Hi,

That would be a rather simple project, because it's already
implemented :-) unless, you mean something else with "tree join". What
I meant with "tree join" is nested joins in the form of a tree, for
example:

drop table a;
drop table b;
drop table c;
drop table d;
create table a(x int);
create table b(x int);
create table c(x int);
create table d(x int);
select * from (a inner join b on a.x=b.x) left outer join (c left
outer join d on c.x=d.x) on c.x=a.x;

... and not just as a chain as in:

select * from a inner join b on a.x=b.x left outer join c on c.x=a.x
left outer join d on c.x=d.x;

This was originally not possible, but was eventually implemented. I
forgot to remove it from the list. By the way, it was really tricky to
implement, if you really want to implement a join mechanism (for
example full outer join or merge join) I would probably do that
outside of the database, for example using TreeMaps or (for full outer
joins) by converting SQL statements to other SQL statements (for full
outer join possibly a "union all" or similar).

Regards,
Thomas


On Fri, Mar 23, 2012 at 10:28 AM, Tharindu <[email protected]> wrote:
> Hey All,
>
> We are doing a tree join implementation for the H2 Database as the
> project part for our Final Year Advanced Database Module. This idea
> was specified in the site roadmap. Can anyone of you please direct us
> to the classes that we should refer to get a start to this.
> Thanks in advance.
>
> Regards,
> Tharindu Jayasinghe
>
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