This article will explain what are live mode and sample mode and how to use them
Sample mode and Live mode are located on the right of the top toolbar
Sample mode: When turned on, Sample mode will display 50 random rows from the entire feed
Live mode: When turned on, filters and actions will be applied in real-time for all items. When Live mode is turned off, the Execute button will appear 
. When clicked it will apply the actions/filters for all items in the feed.
These actions are useful when working on feeds containing many rows or when wanting to apply at once several actions/filters, as it will help avoid long loading times.