How can I increase my Library Cache Hit Ratio?

Question

I was wondering if anyone can help me out regarding the values that I am getting for my Library Cache hits stats
Half of the samples that I have taken on a periodic interval today have ranged from 89% to 96%.
The SQL that I have used is,
SELECT
sysdate,
SUM(PINS-RELOADS)/SUM(PINS)*100
from v\$librarycache
Also, Running the AWR report for 4am to 4pm, see below
Shared Pool Statistics AWR report
                    Begin      End
Memory Usage %:           50.83      42.43
% SQL with executions>1:      55.56      77.13
% Memory for SQL w/exec>1:      74.12
Regarding the current SGA settings,
SQL> show parameter sga_target;
NAME TYPE VALUE
sga_target big integer 1184M
SQL>
SQL> select pool,name,bytes/1048576 "Size in MB" from v$sgastat where name = 'free memory';
POOL NAME Size in MB
shared pool free memory 135.742641
large pool free memory 15.9389648
java pool free memory 16
The main questions are,
a) is the low Library cache hit ration particularly low?
b) if I want to improve this figure, it is advised that the 'SHARED_POOL_SIZE' parameter should be increased.
Obviously Oracle itself is in charge of this at present, so what can I do to improve?
c) Are there any really good links to help me to understand the figures that appear in the AWR report.

Answer 1

a) is the low Library cache hit ration particularly low?
I didnt understand this.Can you please rephrase?
b)
Well indeed that shared pool controls the allocation and everything about Library Cache but it doesnt mean that increasing the value will stop all the issues.Its among the hardest parameters to be tuned infact for the reason that what primarly comes into it,sql statements,code and all that,that is not written entirely by a dba/tuner.Its by developers who does some times not so good things that are required to make shared pool work properly.Very commonly occuring mistake can be quoted as the lack of use of bind variabls and constant use of literals.In that case,eventualy we will have a hard parse of all the statements which will eat up the shared pool some time or the other.No matter what size it may be,it will end to the same result.Hit ratio is a guiding factor,not the end goal of tuning.Its been documented so many places,here,other forums,even in OU books also that looking and tuning alone the hit ratio may not end up at the expected or right results.You should look for the Parse statistics in the AWR report how they are working.How many are Parse(hard),Parse(total) statistics coming up?What is the sql execute to parse time,elapsed time and the related statistics.They will be helpful in getting things sorted out more nicely and correctly.
I am sure I have missed so much than I said.Surely you will get more better advice on this.Have patience and wait.
b)Documentation will be a good point.Performance tuning in that is a good resource.
http://www.oracle.com/pls/db102/to_toc?pathname=server.102%
2Fb14211%2Ftoc.htm&remark=portal+%28Getting+Started%29
I am not sure about a specific book about AWR but this one is good for over all knowledge about tuning of Oracle.
http://www.mcgraw-hill.co.uk/html/007222729X.html
Aman....