That's at least not true for Fb 1.0.2, which I am still using.

I simply did:

select * from rdb$fields f
left join rdb$database d on d.rdb$relation_id = f.rdb$segment_length

and it returned all records in rdb$fields even though many had NULL in
segment_length.

Are you saying that this has changed in Firebird 1.5 and that the above query
would return only those records that had did not have a NULL value in
rdb$fields.rdb$segment_length ???

Set

--- In firebird-support@yahoogroups.com, Jonathan Neve wrote:
> Hi!
>
> I've discovered to my dismay something that you all have probably known
> for a long time: a left outer join only returns a record if the field
> being joined on in the main table is non-null! (Feel free to correct me
> if I've misunderstood something)
>
> 1) Why????
> 2) I found that a full join works... but it's unbearably slow!
>
> Thanks!
> Jonathan Neve.