dbashashi

 Profile Answers by dbashashi 

• Dec 2nd, 2010

 

Hi,
Db_buffer_Cache is nothing but a memory allocated out of physical Memory (RAM) and is part of SGA.
When the database server starts for the first time the DB_buffer_cache doesnt have any information stored in it. Initially phyical reads are done to get the data into buffer cache from datafiles. Only after some time we see the db_cache has some data stored upto its limit and flushing the not so frequently used data using LRU method.
Now if any querry comes with something which is already there in the buffer cache it does not have to do physical reads from the disk(Hard Parsing) and it uses it, thus making thing faster.