Dears,

Thanks for your reply, appreciated.

Could you please find my inquiries and practical case i encountered below, and clarify it:

As mentioned in document that i read and find also in attached link for your response:

"
13.5.3 Determining When to Use Force Full Database Caching Mode
To improve database performance for table scans and LOB data access, especially for workloads that are limited by I/O throughput or response time, consider using force full database caching mode whenever the size of the database buffer cache is greater than the size of the database.

Consider using force full database caching mode in the following situations:

The logical database size (or actual used space) is smaller than the individual buffer cache of each database instance in an Oracle RAC environment. This is applicable for non-Oracle RAC database as well.

1. The logical database size is smaller than 80% of the combined buffer cache sizes of all the database instances for well-partitioned workloads (by instance access) in an Oracle RAC environment.

2. The database uses SGA_TARGET or MEMORY_TARGET.

3. The NOCACHE LOBs need to be cached. The NOCACHE LOBs are never cached unless force full database caching is used.
"

What I did:

- I ran 52 queries related to some business with no Force Full Database caching, and i got 37 sec as elapsed time. And i monitor Physical and Logical reads using:

select name,value
from v$mystat natural join v$statname
where name in ('physical reads',
'physical reads direct','session logical reads');

and i got physical reads after execution query twice or more.

After that, I set Force Full Database Caching parameter to True, with the following parameter values:
db_cache_size=12000m
sga_target=18000m
memory_target=20000m

and the whole size of Database is 11000m.

I ran same query again, first time i had Physical reads and with elapsed time 38 sec.

I ran queries again with 0 physical reads, But, the same elapsed time.

Please advise regarding that. and if you clarify the 3 points mentioned in paragraph.

Excuse me a second question,,,

What is the best solution especially in 12c to get very small response time:
- Full Database caching
- In-memory
- Using Solid Disks

Thanks in advance, and appreciate your response.

Regards,