Re: FW: Informix versus Oracle Spatial
Posted in 2005
Superboer showed that Oracle 9.2 accepted multiple NULL rows in a unique index, while Informix 9.30 rejected the second. rkusenet wondered if Oracle does not index nulls, and Superboer said that would force sequential scans for null searches. Noons replied that NULL means unknown so it cannot be a duplicate, and that unique indexes differ from primary keys. Opinions only.
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Topics: SQL Development & Query Writing
Is SQL*Plus: Release 9.2.0.1.0 a Cretaceous or Jurassic version ????
create table nullix( a int, b char(10));
create unique index ixienull on nullix (a);
insert into nullix (b) values ('One ');
insert into nullix (b) values ('One Dupl');
insert into nullix (b) values ('Two Dupl');
select count(*) , a from nullix
group by a
gives back 3 so i get 3 nulls in my table where the index is
unique.....
informix (V 9.30) pukes at the second insert ... duplicate....
if obstacle can't even keep their pants up with normal indices i will
not trust
them at all with exotic things.
you will probably tell me that the above is how it should work...
right??
having multiple null values in a unique index....
Superboer.
DA Morgan schreef:
> Simon wrote:
>
> > You can rebuild them online, but I don't think this is supported by
> > Oracle as it can put a lot of stress on the shared pool which in turn
> > can cause core dumps
>
> Nonsense.
>
> and possibe unforseen/unrequired downtime. The
> > official work around of which is to do the rebuilds offline. I think it
> > is quite a 'buggy' problem, and apparently fixed in later versions of
> > 9i and in 10g.
>
> Also known as the currently supported versions of the product.
>
> Referring back, with any product, to Cretaceous or Jurassic versions
> will always let you criticize. The thigs I could tell you about
> Informix 1.0 ....
> --
> Daniel A. Morgan
> http://www.psoug.org
> damorgan@x.washington.edu
> (replace x with u to respond)
my knowledge about Oracle is minimal.
Could it be because Oracle does not index null values.
"Superboer" <superboer7@planet.nl> wrote in message
news:1133422691.225324.315430@o13g2000cwo.googlegroups.com...
> Is SQL*Plus: Release 9.2.0.1.0 a Cretaceous or Jurassic version ????
>
> create table nullix( a int, b char(10));
> create unique index ixienull on nullix (a);>
> insert into nullix (b) values ('One ');
> insert into nullix (b) values ('One Dupl');
> insert into nullix (b) values ('Two Dupl');>
> select count(*) , a from nullix
> group by a>
> gives back 3 so i get 3 nulls in my table where the index is
> unique.....
> informix (V 9.30) pukes at the second insert ... duplicate....
>
> if obstacle can't even keep their pants up with normal indices i will
> not trust
> them at all with exotic things.
>
> you will probably tell me that the above is how it should work...
> right??
> having multiple null values in a unique index....
>
> Superboer.
>
>
>
> DA Morgan schreef:
>
>> Simon wrote:
>>
>> > You can rebuild them online, but I don't think this is supported by
>> > Oracle as it can put a lot of stress on the shared pool which in turn
>> > can cause core dumps
>>
>> Nonsense.
>>
>> and possibe unforseen/unrequired downtime. The
>> > official work around of which is to do the rebuilds offline. I think it
>> > is quite a 'buggy' problem, and apparently fixed in later versions of
>> > 9i and in 10g.
>>
>> Also known as the currently supported versions of the product.
>>
>> Referring back, with any product, to Cretaceous or Jurassic versions
>> will always let you criticize. The thigs I could tell you about
>> Informix 1.0 ....
>> --
>> Daniel A. Morgan
>> http://www.psoug.org
>> damorgan@x.washington.edu
>> (replace x with u to respond)
>
-- Could it be because Oracle does not index null values. if that is the case then it is at least equally bad.. having a huge table and look for nulls causes a seq scan... YIKES... Superboer.
rkusenet apparently said,on my timestamp of 1/12/2005 10:11 PM: > my knowledge about Oracle is minimal. > > Could it be because Oracle does not index null values. Actually, it can. Quite easily. But it requires reading a manual, something these "geniuses" are alergic to... >> >>you will probably tell me that the above is how it should work... >>right?? >>having multiple null values in a unique index.... >> Absolutely. null is absence of any information about a datum, how can you know that it is a duplicate? It might well not be. You are confusing unique index with primary key index and unique key. There is a difference. Unnoticed in products that don't have a clue what keys are for. But once again, it requires reading a manual... -- Cheers Nuno Souto in stormy Sydney, Australia wizofoz2k@yahoo.com.au.nospam