# Filter previously stored entities **URL:** \ **Category:** Transformers\ **Tags:** entity-transformers\ **Created:** [November 3, 2022, 10:25am UTC](https://forum.alumio.com/t/filter-previously-stored-entities/257 "2022-11-03T10:25:27Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![Alumio\_Bot](https://forum.alumio.com/user_avatar/forum.alumio.com/alumio_bot/32/1824_2.png) [@Alumio\_Bot](https://forum.alumio.com/u/Alumio_Bot)\ **Post date:** [November 3, 2022, 10:25am UTC](https://forum.alumio.com/t/filter-previously-stored-entities/257/1 "2022-11-03T10:25:27Z")
### **Table Of Contents** - Use case - Video guide ### **Use case** In many cases, you might scramble for ways to boost the performance of an integration while designing it. For instance, let’s consider a case of a fileserver (FTP) having an XML file that contains thousands of products. Given its nature, detecting changes can be a challenging task as the XML file has no query functionality. Well, Alumio can sail you through this challenge by allowing you to utilize storage and building a delta filtering functionality, thanks to a fine-tuned **Filter Previously Stored Entities** transformer. This transformer bestows on you the capability to filter the already-processed entities using a dedicated storage called **Variant Cache**. As soon as you implement the transformer and run a test, you will see that the storage has stored the cache and it will be displayed. In case you change the cache and run it again, the storage will instantaneously capture the change and update it. Thus, the entire process of storing a cache system within the Alumio integration becomes a cakewalk. ### **Video guide** [![](https://alumio-forum.s3.dualstack.eu-central-1.amazonaws.com/uploads/original/1X/c3ec730e9c594d70f01d993a9b7aa7e39181c9e8.jpeg "Filter already processed entities - Improve integration performance by using storages as a cache") ](https://www.youtube.com/watch?v=0ZtI3f5HgKw)