffer all rows from the RightInput port.
Note that this base class is not used directly by library users. Instead use CrossJoinTransformFactory, FullJoinMergeSortedTransformFactory, InnerJoinMergeSortedTransformFactory, LeftJoinMergeSortedTransformFactory, or RightJoinMergeSortedTransformFactory.
Inheritance
Implements
Inherited Members
Namespace: actionETL
Assembly: actionETL.dll
Syntax
public abstract class JoinMergeSortedTransformBase<TDerived, TLeftInput, TRightInput, TOutput> : WorkerBase<TDerived>, IDisposeOnFinished where TDerived : JoinMergeSortedTransformBase<TDerived, TLeftInput, TRightInput, TOutput> where TLeftInput : class where TRightInput : class where TOutput : class, new()Type Parameters
| Name | Description |
|---|---|
| TDerived | The type of the derived worker. |
| TLeftInput | The type of each |
| TRightInput | The type of each |
| TOutput | The type of each |
Properties
Comparison
Gets or sets the comparison function that compares left and right input rows. Cannot be set after the worker has started running. Cannot be set at all for the cross-join transform.
For non-cross-join transforms: can be null, although either
rowComparerCommandAction must be provided to the constructor,
or the Comparison property must be set.
The function must evaluate to
-1 if TLeftInput is smaller than TRightInput,
0 if they are equal, and 1 if TLeftInput is bigger than TRightInput.
Note: This property is thread-safe.
///Declaration
public Comparison<TLeftInput, TRightInput> Comparison { get; set; }Property Value
| Type | Description |
|---|---|
| Comparison<TLeftInput, TRightInput> | The comparison function callback. |
Exceptions
| Type | Condition |
|---|---|
| InvalidOperationException | Cannot set the value after the worker has started running. |
LeftInput
Gets the left input port for consuming rows from the left upstream worker.
Declaration
public InputPort<TLeftInput> LeftInput { get; }Property Value
| Type | Description |
|---|---|
| InputPort<TLeftInput> | The left input port. |
Output
Gets the output port for sending rows to the downstream worker.
Declaration
public OutputPort<TOutput> Output { get; }Property Value
| Type | Description |
|---|---|
| OutputPort<TOutput> | The output port. |
RightInput
Gets the right input port for consuming rows from the right upstream worker.
Declaration
public InputPort<TRightInput> RightInput { get; }Property Value
| Type | Description |
|---|---|
| InputPort<TRightInput> | The right input port. |
Methods
RunAsync()
This method can be overridden to add custom functionality to the derived worker that runs before
and after the row processing. In this case, the base class base.RunAsync() must
be called for the worker to function correctly.
Typically, these classes are used without overriding this method.
Declaration
protected override async Task<OutcomeStatus> RunAsync()Returns
| Type | Description |
|---|---|
| Task<OutcomeStatus> | A |
Overrides
Exceptions
| Type | Condition |
|---|---|
| InvalidOperationException |