Support for multi-column aggregate functions

Panagiotis Koutsourakis kutsurak at monetdbsolutions.com
Wed Apr 27 18:17:51 CEST 2016


Hello David,

You can find documentation on how to create User Defined Functions here:

https://www.monetdb.org/Documentation/Cookbooks/SQLrecipes/UserDefinedFunction

Anderson @ 2016-04-27 17:07 CEST:

> I was hoping to use a native/low level implementation for high performance (my data set is on the order of 2.  It looks like multiple column aggregates are supported (corr & covar) so in theory I could add a new function.
>
> Poking around in the archives, it looks like I need to add a new MAL and link it to a C implementation.
>
> https://www.monetdb.org/pipermail/developers-list/2015-December/004553.html
>
> Are there any examples on how to do this?
>
> From: users-list [mailto:users-list-bounces+david.b.anderson=citi.com at monetdb.org] On Behalf Of Anthony Damico
> Sent: Wednesday, April 27, 2016 9:47 AM
> To: Communication channel for MonetDB users
> Subject: Re: Support for multi-column aggregate functions
>
> possible to translate one of these?
>
> http://stackoverflow.com/questions/16450779/another-approach-to-percentiles<https://urldefense.proofpoint.com/v2/url?u=http-3A__stackoverflow.com_questions_16450779_another-2Dapproach-2Dto-2Dpercentiles&d=BQMFaQ&c=j-EkbjBYwkAB4f8ZbVn1Fw&r=8_GYjk1edsyLJlNaxMxYxBJsviF3JXYvwDK42uy5KWU&m=VPKaqqy1Sox6hJP3RD8x9lYAWs4sDr5tN4jtb0tElwI&s=4T2ole-AWFy74ddKmo_2X7-1Okti6t0SGcrP3Pg1ttw&e=>
>
>
> On Wednesday, April 27, 2016, Anderson, David B <david.b.anderson at citi.com<mailto:david.b.anderson at citi.com>> wrote:
> I am really looking for an implementation of a weighted percentile within a group.
>
> -----Original Message-----
> From: Anderson, David B [ICG-MKTS]
> Sent: Wednesday, April 27, 2016 9:18 AM
> To: users-list at monetdb.org<javascript:;>
> Subject: Support for multi-column aggregate functions
>
> All,
>
> Does the current version of MonetDB support multi-column aggregate functions? I need to create a function which returns the "quantiles" of one column using another column as a weighting. It looks like PostgreSQL supports multi-column aggregates as of 8.2.
>
> I could write an embedded R function to compute this, but want to know if it is even possible to pass in multiple columns.
>
> Thanks,
> Dave
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