Just a quick tip for SECUREFILE lobs.
You may be familiar with basic compression on data in tables. It is a dictionary attribute of the table, which is then taken into account when you perform:
- a SQL Loader direct load, or
- an INSERT with the APPEND hint, or
- a bulk bind INSERT in PLSQL using the APPEND_VALUE hint.
Whichever of the above you perform does not really matter – the key thing is that when you set the COMPRESS attribute on a table, this only applies on operations subsequent to the moment at which you altered the table. It does not compress the existing data. Hence when you alter a table to add the attribute, it is instantaneous.