> For the complete documentation index, see [llms.txt](https://docs.whalesync.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.whalesync.com/features/filters.md). # Filters

Adding a filter that will only sync records when a particular field is true

### Filter settings can only be edited *before* the initial sync When you are creating a new table mapping, you are able to set filters. Once data in those tables sync, you cannot change the filter settings.
### Filters sync the *final* update before future updates are excluded For instance, if you change a record from ‘John’ to ‘Sarah’ in Google Sheets, Whalesync will sync this last update to Affinity. After that final sync, changes to the now 'Sarah' record will be filtered out.

Updating a record in a way that removes it from the filter

## FAQ ### **Will setting a filter delete any of my existing data?** No, adding a filter won’t remove existing data. Filters apply to any *future* updates. ### **Are filters case sensitive?** Yes.

This will only sync records that equal "John" and will not sync records that equal "john"

### **How should I write percentage values?** Percentage values should be written as numbers.

This will only sync records that have a "Percent" value above 10%

### Is there any way I can edit a filter after the initial sync? Unfortunately Whalesync does not support editing a sync filter after a sync has been turned on. However, by using [record matching](/features/record-matching.md), you can work around this. Let's say you have a sync between App A and App B. By deleting the existing sync and creating a new sync, you can effectively edit the filter: 1. Make sure that all records in synced tables have a unique identifier that can be used for record matching 2. Delete the original sync between App A and App B 3. Create a new sync between App A and App B 4. Create the desired filter 5. When asked how you wish to match up existing records (via [record matching](/features/record-matching.md)), choose the unique identifier you made a note of in step 1 Now you should have a working sync that has the same configuration as the original sync, but with the new filter.