Linux DSN Configuration

This section shows how to connect to Couchbase and execute SQL queries from several Linux distributions: Debian-based systems, like Ubuntu, and Red Hat Linux platforms, like Red Hat Enterprise Linux (RHEL), CentOS, and Fedora.

Using a Driver Manager

Before installing the CData ODBC Driver for Couchbase 2016 on Linux, you will need to install a driver manager. ODBC-compliant applications connect to the driver through a driver manager. After you connect, the driver manager loads the driver and passes function calls from the application to the driver. The driver manager also implements some functions for discovering the registered drivers and DSNs. DSNs can be defined for a specific user or system wide.

Installing unixODBC

Precompiled binaries for the unixODBC driver manager are available for many operating systems.

On Debian-based systems like Ubuntu, you can install unixODBC by running the following command as root or with sudo:

apt-get install unixODBC unixODBC-dev

On Red Hat Enterprise Linux, CentOS, and Fedora, you can install unixODBC with YUM or DNF. For example, run the following command as root or with sudo:

yum install unixODBC unixODBC-devel

If binaries are not available for your operating system, you will need to compile unixODBC yourself. Please refer to the unixODBC website for more information about obtaining binaries or compiling unixODBC on your operating system.

Installing the Driver Dependencies

Minimum Linux Versions

Below are the minimum supported versions for Red Hat-based and Debian-based systems:


OS	Min. Version
Ubuntu	11
Debian	7
RHEL	6
CentOS	6
Fedora	13

Required Libraries and Packages

Below are the libraries required by the driver and their corresponding packages:


Debian/Ubuntu Package	RHEL/CentOS/Fedora Package	File
libc6	glibc	linux-vdso.1
libc6	glibc	libm.so.6
libc6	glibc	librt.so.1
libc6	glibc	libdl.so.2
libc6	glibc	libpthread.so.0
libc6	glibc	libc.so.6
libc6	glibc	ld-linux-x86-64.so.2
libstdc++6	libstdc++	libstdc++.so.6
zlib1g	zlib	libz.so.1
libgcc1	libgcc	libgcc_s.so.1

Installing the Packages

You can install the necessary dependencies with the following commands:

Debian/Ubuntu:

apt-get install libc6 libstdc++6 zlib1g libgcc1

RHEL/CentOS/Fedora:
```
yum install glibc libstdc++ zlib libgcc
```

Installing the Driver

You can use standard package management systems to easily and quickly install the driver.

On Debian-based systems, like Ubuntu, you can install the driver by running the following command as root or with sudo:

dpkg -i /path/to/.deb

On systems that support the RPM package format, you can install the driver by running the following command as root or with sudo:

rpm -Uvh /path/to/.rpm

Using the unixODBC Configuration Files

You can determine the location of the configuration files on your system by entering the following command into a terminal:

odbcinst -j

Below is an example of the output of this command:

DRIVERS............: /etc/odbcinst.ini
SYSTEM DATA SOURCES: /etc/odbc.ini
FILE DATA SOURCES..: /etc/ODBCDataSources
USER DATA SOURCES..: /home/myuser/.odbc.ini
SQLULEN Size.......: 8
SQLLEN Size........: 8
SQLSETPOSIROW Size.: 8

The driver installation registers the driver for system-wide use and creates a system DSN with empty values for commonly required properties. Modifying unixODBC's system-wide settings requires elevated permissions; to do so, you can use root or the sudo command.

Configuring a DSN

ODBC data sources are defined in sections in the odbc.ini file.

In addition to the connection properties required to connect to your data source, the Driver property specifies either a driver definition in the odbcinst.ini file or the path to the driver library.

[CData Couchbase Source]
Driver = CData ODBC Driver for Couchbase
Description = My Description
MyConnectionProperty1 = My Value
MyConnectionProperty2 = My Value2

You can list the data sources on your system with the following command:

odbcinst  -q -s

Connecting to Couchbase

To connect using the Login method, set User, Password, and Server to the credentials for the account and the address of the server you want to connect to.

Optionally, set N1QLPort if you are not connecting to the default port, 8093.

Securing Couchbase Connections

You can set UseSSL to negotiate an SSL exchange with the server. This property overrides the default N1SQL port the driver connects to; when UseSSL is set, the driver connects on port 18093 by default.

By default, the driver uses the trusted certificate store configured for the system. You can specify another certificate store with SSLServerCert.

Accessing NoSQL Tables

The driver implements Automatic Schema Discovery that is highly configurable. The following sections outline the driver's defaults and link to ways to further customize.

Flattening Nested JSON

By default, the driver projects columns over the properties of objects. Arrays are returned as JSON strings, by default. You can use the following properties to access array elements, including objects nested in arrays.

FlattenArrays: Set this property to the number of array elements that you want to return as column values. You can also use this property with FlattenObjects to extract the properties of objects nested in arrays.
FlattenObjects: By default, this is true; that is, the properties of objects and nested objects are returned as columns. When you set FlattenArrays, objects nested in the specified array elements are also flattened and returned as columns.

Other mechanisms for accessing nested objects are detailed in NoSQL Database.

Configuring Driver Definitions

The sections of the odbcinst.ini file map a driver name to the driver library. The section begins with the driver name; the Driver property points to the path to the driver library. The driver library is the .so file located by default in /opt/cdata/couchbase/lib. A Description property can also be provided.

You can list the drivers installed on the system with the following command:

odbcinst -q -d

Testing the Connection

You can use isql, included with unixODBC, to execute SQL queries to Couchbase from the command line. When testing the connection, use the -v flag to output any messages from the driver manager and the driver.

isql -v "CData Couchbase Source"