Let's say we are inserting a new row in DB table. Is it possible to create a

A poller is a generic term used to a design pattern that executes at a regular interval of time and does a unit of work. Think of it as a cron job. What Mike is saying here is that you will have a process where the start event will be configured as a Timer event (you can specify the duration) and it fires on a regular basis.
I would suggest that you ensure that the process is immediately cleared from memory in order to avoid data being retained in Appian for no reason. This will keep your memory lean.

A poller is a generic term used to a design pattern that executes at a regular interval of time and does a unit of work. Think of it as a cron job. What Mike is saying here is that you will have a process where the start event will be configured as a Timer event (you can specify the duration) and it fires on a regular basis.
I would suggest that you ensure that the process is immediately cleared from memory in order to avoid data being retained in Appian for no reason. This will keep your memory lean.