Re: Oracle - sqltuning and statistics

Ann Myhre wrote:

> Hi all,
> In a schoolproject I have been asked to say something about
> statistics in a sql tuning setting for Oracle. But I am
> confused about the word statistics (English is not my first
> language either). It seems that there is two kind of
> statistics, one concering the objects (tables, indexes etc),
> which is really accumulated and fresh information about the
> objects themselves ("If the size and data distribution of
> these tables changes frequently, generate these statistics
> regularly to ensure the statistics accurately represent the
> data in the tables"). And the second kind is more what one
> would think statistics to be in sql tuning , cpu-time, number
> of times a statement has been parsed, executed and fetched,
> total numbers of datablocks read, etc. Is this duality right?
> Have I (mis-)understood? Could anyone comment on this please?
>
> Ann
>
>

        Yes there is a duality, but...

        The first type of statistics is related to tuning the
        underlying database.  (The statistics are used by the
        Cost Based Optimizer to determine which, if any, index
        should be used to satisfy a query.)

        The second type of statistics is related to tuning 
        individual queries.

-- 
Jerry Gitomer
Once I learned how to spell DBA, I became one