DB_KEEP_CACHE_SIZE, DB_RECYCLE_CACHE_SIZE

Question

The keep buffer pool retains the schema objects in the memory. and the recycle buffer pool eliminates the data blocks from the memory as soon as they are no longer needed.
Now i have a table shares with 230Mb of dataa (approx 34M rows).
i use the alter table shares cache; statement to indicate that the blocks of the segment shares have to be kept in the memory.
i use the alter table shares nocache; statement to indicate the blocks should be removed once the work is done.
1. am i correct for the above statements regarding using the cache and nocache option.
2. can any one tell me how to specify htat the blocks of a particular segment have to be in keep cache. if the above statement is false.
3. please guys, can any one explain me the details regarding how to cache. and how to use recycle cache size for segments.

Answer 1

Hi vishnusivathej ,
Default cache: blocks will be kept or remove from database buffer cache based on LRU (Least Recent Used).
Recycle cache: blocks will be removed from database buffer cache after being issued
Keep cache: : blocks will be remain in database buffer cache
You cannnot assign a db cache based on segment. This is a storage option for an entire object, unless you have a partitioned table (then you can define which cache to use on a partition level).
Syntax:
alter TABLE <schema>.<table_name> storage (buffer_pool keep);
alter INDEX <schema>.<index_name> storage (buffer_pool keep);
You can refer to the following discussions as well:
http://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:23558719922648
http://www.dba-oracle.com/t_script_automate_keep_pool_tables_indexes.htm
HTH,
Thierry
Note: the use of the keep pool is intended for small / frenquently used tables (lookup tables). I implemented this some time ago, and acheived a substantial increase of performance.
Edited by: Urgent-IT on Feb 2, 2011 9:00 AM