I have an instance of Cassandra running on my localhost. For this example I have used the default configuration provided in conf\cassandra.yaml
I tried to connect R to Cassandra using the RCassandra package.
Basically, i have just installed the RCassandra package in R and tried to connect.
library("RCassandra")
RC.connect('localhost','9160')
RC.connect('127.0.0.1','9160')
None of those are working. Here is the error I get:
Error in RC.connect("localhost", port = "9160") :
cannot connect to locahost:9160
Using Cassandra-cli with the same parameters work. Can you please help on that.
Thank you
Set start_rpc: true in cassandra.yaml file.
Could not fix it but found a way to make it work: initiate a jdbc connection and then launch RCassandra
#Load RJDBC
library(RJDBC)
#Load in the Cassandra-JDBC diver
cassdrv <- JDBC("org.apache.cassandra.cql.jdbc.CassandraDriver",
list.files("C://Users//aab_ITSolutions//apache-cassandra-1.0.10//lib",pattern="jar$",full.names=T))
#Connect to Cassandra node and Keyspace
casscon <- dbConnect(cassdrv, "jdbc:cassandra://localhost:9160/DEMO")
#Query timeseries data
res <- dbGetQuery(casscon, "select * from StockHist limit 10")
library("RCassandra")
connx = RC.connect('localhost',9160)
Related
Is there a way to write large datasets from R studio to AWS Redshift db directly? I used the following solution that I got online. but it throws error -unused argument: tablename=".."
install.packages('devtools')
devtools::install_github("RcppCore/Rcpp")
devtools::install_github("rstats-db/DBI")
devtools::install_github("rstats-db/RPostgres")
install.packages("aws.s3", repos = c(getOption("repos"), "http://cloudyr.github.io/drat"))
devtools::install_github("sicarul/redshiftTools")
library("aws.s3") library(RPostgres) library(redshiftTools)
pconn_r <- dbConnect(RPostgres::Postgres(), dbname="db",
host='xyz.db.amazon.com', port='1234',
user='user', password='pwd',sslmode='require')
rs_replace_table(tst, dbcon=pconn_r, tableName='abc', bucket="pqr")
Please help!
You can look that library: redshift-r
Or connect throught RJDBC: RJDBC
I am using Cassandra CQL- system in DBeaver database tool. I want to connect this cassandra to R to read data. Unfortunately the connection takes more time (i waited for more than 2 hours) with RCassandra package. but it does not seem to get connected at all and still loading. Does anyone has any idea on this?
the code as follows:
library(RCassandra)
rc <- RC.connect(host ="********", port = 9042)
RC.login(rc, username = "*****", password = "******")
after this step RC.login, it is still loading for more than 2 hours.
I have also tried using RJDBC package like posted here : How to read data from Cassandra with R?.
library(RJDBC)
drv <- JDBC("org.apache.cassandra.cql.jdbc.CassandraDriver",
list.files("C:/Program Files/DBeaver/jre/lib",
pattern="jar$",full.names=T))
But this throws error
Error in .jfindClass(as.character(driverClass)[1]) : class not found
None of the answers are working for me from the above link.I am using latest R version 3.4.0 (2017-04-21) and New version of DBeaver : 4.0.4.
For your first approach, which I am less familiar with, should you not have a line that sets the use of the connection?
such as:
library(RCassandra)
c <- RC.connect(host ="52.0.15.195", port = 9042)
RC.login(c, username = "*****", password = "******")
RC.use(c, "some_db")
Did you check logs that you are not getting some silent error while connecting?
For your second approach, your R program is not seeing a driver in a classpath for Java (JMV).
See this entry for help how to fix it.
library(RJDBC)
cassdrv <- JDBC("org.apache.cassandra.cql.jdbc.CassandraDriver",
list.files("/home/beyhan/Downloads/jars/",pattern="jar$",full.names=T))
casscon <- dbConnect(cassdrv, "jdbc:cassandra://localhost:9042")
Output
> cassdrv <- JDBC("org.apache.cassandra.cql.jdbc.CassandraDriver",
+ list.files("/home/beyhan/Downloads/jars/",pattern="jar$",full.names=T))
> casscon <- dbConnect(cassdrv, "jdbc:cassandra://localhost:9042")
Error in .jcall(drv#jdrv, "Ljava/sql/Connection;", "connect",
as.character(url)[1], : java.lang.NoClassDefFoundError:
org/apache/thrift/transport/TTransportException
Okay, the ODBC Connector is based on the THRIFT Protocol. The THRIFT Connection to Cassandra is deprecated. I think the Python in solution is the best approach for you. Here a example: How to read data from Cassandra with R?
And here is a blog post about Thrift vs. CQL: http://www.datastax.com/dev/blog/cassandra-2-1-now-over-50-faster
Our JDBC Driver for Cassandra allows you to access your Cassandra data in R. To be clear, our driver creates a relational interface to your Cassandra data, allowing you to submit SQL queries to Cassandra through our driver (internally, we translate the SQL to CQL, send the request and return the results as a relational database).
We have an article in our Knowledge Base for connecting, but I'll transcribe it here as well.
Load the RJDBC Package:
library(RJDBC)
Set the driver class and classpath:
driver <- JDBC(driverClass = "cdata.jdbc.cassandra.CassandraDriver", classPath = "MyInstallationDir\lib\cdata.jdbc.cassandra.jar", identifier.quote = "'")
Initialize the JDBC connection:
conn <- dbConnect(driver,"Database=MyCassandraDB;Port=7000;Server=127.0.0.1;")
(Set the Server, Port, and Database connection properties to connect to Cassandra.)
At this point, you can perform standards actions available in R, like:
Listing the tables:
dbListTables(conn)
Executing any SQL query supported by the Cassandra API:
customer <- dbGetQuery(conn,"SELECT City, SUM(TotalDue) FROM Customer GROUP BY City")
Viewing the results:
View(customer)
Feel free to download a free Beta of the driver! If you have any questions, please let us know.
I am trying establish a connection to my redshift database after following the example provided by AWS https://blogs.aws.amazon.com/bigdata/post/Tx1G8828SPGX3PK/Connecting-R-with-Amazon-Redshift. However, I get errors when trying to establish the connection using their recommended driver. However, when I use the Postgre driver I can establish a connection to the redshift DB.
AWS says their driver is "optimized for performance and memory management", so I would rather use it. Can someone please review my code below, and let me know if they see something wrong? I suspect that I am not setting the URL up correctly, but not sure what I should be using instead? Thanks in advance for any help.
#' This code attempts to establish a connection to redshift database. It
#' attempts to establish a connection using the suggested redshift but doesn't
#' work.
## Clear up space and set working directory
#Clear Variables
rm(list=ls(all=TRUE))
gc()
## Libriries for analyis
library(RJDBC)
library(RPostgreSQL)
#Create DBI driver for working with redshift driver directly
# download Amazon Redshift JDBC driver
download.file('http://s3.amazonaws.com/redshift-downloads/drivers/RedshiftJDBC41-1.1.9.1009.jar',
'RedshiftJDBC41-1.1.9.1009.jar')
# connect to Amazon Redshift using specific driver
driver_redshift <- JDBC("com.amazon.redshift.jdbc41.Driver",
"RedshiftJDBC41-1.1.9.1009.jar", identifier.quote="`")
## Using postgre connection that works
#postgre driver
driver_postgre <- dbDriver("PostgreSQL")
#establish connection
conn_postgre <- dbConnect(driver_postgre, host="nhdev.c6htwjfdocsl.us-west-2.redshift.amazonaws.com",
port="5439",dbname="dev",
user="xxxx", password="xxxx")
#list the tables available
tables = dbListTables(conn_postgre)
## Use URL option to establish connection like the example on AWS website
# url <- "<JDBCURL>:<PORT>/<DBNAME>?user=<USER>&password=<PW>
# url <- "jdbc:redshift://demo.ckffhmu2rolb.eu-west-1.redshift.amazonaws.com
# :5439/demo?user=XXX&password=XXX" #useses example from AWS instructions
#url using my redshift database
url <- "jdbc:redshift://nhdev.c6htwjfdocsl.us-west-2.redshift.amazonaws.com
:5439/dev?user=xxxx&password=xxxx"
#attempt connect but gives an error
conn_redshift <- dbConnect(driver_redshift, url)
#gives the following error:
# Error in .jcall(drv#jdrv, "Ljava/sql/Connection;", "connect", as.character(url)[1], :
# java.sql.SQLException: Error message not found: CONN_GENERAL_ERR. Can't find bundle for base name com.amazon.redshift.core.messages, locale en
## Similier to postgre example that works but doesn't work when using redshift specific driver
#gives an error saying url is missing, but I am not sure which url to use?
conn <- dbConnect(driver_redshift, host="nhdev.c6htwjfdocsl.us-west-2.redshift.amazonaws.com",
port="5439",dbname="dev",
user="xxxx", password="xxxx")
# gives the following error:
#Error in .jcall("java/sql/DriverManager", "Ljava/sql/Connection;", "getConnection", :
# argument "url" is missing, with no default
I've done it this way it works for me:
drv <- JDBC("com.amazon.redshift.jdbc41.Driver","PathTO/RedshiftJDBC41-1.1.2.0002.jar")
conn <- dbConnect(drv,"jdbc:redshift://......redshift.amazonaws.com:5439/dev",User,PWD)
The difference I see in yours is that you don't mention the full path to redshift jar in driver_redshift.
Hope it works.
I can not connect to MSSQL using DBI package.
I am trying the way shown in package itself
m <- dbDriver("RODBC") # error
Error: could not find function "RODBC"
# open the connection using user, passsword, etc., as
# specified in the file \file{\$HOME/.my.cnf}
con <- dbConnect(m, dsn="data.source", uid="user", pwd="password"))
Any help appreciated. Thanks
As an update to this question: RStudio have since created the odbc package (or GitHub version here) that handles ODBC connections to a number of databases through DBI. For SQL Server you use:
con <- DBI::dbConnect(odbc::odbc(),
driver = "SQL Server",
server = <serverURL>,
database = <databasename>,
uid = <username>,
pwd = <passwd>)
You can also set a dsn or supply a connection string.
It looks like there used to be a RODBC driver for DBI, but not any more:
http://cran.r-project.org/src/contrib/Archive/DBI.RODBC/
A bit of tweaking has got this to install in a version 3 R but I don't have any ODBC sources to test it on. But m = dbDriver("RODBC") doesn't error.
> m = dbDriver("RODBC")
> m
<ODBCDriver:(29781)>
>
Suggest you ask on the R-sig-db mailing list to maybe find out what happened to this code and/or the author...
Solved.
I used library RODBC. It has great functionality to connect sql and run sql queries in R.
Loading Library:
library(RODBC)
# dbDriver is connection string with userID, database name, password etc.
dbhandle <- odbcDriverConnect(dbDriver)
Running Sql query
sqlQuery(channel=dbhandle, query)
Thats It.