Re: Explain Plan question...

[Quoted] The EXPLAIN PLAN output is discussed in the Oracle Application Developers [Quoted] Guide and in many performance tuning books. Basically you should read it [Quoted] inside out, so the most-indented steps are executed first. One thing obvious from the plan, is you don't give your primary key constraints a proper name.
A range scan is a scan for a range of keys (so 1 or more), an unique scan is a scan for one particular key.

Hth,
[Quoted] Sybrand Bakker, Oracle DBA

Sean <dolans_at_my-deja.com> wrote in message news:8budha$e1e$1_at_nnrp1.deja.com...
> I am using the TOAD software and just found the explain plan item.
> Looks great, but I am having trouble understanding how to interpret the
> results. Is there any documentation or websites that can help point
> this out?
>
> I am curious what I should be looking for. And is a RANGE SCAN better
> or worse than a UNIQUE SCAN?
>
> Thanks,
> Sean
>
> PS I'll put the output below in case anyone would like to comment.
> Thanks again.
>
> SELECT STATEMENT Optimizer=CHOOSE
> SORT (ORDER BY)
> NESTED LOOPS
> NESTED LOOPS
> NESTED LOOPS
> NESTED LOOPS
> NESTED LOOPS
> TABLE ACCESS (BY INDEX ROWID) OF KNOW
> INDEX (RANGE SCAN) OF XIF180KNOW (NON-UNIQUE)
> TABLE ACCESS (BY INDEX ROWID) OF STAT_KNOW_REC
> INDEX (UNIQUE SCAN) OF SYS_C006796 (UNIQUE)
> INDEX (UNIQUE SCAN) OF SYS_C006685 (UNIQUE)
> TABLE ACCESS (BY INDEX ROWID) OF SYSTEM_GRP_USER
> INDEX (RANGE SCAN) OF XIF127SYSTEM_GRP_USER (NON-UNIQUE)
> INDEX (UNIQUE SCAN) OF SYS_C006629 (UNIQUE)
> INDEX (UNIQUE SCAN) OF SYS_C006719 (UNIQUE)
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
Received on Thu Mar 30 2000 - 07:26:21 CEST