Im sure this is an easy one for an experienced dba, but i need to find the size of an instance, ive looked at v$sga this tells me fixed size, variable size, database buffers, redo buffers but i do not know if this is enough, is there a query i can do to get a reasonable indication of the size of an instance?
1. buffer cache hit ratio
2. library cache hit ratio
3. ratio of sorts in memory to disk
The higher the values, the better. If they are low, consider increasing the repective parameters in init.ora. You should be able to find these scripts in the DBA HAndbook.