haskelldb-users

[Haskelldb-users] HaskellDB in an industrial environment

[Santoemma E. <enr...@be...>]

Hello,

since some month I'm considering to use the library in a part of a =
project for the market.
I gave up to put it in a previous part of the project, a framework, =
because my users wanted complete control over the sql statements, and =
also because (I believe) HaskellDB doesn't support left/right joins.

But now I'm working on pure combinators of the project's data set, and =
perhaps HaskellDB can show its power.

I ask these three questions:
1) Is the library too young for a real world project? Does it work with =
Oracle (throuhg ODBC)?
2) I'm happy to test the library, but in case of big troubles/doubts is =
it realistic to get feedback from the people behind the software in, =
say, 2-3 days?
3) Where exactly the correction to the DBDirect bug is? The home page =
says that, on Oct 3, there is a bug fixed in cvs. I downloaded DBDirect =
v. 1.12 but I found only minor changes on the error strings.

Almost forgotting: warm congratulation for the great work done!

Enrico

Re: [Haskelldb-users] HaskellDB in an industrial environment

[Bjorn B. <d00...@dt...>]

Santoemma Enrico wrote:
> 1) Is the library too young for a real world project? Does it work
> with Oracle (throuhg ODBC)?

There are still significant bugs in HaskellDB, see the open bugs in
http://sourceforge.net/tracker/?group_id=3D101095&atid=3D629040

Whether it is ready for a real world project depends on the nature of=20
the project I guess. The only way to find out is to test it. I should=20
mention that there is currently no support for things like prepared=20
statements and persistant connections.

HaskellDB works with the HSQL and wxHaskell ODBC interfaces, but as far
as I know, noone has tested HaskellDB with Oracle.

> 2) I'm happy to test the library, but in case of big troubles/doubts
> is it realistic to get feedback from the people behind the software
> in, say, 2-3 days?

At the moment, I seem to be the only person answering questions, and I
can't promise to always be available because of travel and such. I am
also quite bust right now, so I don't have much time for large scale
hacking. I should have time for small fixes, applying patches and
answering questions though.

> 3) Where exactly the correction to the DBDirect bug is? The home page
> says that, on Oct 3, there is a bug fixed in cvs. I downloaded
> DBDirect v. 1.12 but I found only minor changes on the error strings.

As far as I recall, the fix was not in the DBDirect module itself, but
rather in one of the modules it uses.

In general, using the CVS version is probably the best way to go, since
there hasn't been a release for a while.

/Bj=F6rn Bringert

Re: [Haskelldb-users] HaskellDB in an industrial environment

[Frederik E. <fre...@a5...>]

> Santoemma Enrico wrote:
> >1) Is the library too young for a real world project? Does it work
> >with Oracle (throuhg ODBC)?
> 
> There are still significant bugs in HaskellDB, see the open bugs in
> http://sourceforge.net/tracker/?group_id=101095&atid=629040

What's the biggest bug? "No explicit grouping"?

Also, it would be nice to have somewhere -- maybe in the wiki? -- some
examples of SQL queries which can be done and which can't be done in
HaskellDB. I have a program which I've started writing using regular
SQL statements, and I'm wondering if I should translate it to
HaskellDB. Something like this would help me decide. For example here
are some queries, variables with $ represent parameters... (it's a
simple flash card program)

select id from cards where cards.id not in
    (select alg_data.id from alg_data) order by rand() limit 1

select id from alg_data where uid = $uid and
    when_eligible < $vt and
    id like $pat order by curr_delay desc limit 1

select max(show_num) from hist where (uid,id)=($uid,$id)

select min(a.s), avg(a.s), max(a.s), sum(a.s) from 
    (select id,max(show_num) s from hist where 
            uid = $uid and
            id in (select id from alg_data where
                          uid=$uid and when_eligible < $vt)
                   group by id) as a

I guess there must be a lot of benefits to using an embedded language,
I read the paper and it seems like a great idea - but if I couldn't
translate all of these, or get back the same functionality, then it
would be hard to try to port the project, so I'm reluctant to start
without more examples of what can and can't be done (and I imagine
that others are in similar positions). I'm a bit new to SQL, so please
bear with me...

Frederik

P.S. Is there just the tutorial in wiki-form? Why not put the rest of
the documentation on a wiki, so people can add to it?

P.P.S. The test application says "Server error!"...

http://jackass.tekno.chalmers.se/dp03-7/cgi/run

--
Frederik Eaton                         http://ofb.net/~frederik/

Re: [Haskelldb-users] HaskellDB in an industrial environment

[Bjorn B. <d00...@dt...>]

Frederik Eaton wrote:
>>Santoemma Enrico wrote:
>>
>>>1) Is the library too young for a real world project? Does it work
>>>with Oracle (throuhg ODBC)?
>>
>>There are still significant bugs in HaskellDB, see the open bugs in
>>http://sourceforge.net/tracker/?group_id=3D101095&atid=3D629040
>=20
>=20
> What's the biggest bug? "No explicit grouping"?

I'm not sure. AFAIK, there are no bugs which make HaskellDB generally=20
unusable, but different people will have different needs. Actually now=20
tha you mention it "No explicit grouping" feels more like a request for=20
enhancement, which are tracked by the RFE tracker at:

http://sourceforge.net/tracker/?group_id=3D101095&atid=3D629043

The bugs I personally think are the worst are the high priority ones in=20
the bug tracker.


> Also, it would be nice to have somewhere -- maybe in the wiki? -- some
> examples of SQL queries which can be done and which can't be done in
> HaskellDB. I have a program which I've started writing using regular
> SQL statements, and I'm wondering if I should translate it to
> HaskellDB. Something like this would help me decide. For example here
> are some queries, variables with $ represent parameters... (it's a
> simple flash card program)

I don't have time to write the HaskellDB code for you right now, it=20
being Saturday night and all, but see the comments below.

> select id from cards where cards.id not in
>     (select alg_data.id from alg_data) order by rand() limit 1

HaskellDB does not currently support queries in expressions, as needed=20
by the IN operator, see the RFE:
http://sourceforge.net/tracker/index.php?func=3Ddetail&aid=3D961869&group=
_id=3D101095&atid=3D629043

There is also no rand() function, but that can quite easily be added by=20
the used.

> select id from alg_data where uid =3D $uid and
>     when_eligible < $vt and
>     id like $pat order by curr_delay desc limit 1

Should be ok.

> select max(show_num) from hist where (uid,id)=3D($uid,$id)

Seems easy enough.

> select min(a.s), avg(a.s), max(a.s), sum(a.s) from=20
>     (select id,max(show_num) s from hist where=20
>             uid =3D $uid and
>             id in (select id from alg_data where
>                           uid=3D$uid and when_eligible < $vt)
>                    group by id) as a

IN expressions are not supported, see above. This query could be done as=20
a join instead, right? (It's saturday night, you don't expect me to=20
actually think, do you? :-P )

> P.S. Is there just the tutorial in wiki-form? Why not put the rest of
> the documentation on a wiki, so people can add to it?

Good idea! If you move the stuff to the wiki, I'll update the HaskellDB=20
homepage. Assuming there are no objections from anyone?

> P.P.S. The test application says "Server error!"...
>=20
> http://jackass.tekno.chalmers.se/dp03-7/cgi/run

Eh, right. The Chalmers computer support group seems to have changed the=20
installation. I have removed the link from the homepage. Maybe we can=20
put a demo app somewhere else, or link to an existing one. Shae?


/Bj=F6rn

Re: [Haskelldb-users] HaskellDB in an industrial environment

[Shae M. E. <sh...@Sc...>]

Bjorn Bringert <d00...@dt...> writes:

> Good idea! If you move the stuff to the wiki, I'll update the
> HaskellDB homepage. Assuming there are no objections from anyone?

I've moved the HaskellDBTutorial from AvianWiki to HaWiki.
The rest of the docs would also be welcome on HaWiki.

> Eh, right. The Chalmers computer support group seems to have changed
> the installation. I have removed the link from the homepage. Maybe we
> can put a demo app somewhere else, or link to an existing one. Shae?

Sure, is the latest demo app source available somewhere?
I have HaskellDB installed on ScannedInAvian, so it's not a problem.

I hear rumors that HaskellDB will be a Cabal/debian package soon too.
-- 
Shae Matijs Erisson - http://www.ScannedInAvian.com/ - Sockmonster once said:
You could switch out the unicycles for badgers, and the game would be the same.

Re: [Haskelldb-users] HaskellDB in an industrial environment

[Bjorn B. <d00...@dt...>]

Shae Matijs Erisson wrote:
> Bjorn Bringert <d00...@dt...> writes:
>=20
>>Good idea! If you move the stuff to the wiki, I'll update the
>>HaskellDB homepage. Assuming there are no objections from anyone?
>=20
> I've moved the HaskellDBTutorial from AvianWiki to HaWiki.
> The rest of the docs would also be welcome on HaWiki.

Ok, I've changed the tutorial link. Anyone wanna move the other docs?

>>Eh, right. The Chalmers computer support group seems to have changed
>>the installation. I have removed the link from the homepage. Maybe we
>>can put a demo app somewhere else, or link to an existing one. Shae?
>=20
> Sure, is the latest demo app source available somewhere?
> I have HaskellDB installed on ScannedInAvian, so it's not a problem.

I think the DEMO code is available from the homepage, but I don't really=20
know anything about it. Mary, Martin, Torbj=F6rn; any comments?

I was thinking that there might be other demo apps to put up too. There=20
could be a wiki page with links to apps using HaskellDB. Hackage,=20
Curryspondence and BloB off the top of my head, I'm sure there are others=
.

> I hear rumors that HaskellDB will be a Cabal/debian package soon too.

Sweet! Who's working on that?

/Bj=F6rn