Memory Architecture (contd)
- list of referenced objects + exec plan =>lib.cache
- lib.cache is very useful in OLTP since many users fire same SQL; hence compilation and operational costs are saved. But this is not so useful in data warehousing as it may not have common SQL across users.
- Oracle uses LRU on shared pool. SQL statements, dictionary elements are timestamped.
- contains private memory for each user session.
- for tracking query execution, locally declared variables, additional sort memory, etc.