Reading v$librarycache

Question

Dear Forum users,
Could you please explain to me the difference between GETS and PINS in the v$librarycache? I've looked in the documentation, but still not clear about it.
When an sql statement is first entered by the user, it's goes through the following:
1. parse
check syntax + semantic analysis <-- soft parse if it can find this in the LRU library cache and skip the rest of the steps below
hard parse
2. use the optimizer to find the best way to execute the query
3. generate execution plan -- done by row source generator
4. sql execution engine then processe the plan for the sql statement
After this the 'compiled code' is saved in the 'sql area' of the library cache.
So, when we execute the same sql statement again,
we do step 1 (soft parse) of the above and skip the rest as the 'comiled code' is found in the 'sql area' of the cache <-- is this a 'GET' ?
and then it can execute the query and then lock it down (PIN) into the LRU cache for execution. Is LRU cache different to the SQL Area or other namespaces ?
I would really appreciate if someone could help me with the above and clear the confusion in a simple way.
Thanks in advance.

Answer 1

Metalink Note: 43760.1
"V$LIBRARYCACHE" Reference Note
This view contains statistics about library cache performance and activity.
NAMESPACE
The library cache namespace
GETS
The number of times a lock was requested for objects of this namespace
GETHITS
The number of times an object's handle was found in memory
GETHITRATIO
The ratio of GETHITS to GETS
PINS
The number of times a PIN was requested for objects of this namespace
PINHITS
The number of times all of the metadata pieces of the library object were found in memory
PINHITRATIO
The ratio of PINHITS to PINS
RELOADS
Any PIN of an object that is not the first PIN performed since the object handle was created, and which requires loading the object from disk
INVALIDATIONS
The total number of times objects in this namespace were marked invalid because a dependent object was modified
DLM_LOCK_REQUESTS
The number of GET requests lock instance locks
DLM_PIN_REQUESTS
The number of PIN requests lock instance locks
DLM_PIN_RELEASES
The number of release requests PIN instance locks
DLM_INVALIDATION_REQUESTS
The number of GET requests for invalidation instance locks
DLM_INVALIDATIONS
The number of invalidation pings received from other instances
Regards,
Reza