> ## Documentation Index
> Fetch the complete documentation index at: https://docs.alumio.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Storage: Track progress

> Tracks the progress of a data synchronization.

export const FormField = ({property, label, required = false, diType, uiPatterns, children}) => {
  const patterns = Array.isArray(uiPatterns) ? uiPatterns : uiPatterns ? [uiPatterns] : [];
  return <div style={{
    margin: '1.5rem 0'
  }}>
      <div style={{
    display: 'flex',
    alignItems: 'baseline',
    flexWrap: 'wrap',
    gap: '0.5rem',
    marginBottom: '0.25rem'
  }}>
        <strong>{label}</strong>
        <span style={{
    fontSize: '0.7rem',
    fontWeight: 600,
    textTransform: 'uppercase',
    letterSpacing: '0.04em',
    color: required ? '#6241f5' : '#6b7280'
  }}>
          {required ? 'Required' : 'Optional'}
        </span>
      </div>

      <div>{children}</div>

      {diType || patterns.length > 0 ? <p style={{
    fontSize: '0.85rem',
    color: '#6b7280',
    marginBottom: 0
  }}>
          {diType ? <>
              See the <a href={`/references/${diType}`}>{diType}</a> reference.{' '}
            </> : null}
          {patterns.length > 0 ? <>
              Accepts a <a href={`/documentation/placeholders-and-patterns/patterns#${patterns[0]}`}>pattern</a>.
            </> : null}
        </p> : null}
    </div>;
};

Records how far a data synchronization has got, so a later run can pick up where this one left off. For each record passing through, it reads an identifier and a date from your data and marks that identifier as finished at that date in the storage. Pair it with [Storage: Load progress](/references/transformer/storage-tracker-load-from-storage), which reads this progress back at the start of the next run, to build a flow that only processes new or changed records. The data flowing through your transformation is passed along unchanged.

This documentation describes: [Schema](/schemas/transformer/storage-tracker-save-in-storage)

## Fields

<FormField property="tracker" label="Storage" required diType="storage">
  The storage to record progress in. Point the [Storage: Load progress](/references/transformer/storage-tracker-load-from-storage) transformer at the same storage to read it back. See [Storage](/references/storage) for how to set one up.
</FormField>

<FormField property="datePath" label="Path to date" required>
  The path to the date in your data to record as the progress point, for example `updated_at`. This date must already be present in the data, otherwise the run stops with an error. Supports [placeholders](/references/placeholders).
</FormField>

<FormField property="identifierPath" label="Path to entity identifier" required>
  The path to the identifier in your data to mark as processed, for example `id`. Supports [placeholders](/references/placeholders).
</FormField>

<FormField property="format" label="Date format">
  The format the date at the path above is written in, so it can be read correctly, for example `Y-m-d\TH:i:sP`. Leave it empty to have the format detected automatically. See [the PHP date formats reference](https://www.php.net/manual/datetime.formats.php) for the available format codes.
</FormField>

## Sample data

This transformer writes progress into a configured storage and passes your data through unchanged, so it has no before/after of its own to show. The example below shows a typical configuration: for each record, the identifier at `id` is marked as processed at the date read from `updated_at`. A later [Storage: Load progress](/references/transformer/storage-tracker-load-from-storage) run pointed at the same storage would then report that identifier and date as the resume point.

| Field                     | Value                           |
| ------------------------- | ------------------------------- |
| Storage                   | A configured storage            |
| Path to date              | `updated_at`                    |
| Path to entity identifier | `id`                            |
| Date format               | (empty, detected automatically) |

```json Configuration theme={null}
{
  "prototype": "storage-tracker-save-in-storage",
  "parameters": {
    "tracker": { "prototype": "storage", "parameters": {} },
    "datePath": "updated_at",
    "identifierPath": "id"
  }
}
```