Analyze SFTP Data in R via JDBC

Access SFTP data with pure R script and standard SQL on any machine where R and Java can be installed. You can use the CData JDBC Driver for SFTP and the RJDBC package to work with remote SFTP data in R. By using the CData Driver, you are leveraging a driver written for industry-proven standards to access your data in the popular, open-source R language. This article shows how to use the driver to execute SQL queries to SFTP and visualize SFTP data by calling standard R functions.

Install R

You can match the driver's performance gains from multi-threading and managed code by running the multithreaded Microsoft R Open or by running open R linked with the BLAS/LAPACK libraries. This article uses Microsoft R Open 3.2.3, which is preconfigured to install packages from the Jan. 1, 2016 snapshot of the CRAN repository. This snapshot ensures reproducibility.

Load the RJDBC Package

To use the driver, download the RJDBC package. After installing the RJDBC package, the following line loads the package:

library(RJDBC)

Connect to SFTP as a JDBC Data Source

You will need the following information to connect to SFTP as a JDBC data source:

• Driver Class: Set this to cdata.jdbc.sftp.SFTPDriver
• Classpath: Set this to the location of the driver JAR. By default this is the lib subfolder of the installation folder.

The DBI functions, such as dbConnect and dbSendQuery, provide a unified interface for writing data access code in R. Use the following line to initialize a DBI driver that can make JDBC requests to the CData JDBC Driver for SFTP:

driver <- JDBC(driverClass = "cdata.jdbc.sftp.SFTPDriver", classPath = "MyInstallationDir\lib\cdata.jdbc.sftp.jar", identifier.quote = "'") 

You can now use DBI functions to connect to SFTP and execute SQL queries. Initialize the JDBC connection with the dbConnect function.

SFTP can be used to transfer files to and from SFTP servers using the SFTP Protocol. To connect, specify the RemoteHost;. service uses the User and Password and public key authentication (SSHClientCert). Choose an SSHAuthMode and specify connection values based on your selection.

Set the following connection properties to control the relational view of the file system:

• RemotePath: Set this to the current working directory.
• TableDepth: Set this to control the depth of subfolders to report as views.
• FileRetrievalDepth: Set this to retrieve files recursively and list them in the Root table.

Stored Procedures are available to download files, upload files, and send protocol commands. See gdatamodel for more on using SQL to interact with the server.

Built-in Connection String Designer

For assistance in constructing the JDBC URL, use the connection string designer built into the SFTP JDBC Driver. Either double-click the JAR file or execute the jar file from the command-line.

java -jar cdata.jdbc.sftp.jar

Fill in the connection properties and copy the connection string to the clipboard.

👁 Using the built-in connection string designer to generate a JDBC URL (Salesforce is shown.)

Below is a sample dbConnect call, including a typical JDBC connection string:

conn <- dbConnect(driver,"jdbc:sftp:RemoteHost=MyFTPServer;")

Schema Discovery

The driver models SFTP APIs as relational tables, views, and stored procedures. Use the following line to retrieve the list of tables:

dbListTables(conn)

Execute SQL Queries

You can use the dbGetQuery function to execute any SQL query supported by the SFTP API:

mydirectory <- dbGetQuery(conn,"SELECT Filesize, Filename FROM MyDirectory WHERE FilePath = /documents/doc.txt")

You can view the results in a data viewer window with the following command:

View(mydirectory)

Plot SFTP Data

You can now analyze SFTP data with any of the data visualization packages available in the CRAN repository. You can create simple bar plots with the built-in bar plot function:

par(las=2,ps=10,mar=c(5,15,4,2))
barplot(mydirectory$Filename, main="SFTP MyDirectory", names.arg = mydirectory$Filesize, horiz=TRUE)

👁 A basic bar plot. (Salesforce is shown.)