# IndexGenerator
{% hint style="info" %}
In previous versions of RDT, this transformer was called `IDGenerator`.
{% endhint %}
**Compatibility:** `id` data
The `IndexGenerator` is used to create an indexed ID column that you may be using as a primary key. When transforming the data, it removes the column. When reversing the the transform, it creates an indexed ID column starting at a specified counter, with any additional prefixes or suffixes you provide.
```python
from rdt.transformers.text import IndexGenerator
transformer = IndexGenerator(prefix='ID_', starting_value=0, suffix='-synthetic')
```
## Parameters
**`prefix`**: A string with the prefix to use for the counter. All generated IDs will have the prefix.
(default) None
Do not add a prefix
<string>
Add the prefix to every ID
**`starting_value`**: The starting value for the counter
(default) 0
Start the counter at 0.
<integer>
Use the integer as the starting value. This must be >=0.
**`suffix`**: A string with the suffix to use for the counter. All generated IDs will have the suffix.
(default) None
Do not add a suffix
<string>
Add the suffix to every ID
## FAQs
Will the generated IDs always be unique?
Yes. The generated IDs start at the `starting_value` parameter, and always increment by 1 for each new ID. Since there is no maximum value, the transformer will create unique IDs. (This is useful for primary keys.)
**Tip:** Use the [reset\_randomization](/rdt/usage/hypertransformer/transformation.md#reset_randomization) method to reset the counter back to the original `starting_value`.
When should I use this transformer?
The `IndexGenerator` is useful for ID columns that do not have any mathematical meaning. This transformer is useful for columns that represent indexed IDs, such as a primary key column.
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