db_vndr <- "postgresql"     # e.g. postgresql, mssql, oracle
db_host <- "localhost"      # name or ip address
db_port <- 15432
db_user <- "reader"
db_pass <- "reader"
db_name <- "prod"

if (!require("RPostgreSQL")) install.packages('RPostgreSQL')
if (!require("ggplot2")) install.packages('ggplot2')
if (!require("rmarkdown")) install.packages('rmarkdown')
# pandoc may need to be installed, either from source or packaged releases on github (in case of mac osx)
#if (!require("dplyr")) install.packages("dplyr")
#if (!require("tidyr")) install.packages("tidyr")

# Establish tunnel to database
# ssh -N -L localhost:15432:omop.test.com:5432 user1@proxy.test.com

drv <- dbDriver("PostgreSQL")
con <- dbConnect(drv, dbname = db_name, host = db_host, port = db_port, user = db_user, password = db_pass)

rs <- dbGetQuery(con, "
select count(*),
  to_date(extract(year from visit_start_date) || '-'  || extract(month from visit_start_date) || '-01', 'YYYY-MM-DD') as visit_start_date_1st
from boise.visit_occurrence
group by visit_start_date_1st
order by visit_start_date_1st;
")

plot(count ~ visit_start_date_1st, data=subset(rs, count > 10000))