# Add sequence The **Add sequence** step adds a sequence to the PDI stream. A sequence is an ever-changing integer value with a specific start and increment value. You can either use a database sequence to determine the value of the sequence, or have it generated by PDI. PDI-generated sequence values are unique when used in the same transformation, and return to the same starting value each time you run the transformation. ### General options Enter the following information: | Option | Description | | ----------------- | ------------------------------------------------------------------------------------------------ | | **Step name** | Specify the unique name of the step on the canvas. The default is `Step sequence`. | | **Name of value** | Specify the name of the new sequence value to add to the PDI stream. The default is `valuename`. | ### Generate a sequence with a transformation counter (PDI) ![Use a transformation counter to generate the sequence](/files/UwWbBtemE9twYj9lJ9jm) The following table contains options for generating a sequence from a PDI transformation counter: | Option | Description | | -------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Use counter to calculate sequence?** | Select this checkbox to generate the sequence in PDI. This option is selected by default. If you clear this checkbox, **Use DB to generate the sequence?** is selected automatically. | | **Counter name (optional)** | Specify the counter name if multiple steps in a transformation generate the same value name, to avoid creating separate sequences for each step. | | **Start at value** | Specify the value to start the sequence. For example, if **Start at value** is set to `1`, the sequence starts with `1`. If **Start at value** is set to `0`, the sequence starts with `0`. | | **Increment by** | Specify the amount by which the sequence increases or decreases. | | **Maximum value** | Specify the value to reach before the sequence returns to the **Start at value** setting. | For example: * If you set **Start at value** to `1`, **Increment by** to `1`, and **Maximum value** to `3`, the resulting sequence is `1, 2, 3, 1, 2, 3, 1, 2`... * If you set **Start at value** to `0`, **Increment by** to `-1`, and **Maximum value** to `-2`, the resulting sequence is `0, -1, -2, 0, -1, -2, 0`... ### Generate a sequence with a database sequence ![Add sequence step](/files/pfnWxF3e1wQE64Uk0zeV) The following table contains options for generating a sequence from a database: | Option | Description | | ------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Use DB to generate the sequence?** | Select this checkbox if you want the sequence to be driven by a database sequence. If you clear this checkbox, **Use counter to calculate sequence?** is selected automatically. **Use counter to calculate sequence?** is selected by default. | | **Connection** | Select the connection where your database sequence resides. If you do not have an existing connection, select **New** or **Wizard**. To modify an existing connection, select **Edit**. | | **Schema name** (optional) | Specify the schema name of any related table. Select **Schemas** to choose a schema within the database specified for **Connection**. | | **Sequence name** | Specify the name of the database sequence. Select **Sequences** to choose a sequence within the database specified for **Connection**. | ### See also The following transformation steps may also be useful when working with sequences: * [**Add value fields changing sequence**](https://wiki.pentaho.com/display/EAI/Add+value+fields+changing+sequence): Adds a sequence when the values of a field change. Each time a value of at least one field changes, the added sequence resets to its starting point. * [**Group By**](/pdia-data-integration/10.2-data-integration/pdi-transformation-steps-reference-overview/group-by-landing-page-article.md): Builds aggregates by grouping and generates sequential numbers within rows with repeating values. See the [Get ID from Slave Server](https://wiki.pentaho.com/display/EAI/Get+ID+from+Slave+Server) step if you need a unique ID in a clustered environment. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. 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