Hi Stefan, Okay, I'm trying to write it now. I had a deeper look into the documentation of inner MonetDB structure and a few other questions arise. Is the module LSST somewhere documented? My work will maybe overlap with something already implemented there. Do I understand it correctly, that each module (like the LSST, UDF, ...) has to have the same structure of Makefiles, which are used when building the whole MonetDB source automatically and I don’t need to define them anywhere else? Very important question - I am using 3rd party library (HEALPix C++ library - http://healpix.sourceforge.net/). So I need to write the actual script in C++. Does MonetDB have a problem with that (it is not plain C)? If I provide the Makefiles, the .so file which MonetDB tries to lookup will be just where other .so files from plain C scripts are supposed to be. And what about if I wanted to contribute to the MonetDB source, but that means somehow attaching the C++ library to the sources? It has cca 26K. Thank you very much for answers. Cheers, Jiri

-----Original Message----- From: users-list [mailto:users-list- bounces+nadvornik.ji=gmail.com@monetdb.org] On Behalf Of Stefan Manegold Sent: 27. března 2015 16:54 To: Communication channel for MonetDB users Subject: Re: MonetDB C functions

Hi Jiri,

setp 2 of https://www.monetdb.org/Documentation/Cookbooks/SQLrecipes/UserDe finedFunction points to the source in sql/backends/monet5/UDF, i.e., http://dev.monetdb.org/hg/MonetDB/file/3d1e680be2d9/sql/backends/mo net5/UDF

there, in particular in udf.c, you find examples for both, the scalar and "bulk"/"BAT"/"table" versions of user-defined functions.

Best, Stefan

----- Original Message -----

...

Hi all,

I’m trying to understand the example of user defined functions in MonetDB (

https://www.monetdb.org/Documentation/Cookbooks/SQLrecipes/UserDe fined

...

Function ).

I understand the concept for just reversing a string.

But what about working with tabular data? I’d like to pass to this C function a whole table (list of rows) and then return another table(s)/write result data to other tables.

What is the correct way of doing this? Can I pass some kind of arrays to the C function? Can I return these arrays from a function?

Or is it possible to query the DB directly from the C script?

Thank you very much for some answers.

Best regards,

Jiri Nadvornik

Astronomical Institute AV CR

Stellar department

Czech Republic

nadvornik.ji@gmail.com

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