Re: DBA Newbie question

Hi Maurice

Toad is a wonderful tool but it gives you only a tantalizing hint at what possible options for correction are available. Take the statistics gleaned from it to a good Oracle Tuning book and read up all you can on the subject.

What you give in you note is not really enough information. You should always give (Type of Application (e.g. OLTP, DSS etc), Oracle version type and number (e.g. Enterprise Edition and 8.0.6) also whether you are running and of the options (e.g. Partitioning or Replication etc). Also the Host platform Model and Size, with OS type and Version. Oh and is the application a 3rd party package or home grown software.

Having said that the numbers you give would be affected but how long the DB has been up and running. If only 5 minutes would provoke different answers than if it had been running like this for 12 weeks. Of the three items the most notable is the 'Buffer Cache Hit rate', a good rate is in the 90 % range and excellent rate would be in the 98% range depending on the application.

Next question is Why?

Obvious - Is the DB_BUFFER_SIZE too small?

or - Are SQL statements making far too many FULL TABLE SCANS.

are the applications badly written in that they 'charge around the data and deselect what they don't need internal to themselves.

Try having a look at sampling increases in DB_BUFFER_SIZE's with use of DB_BLOCK_LRU_STATISTICS and DB_BLOCK_LRU_EXTENDED_STATISTICS which you will find written up in the Oracle Tuning Guide chapter 14

Trust this helps

Regards

--
Kevin A Lewis (BOCM PAULS LTD) - Animal Feed Manufacturer - Ipswich United
Kingdom)
                        <Kevin_A_Lewis_at_Hotmail.com>

The views expressed herein by the author of this document
are not necessarily those of BOCM PAULS Ltd.
Maurice Sogelée <msogelee_at_kembit.nl> wrote in message
news:8r1ej2$a7gno$1_at_reader4.wxs.nl...


> Hi,

>

> i have been asked to examine a database where users experience problems

> while committing data to a certain table. I have run a trace several

 times,


> but found no severe 'values'.

>

> What i would, using TOAD, is that there are some problem areas, which are

:


>

> - Buffer cashe hit rate= 22,9292 ,  comment : may need to increase

> db_block_buffer

>

> - Chained fetch ratio = 0,0318, comment: pctfree TOO LOW for a table

>

> - parse/execute ratio = 66,9118, comment : high parse to execute ratio.

>

> Can anyone tell me what these statistics tell me ?

>

> regards,

>

> Maurice Sogelée

>

>