# Appending data to a cache
## Introduction
We've already noted how the [add to cache](https://doc.wearepatchworks.com/product-documentation/process-flows/building-process-flows/process-flow-shapes/advanced-shapes/cache/add-to-cache-shape) shape can be added to a process flow to cache the entire payload at a given point in the flow. The default behaviour is that when a process flow runs and hits an **add to cache** shape, any existing data associated with that cache is overwritten with a new payload from the new run.
However, it is possible to **append** data to a cache, so each time the process flow runs and the **add to cache** shape is reached, the current cache is appended to the existing cache. This works for any cache type (**flow**, **flow run**, and **company**).
## Need to know
* **Paginated data**. If your connection shape receives paginated data, it's important to understand how the **save all pages** option works in conjunction with **append**. For more information please see our [cache pagination options page](https://doc.wearepatchworks.com/product-documentation/process-flows/building-process-flows/process-flow-shapes/advanced-shapes/cache/add-to-cache-shape/cache-pagination-options).
* **Cache size**. Theoretically, if a cache is set to append data and then runs on a regular basis indefinitely, the cache size may grow to an unmanageable size. With this in mind, a limit is in place to ensure that a single cache cannot exceed 50MB.
* **Append data format**. Appending cached data is supported for JSON only.
* **Shared caches.** The append to cache operation is not atomic - as such we advise against multiple process flows attempting to update the same cache at the same time.
## Using the append option
To use the **append** option, follow the steps below.
**Step 1**\
[Drop an add to cache shape into your process flow in the normal way](https://doc.wearepatchworks.com/product-documentation/process-flows/building-process-flows/process-flow-shapes/advanced-shapes/cache/add-to-cache-shape/..#adding-an-add-to-cache-shape-to-a-process-flow) - create your cache, then select it and add your cache key.
**Step 2**\
Ensure that the save all pages option is set as needed. For more information about how this option affects appended data please see our [cache pagination options page](https://doc.wearepatchworks.com/product-documentation/process-flows/building-process-flows/process-flow-shapes/advanced-shapes/cache/add-to-cache-shape/cache-pagination-options).
**Step 3**\
Enable the **append** option:
**Step 4**\
A **path to append to** field is displayed:
Here, you need to consider the structure of the payload that you're passing in and specify a path that ensures that each new payload is appended in the right place.
Example
Consider the payload below:
{% code lineNumbers="true" %}
```json
{
"orders": [
{
"id": 1,
"customer": {
"email": "joe.bloggs@wearepatchworks.com"
}
},
{
"id": 2,
"customer": {
"email": "jane.bloggs@wearepatchworks.com"
}
}
]
}
```
{% endcode %}
In this case, we want to append new data to the `orders` object, so our path to append to would be defined as `orders`. The first time the cache is updated, the payload would be:
{% code overflow="wrap" lineNumbers="true" %}
```json
[{"orders":[{"id":1,"customer":{"email":"joe.bloggs@wearepatchworks.com"}},{"id":2,"customer":{"email":"jane.bloggs@wearepatchworks.com"}}]}]
```
{% endcode %}
The next time the payload is appended, it would be in the form below:
{% code overflow="wrap" lineNumbers="true" %}
```json
{"0":{"orders":[{"id":1,"customer":{"email":"joe.bloggs@wearepatchworks.com"}},{"id":2,"customer":{"email":"jane.bloggs@wearepatchworks.com"}}]},"orders":[{"orders":[{"id":3,"customer":{"email":"dave.bowie@wearepatchworks.com"}},{"id":4,"customer":{"email":"michael.jagger@wearepatchworks.com"}}]}]}
```
{% endcode %}
{% hint style="info" %}
If required, [flow variables](https://doc.wearepatchworks.com/product-documentation/process-flows/building-process-flows/dynamic-variables/flow-variables) can be specified here.
{% endhint %}
**Step 5**\
Save the shape. Next time the process flow runs the data will be cached and appended.
## Viewing the appended cache
If you choose to view the payload for an **add to cache** shape, the payload will always show data from the latest run - for example:
However, when you add a load from cache shape, the payload will show ALL appended data so far - for example:
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