Delete Duplicates: Example of Creating

This article describes an example of creating and executing an ETL task with deleting duplicate values at the output.

The repository must contain three tables: T_Source, T_Destination and T_Duplicate. Tables must be identical in structure, the field with the Value identifier is present, this field is used to check for duplicates. The repository must also contain an ETL task with the ETLTASKS identifier. On executing the example presented below four objects are created in the ETL task: repository source, the Delete Duplicates converter and two consumers (unique data goes to the first one , and duplicates - to the second one). The required properties and links are set for all objects:

After objects are created and saved, the ETL task is executed. The similar code applied to different objects is placed into separate procedures or functions.

Add links to the Andy, Db, Drawing, Dt, Etl, Metabase system assemblies.

Sub UserProc;
Var
    MB: IMetabase;
    ETLTask: IEtlTask;
    EtlProvider: IEtlPlainDataProvider;
    MetabaseProvider: IDtMetabaseProvider;
    EtlConsumer, DuplicateConsumer: IEtlPlainDataConsumer;
    MetabaseConsumer, MetabaseConsumer1: IDtMetabaseConsumer;
    Deduplicate: IEtlPlainDataDeduplicate;
    Index: IEtlPlainIndex;
    Link, Link1, Link2: IEtlPlainLink;
    Shapes: IWxShapes;

    ProvFields, DedupInFields, DedupOutFields, DedupOutDIFields, ConsFields, DupConsFields: IEtlPlainFields;
Begin
//Open ETL task
    MB := MetabaseClass.Active;
    ETLTask := MB.ItemById("ETLTASKS").Edit As IEtlTask;
//Create a provider
    EtlProvider := ETLTask.Create(EtlObjectType.PlainDataMetabaseProvider) As IEtlPlainDataProvider;
    EtlProvider := EtlProvider.Edit;
    EtlProvider.Id := "Metabase_Provider";
    EtlProvider.Name := "Import from table";
    MetabaseProvider := EtlProvider.Provider As IDtMetabaseProvider;
    MetabaseProvider.Dataset := MB.ItemById("T_Source").Bind As IDatasetModel;
    EtlProvider.FillDefault;

     //Create a visual object of provider
    CreateWX(ETLTask, EtlProvider, -60, 0);
//Create a consumer
    EtlConsumer := ETLTask.Create(EtlObjectType.PlainDataMetabaseConsumer) As IEtlPlainDataConsumer;
    EtlConsumer := EtlConsumer.Edit;
    EtlConsumer.Id := "Metabase_Consumer";
    EtlConsumer.Name := "Export to table";
    MetabaseConsumer := EtlConsumer.Consumer As IDtMetabaseConsumer;
    MetabaseConsumer.Dataset := MB.ItemById("T_Destination").Bind As IDatasetModel;
     //Create a visual object of consumer
    CreateWX(ETLTask, EtlConsumer, 60, 0);
//Create a consumer for duplicates
    DuplicateConsumer := ETLTask.Create(EtlObjectType.PlainDataMetabaseConsumer) As IEtlPlainDataConsumer;
    DuplicateConsumer := DuplicateConsumer.Edit;
    DuplicateConsumer.Id := "Duplicate_Consumer";

    DuplicateConsumer.Name := "Duplicates export";
    MetabaseConsumer1 := DuplicateConsumer.Consumer As IDtMetabaseConsumer;
    MetabaseConsumer1.Dataset := MB.ItemById("T_Duplicate").Bind As IDatasetModel;
     //Create a visual object of consumer
    CreateWX(ETLTask, DuplicateConsumer, 60, 20);
//Create the "Duplicates Removal" object
    Deduplicate := ETLTask.Create(EtlObjectType.PlainDataDeduplicate) As IEtlPlainDataDeduplicate;
    Deduplicate := Deduplicate.Edit;
    Deduplicate.Id := "Deduplicate_Transform";
    Deduplicate.Name := "Duplicates removal";

    Deduplicate.Rule := EtlAgregateFormula.Min; //Record satisfies condition
    Deduplicate.Expression.AsString := "True";
     //Create a visual object of transformer
    CreateWX(ETLTask, Deduplicate, 0, 0);
//Fill field lists of all objects based on provider field list
     //Get list of fields
    ProvFields := EtlProvider.PlainOutput.Fields; //Provider output
    DedupInFields := Deduplicate.PlainInput.Fields; //Transformer input
    DedupOutFields := Deduplicate.PlainOutput.Fields; //Transformer output
    DedupOutDIFields := Deduplicate.DuplicatePlainOutput.Fields; //Output for saving duplicates
    ConsFields := EtlConsumer.PlainInput.Fields; //Consumer input
    DupConsFields := DuplicateConsumer.PlainInput.Fields; //Input of duplicates consumer
     //Fill lists of fields
    FillFields(DedupInFields, ProvFields);
    FillFields(DedupOutFields, DedupInFields);
    FillFields(DedupOutDIFields, DedupInFields);

    FillFields(ConsFields, DedupOutFields);
    FillFields(DupConsFields, DedupOutDIFields);
     //Set up transformer index
    Index := Deduplicate.Index.Edit;
    Index.AddField;
    Index.PlainInputField(0, 0) := DedupInFields.FindById("VALUE");
    Index.Save;
//Save all objects
    EtlProvider.Save;
    Deduplicate.Save;
    EtlConsumer.Save;

    DuplicateConsumer.Save;
//Link of transformer with all objects
     //Create links
    Link := CreateLink(ETLTask, EtlProvider.PlainOutput, Deduplicate.PlainInput);
    Link1 := CreateLink(ETLTask, Deduplicate.PlainOutput, EtlConsumer.PlainInput);
    Link2 := CreateLink(ETLTask, Deduplicate.DuplicatePlainOutput, DuplicateConsumer.PlainInput);
     //Create visual links
    Shapes := ETLTask.Workspace.Shapes;
    CreateWXLink(ETLTask, Shapes.FindById(EtlProvider.Id), Shapes.FindById(Deduplicate.Id), Link);
    CreateWXLink(ETLTask, Shapes.FindById(Deduplicate.Id), Shapes.FindById(EtlConsumer.Id), Link1);
    CreateWXLink(ETLTask, Shapes.FindById(Deduplicate.Id), Shapes.FindById(DuplicateConsumer.Id), Link2);

//Save task
    (ETLTask As IMetabaseObject).Save;
//Execute task
    ETLTask.Execute(Null);
End Sub UserProc;
//Create visual objects
Sub CreateWX(ETLTask: IEtlTask; ETLObject: IEtlObject; XPosition: Integer; YPosition: Integer);
Var
    WxRect: IWxRectangle;
    WxETLObj: IWxEtlObject;
Begin
    WxRect := ETLTask.Workspace.CreateRectangle;
    WxRect.Id := ETLObject.Id;
    WxETLObj := New WxEtlObject.Create;
    WxETLObj.EtlObject := ETLObject;
    WxRect.Style.TextPosition := WxTextPosition.Bottom;

    WxRect.Style.PictureMarginTop := -10;
    WxRect.PinPosition := New GxPointF.Create(XPosition, YPosition);
    WxRect.Extension := WxETLObj As IWxShapeExtension;
End Sub CreateWX;
//Fill lists of input/output fields
Sub FillFields(Fields, FieldsSource: IEtlPlainFields);
Begin
    Fields := Fields.Edit;
    Fields.Fill(FieldsSource);
    Fields.Save;
End Sub FillFields;
//Create a link between objects
Function CreateLink(ETLTask: IEtlTask; Output: IEtlPlainOutput; Input: IEtlPlainInput): IEtlPlainLink;
Var
    Link: IEtlPlainLink;
Begin
    Link := ETLTask.CreatePlainLink;
    Link.SourceObjectOutput := Output;

    Link.DestinationObjectInput := Input;
    Link.FillDefault;
    Return Link;
End Function CreateLink;
//Create visual links
Sub CreateWXLink(ETLTask: IEtlTask; Shape1: IWxShape; Shape2: IWxShape; Link: IEtlPlainLink);
Var
    WLink: IWxLink;
    WxETLLink: IWxEtlObject;
Begin

     //Create visual link objects
    WLink := ETLTask.Workspace.AutoLinkShapes(Shape1, Shape2);
    WLink.Style.LinePenBeginWxCap := WxLineCap.Flat;
    WLink.Style.LinePenEndWxCap := WxLineCap.Arrow30DegreeFilled;
    WxETLLink := New WxEtlObject.Create;
    WxETLLink.EtlObject := Link;
    WLink.Extension := WxETLLink As IWxShapeExtension;
End Sub CreateWXLink;