How does Oracle metadata get refreshed immediately in Dremio? Out-of-the-box dremio seems to be aware of the new changes to Oracle schema changes once an hour i.e. when a table/view gets created in an Oracle schema, Dremio registers the fact one hour later.
As refreshing metadata can be an expensive operation (and considering that in most cases, schemas might not be changing often), Dremio has several options to configure how and when to refresh metadata: https://docs.dremio.com/advanced-administration/metadata-caching.html.