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Home -> Community -> Mailing Lists -> Oracle-L -> What I'm doing? explanation about my posts
Hi,
I like to write articles, at the same time I investigate something I share
it to other so it could be useful, I did one Tom Kyte check (about
flashback) but he didn't have more time.
I ask Burleston if he would have time, because I saw he likes some
communitary activities, but he neither ansewr my email.
What I'm doing now is posting interesting topics, principally brief, for every one, I am including in an article about basic tuning (bulk collection, null in in() ) I soonly will put in my page on geocities, so based on the feedback to improve,
The idea is a very simple explanation and introduction, but enough clear, so if you want more information you go to tahiti.oracle.com, search and get a copmlete answer.
for example I improved in() explanation
When comparing any value using IN with NULL values, IN don't return TRUE
hence, ignore null values as you can see in the table there are 310 null
values in column TBL_DSM.
SQL> select count(*) from daz.utl_tablas_me
2 where tbl_dsm in
3 (select null from daz.utl_tablas_me);
COUNT(*)
0
SQL> select count(*) from daz.utl_tablas_me
2 where exists(select null from daz.utl_tablas_me);
COUNT(*)
310
A more clear example of this situation you can see in this way
select count(*) from dual where null in (null );
COUNT(*)
0
bulkcollection to ...
During execution, every SQL statement causes a context switch between the two engines. Performance can be improved reducing the number of contexts switches using FORALL for bulk collection to one.
If you don't like you can simply ignore this posts :) Happy Carnaval
-- Archives are at http://www.freelists.org/archives/oracle-l/ FAQ is at http://www.freelists.org/help/fom-serve/cache/1.htmlReceived on Fri Feb 20 2004 - 15:22:06 CST
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