For non file system sources, the default is one hour where we look for new tables, open the source settings on Dremio and click on the metadata tab and then see “Dataset Discovery”
For new columns added, look just below for “Dataset Details”
Here is the full documentation on this
http://docs.dremio.com/advanced-administration/metadata-caching.html
Once we discover a table via the light probe “Data set discovery” we would add it to information_schema, this does not mean we collect metadata (dataset details), we only do it for objects that have atleast been queries once