Analyze SFTP Data in R via ODBC

Access SFTP data with pure R script and standard SQL. You can use the CData ODBC Driver for SFTP and the RODBC 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 data and visualize SFTP data in R.

Install R

You can complement the driver's performance gains from multi-threading and managed code by running the multithreaded Microsoft R Open or by running R linked with the BLAS/LAPACK libraries. This article uses Microsoft R Open (MRO).

Connect to SFTP as an ODBC Data Source

Information for connecting to SFTP follows, along with different instructions for configuring a DSN in Windows and Linux environments.

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.

When you configure the DSN, you may also want to set the Max Rows connection property. This will limit the number of rows returned, which is especially helpful for improving performance when designing reports and visualizations.

Windows

If you have not already, first specify connection properties in an ODBC DSN (data source name). This is the last step of the driver installation. You can use the Microsoft ODBC Data Source Administrator to create and configure ODBC DSNs.

Linux

If you are installing the CData ODBC Driver for SFTP in a Linux environment, the driver installation predefines a system DSN. You can modify the DSN by editing the system data sources file (/etc/odbc.ini) and defining the required connection properties.

/etc/odbc.ini

[CData SFTP Source]
Driver = CData ODBC Driver for SFTP
Description = My Description
RemoteHost = MyFTPServer

For specific information on using these configuration files, please refer to the help documentation (installed and found online).

Load the RODBC Package

To use the driver, download the RODBC package. In RStudio, click Tools -> Install Packages and enter RODBC in the Packages box.

After installing the RODBC package, the following line loads the package:

library(RODBC)

Note: This article uses RODBC version 1.3-12. Using Microsoft R Open, you can test with the same version, using the checkpoint capabilities of Microsoft's MRAN repository. The checkpoint command enables you to install packages from a snapshot of the CRAN repository, hosted on the MRAN repository. The snapshot taken Jan. 1, 2016 contains version 1.3-12.

library(checkpoint)
checkpoint("2016-01-01")

Connect to SFTP Data as an ODBC Data Source

You can connect to a DSN in R with the following line:

conn <- odbcConnect("CData SFTP Source")

Schema Discovery

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

sqlTables(conn)

Execute SQL Queries

Use the sqlQuery function to execute any SQL query supported by the SFTP API.

mydirectory <- sqlQuery(conn, "SELECT Filesize, Filename FROM MyDirectory WHERE FilePath = /documents/doc.txt", believeNRows=FALSE, rows_at_time=1)

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.)