The timestamp column must already exist in the source table from which the base view or derived view is created. While using the Incremental Cache, a timestamp column is a requirement so that it can be used as a condition to enforce the data to be loaded incrementally. Below is the syntax for the condition:
lastmodifieddate > '@LASTCACHEREFRESH'
Additionally, Virtual DataPort must support pushing conditions down to the source over the last inserted/updated fields. If the condition cannot be pushed down to the source, Incremental mode is useless because the source will be forced to return the entire result set.
I suggest reading more about this in the “[Incremental Mode](https://community.denodo.com/docs/html/browse/8.0/en/vdp/administration/cache_module/cache_modes/incremental_mode#:~:text=Incremental%20Mode-,Incremental%20Mode,-The%20incremental%20mode)” section of the Virtual DataPort Administration Guide. Within this section, I recommend reading the “[Requirements a View Has to meet to Support Incremental Queries](https://community.denodo.com/docs/html/browse/8.0/en/vdp/administration/cache_module/cache_modes/incremental_mode#requirements-a-view-has-to-meet-to-support-incremental-queries)” section.
Hope this helps!