Re: Support for multi-column aggregate functions

david, these queries get pretty close to wtd.quantile and svyquantile on a 32-record data set. if you have lots of records, i think it'd perform even better? pctiles <- seq( 0 , 1 , .01 ) library(DBI) # load the DBI package (implements the R-database coding) library(MonetDB.R) # load the MonetDB.R package (connects r to a monet database) library(MonetDBLite) # load MonetDBLite package (creates database files in R) db <- dbConnect( MonetDBLite() ) # requires a unique identifier because i could not get row_number() working # https://www.monetdb.org/bugzilla/show_bug.cgi?id=4000 mtcars$id <- seq( nrow( mtcars ) ) # store mtcars dbWriteTable( db , 'mtcars' , mtcars ) sql <- "SELECT t1.id, t1.hp , t1.wt , SUM( t2.wt ) AS cumwt FROM mtcars t1 INNER JOIN mtcars t2 ON t1.hp >= t2.hp GROUP BY t1.id , t1.hp , t1.wt" dbGetQuery( db , sql ) sql2 <- paste("( SELECT row_number() over () AS id , wt , cumwt, totwt, hp FROM mtcars AS td NATURAL JOIN ( " , sql , " ) AS cj , ( SELECT SUM(wt) AS totwt FROM mtcars ) AS tj ) ") dbGetQuery( db , sql2 ) sql3 <- paste( "select pcs.percentile , min(case when cumwt >= totwt * pcs.percentile then hp end) from (" , sql2 , ") AS v , (" , paste( "select" , pctiles , " as percentile" , collapse = " union all " ) , " ) pcs group by pcs.percentile" ) library(Hmisc) library(survey) ms <- svydesign(~1,data=mtcars,weight=~wt) cbind( dbGetQuery( db , sql3 ), wtd.quantile( mtcars$hp , mtcars$wt , pctiles ) , as.numeric(svyquantile(~ hp,ms,pctiles))) On Wed, Apr 27, 2016 at 11:07 AM, Anderson, David B < david.b.anderson@citi.com> wrote:

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@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 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@monetdb.org 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 _______________________________________________ users-list mailing list users-list@monetdb.org https://www.monetdb.org/mailman/listinfo/users-list https://urldefense.proofpoint.com/v2/url?u=https-3A__www.monetdb.org_mailman_listinfo_users-2Dlist&d=BQMFaQ&c=j-EkbjBYwkAB4f8ZbVn1Fw&r=8_GYjk1edsyLJlNaxMxYxBJsviF3JXYvwDK42uy5KWU&m=VPKaqqy1Sox6hJP3RD8x9lYAWs4sDr5tN4jtb0tElwI&s=T43LwaiW3foyJ1zGqAUQo9P1My84NzY92cS5wHK1xeA&e=

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