Questions relate to table "cache"??

Question

We plan to "cache" some tables to SGA or DB_keep_cache_size. some questions need to clarify:
1. what different between:
alter table user.table_name cache;
alter TABLE USER.TABLE_NAME storage (buffer_pool keep);
2. if I using either way to cache table, how to check table already "cache"?
Thanks.

Answer 1

ef8454 wrote:
We plan to "cache" some tables to SGA or DB_keep_cache_size. some questions need to clarify:
1. what different between:
alter table user.table_name cache;
alter TABLE USER.TABLE_NAME storage (buffer_pool keep);
2. if I using either way to cache table, how to check table already "cache"?
Thanks.In Oracle, starting with I suppose Release 8, they have three types of data buffer pool, or say they have divided data buffer pool, in three part,
1) Default pool -- This is the normal data pool.
2) Keep Pool -- This is a data pool where you want your table/object to remain in memory for longer time.
3) Recycle Pool -- This is a data pool where you want your table/object to remain till the time it is needed i.e. very short duration.
So when you use second command with storage option, you are saying to keep that data in Keep Pool.
Now, in all the three pools data gets aged out based on an algorithim known as LRU (Least recently used) i.e. to keep the data in front of the queue if it is accessed.
When you say cache using your first query, you are saying oracle to keep it in the front of the queue when full table scan is done. It can be in any buffer (Default/Keep/Recycle)
Regards
Anurag