monetdblite-demo.R

# rm -r /tmp/hmda

install.packages("MonetDBLite")
library(DBI)

dbdir <- "/tmp/hmda"
con <- dbConnect(MonetDBLite::MonetDBLite(), dbdir)

# download at http://homepages.cwi.nl/~hannes/hmda.rds
dd <- readRDS("/tmp/hmda.rds")
str(dd)

system.time(dbWriteTable(con, "hmda_demo", dd))
dbListTables(con)

system.time(print(dbGetQuery(con, "SELECT actiontype, propertytype, loanpurpose, COUNT(*) AS num_records FROM hmda_demo GROUP BY actiontype, propertytype, loanpurpose ORDER BY actiontype, propertytype, loanpurpose LIMIT 10")))

system.time(dd2 <- dbReadTable(con, "hmda_demo"))

library(dplyr)
hmda_src <- MonetDBLite::src_monetdblite(dbdir)
hmda_src
hmda_tbl <- tbl(hmda_src, "hmda_demo")
hmda_tbl

hmda_tbl %>% group_by(actiontype, propertytype, loanpurpose) %>% summarise(num_records = n()) %>% arrange(actiontype, propertytype, loanpurpose) %>% head(10)

quit("no")

# R

library(DBI)
system.time(con <- dbConnect(MonetDBLite::MonetDBLite(), "/tmp/hmda"))
system.time(dd2 <- dbReadTable(con, "hmda_demo"))