Configuration of the ODBC Driver in Linux and Other UNIX

The Denodo Platform provides an ODBC driver for Linux, which is based on the ODBC PostgreSQL driver. There is one version for the driver manager unixODBC and one for iODBC.

You have to install the Denodo ODBC driver in the machine where the client application runs. To do this, follow these steps:

  1. Obtain the appropriate ODBC driver

  2. Install unixODBC

  3. Register the ODBC driver with unixODBC

  4. Register a data source (DSN) that points to Denodo

Obtain the Appropriate ODBC Driver

There are several flavors of the Denodo ODBC driver. This section explains which one you have to select:

  1. Obtain the package denodo-vdp-odbcdriver-linux.zip. To do this:

    1. Copy it from the installation (<DENODO_HOME>/tools/client-drivers/odbc/denodo-vdp-odbcdriver-linux.zip).

    2. Or download it from the ODBC page of the Denodo Community.

      On this page, download the driver for Linux (the name ends up with -linux). Make sure you select a version of the package that is not newer than the Denodo server you are going to connect. For example, if your Denodo server has the update 7.0 20181011, do not download the package denodo-vdp-odbcdriver-7.0-update-20190312-linux because it is newer.

      The section Access Through ODBC explains the policy regarding backward compatibility of this driver.

  2. Extract the contents of the file denodo-vdp-odbcdriver-linux.tar.gz:

    tar -xzf denodo-vdp-odbcdriver-linux.tar.gz --directory /opt
    

    This will create the folder /opt/denodo-vdp-odbcdriver-linux

  3. Choose the appropriate flavor of the driver and copy all its files to the host where the client application runs. The options are:

    • unixodbc_x86: ODBC driver for 32-bit clients and the unixODBC driver manager.

    • unixodbc_x64: ODBC driver for 64-bit clients and the unixODBC driver manager.

    • iodbc_x86: ODBC driver for 32-bit clients and the iODBC driver manager.

    • iodbc_x64: ODBC driver for 64-bit clients and the iODBC driver manager.

    For example, to connect from a 32-bit application using the unixODBC driver manager, copy the folder unixodbc_x86 to the host where the client application runs.

    Denodo also provides the ANSI version of each driver. These are the files ending with “a” (e.g. unixodbc_x86/denodoodbca.so). Only use the ANSI version when the Unicode encoding is not valid for your environment.

Install UnixODBC

Linux does not provide an ODBC driver manager by default; you have to install it. This section explains how to install and configure unixODBC. Denodo also provides the ODBC driver compiled to be used with iODBC.

Important

Install unixODBC and the Denodo ODBC driver on the host where the client application runs.

To verify if unixODBC is installed, execute the following commands. These check if the command line utilities odbcinst and isql are already installed:

which isql

which odbcinst

If both commands return the path to a file, go to the next section.

If unixODBC is not installed, do this:

  1. For Linux distributions that use the RPM packaging system (e.g. Red Hat, CentOS, etc.), execute this:

    sudo yum install unixODBC
    

    For the ones based on Debian like Ubuntu execute this:

    sudo apt-get install unixodbc
    
  2. Execute this to verify that unixODBC was installed correctly:

    odbcinst -j
    

Register the Denodo ODBC Driver in UnixODBC

After installing unixODBC, register the ODBC driver. Follow these steps:

  1. Create a file denodoODBCDriver.template with this content:

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    [DenodoODBCDriver]
    Description=ODBC driver of Denodo
    Driver=/opt/denodo-odbc-driver/unixodbc_x86/denodoodbc.so
    UsageCount=1
    

    Modify line #3 so it points to the flavor of the ODBC driver you want to use (i.e. unixodbc_x86, unixodbc_x64,…).

  2. Execute the following command to register the Denodo driver in the ODBC Driver Manager:

    sudo odbcinst -install -driver -file denodoODBCDriver.template
    

To list the ODBC drivers registered in the driver manager, execute this:

sudo odbcinst -query -driver

The result should list the new driver: DenodoODBCDriver.

To uninstall the driver, execute:

sudo odbcinst -uninstall -driver -name DenodoODBCDriver

Register a Data Source (DSN) on UnixODBC

This section explains how to register a DSN in unixODBC.

  1. Create a file called denodoDSN.template with the content below:

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[Denodo_DSN]
Description = Denodo connection
Driver = DenodoODBCDriver
Servername = <host name>
Port = <Virtual DataPort ODBC port. Default is 9996>
UserName = <Virtual DataPort user name>
Password = <Password>
Database = <Virtual DataPort database>
UserAgent = <name of the application that will use the DSN>
Protocol = 7.4
BoolsAsChar = 0
ByteaAsLongVarBinary= 1
ConnSettings = SET QUERYTIMEOUT TO 3600000; SET I18N TO us_pst; /*krbsrvname=HTTP*/
Debug = 0
Commlog = 0
FakeOidIndex = 0
Fetch = 1000
Ksqo = 0
LFConversion = 1
Optimizer = 0
ReadOnly = 0
RowVersioning = 0
ShowOidColumn = 0
ShowSystemTables = 0
# Uncomment the "Sslmode" property if SSL is enabled in the Virtual DataPort Server
# Sslmode = require
UniqueIndex = 1
UpdatableCursors = 0
UseDeclareFetch = 1
UseServerSidePrepare= 0

In the line #8 (Database), if the name of the database contains non-ASCII characters, they have to be URL-encoded. For example, if the name of the database is “テスト”, set the property to %E3%83%86%E3%82%B9%E3%83%88.

In the line #30 (UseDeclareFetch), if the value is 1, the DSN will use DECLARE CURSOR/FETCH to handle SELECT statements. The effect is that the DSN will retrieve the rows of the result set in blocks, instead of retrieving them all at once. The Fetch property establishes the number of rows of each block. This property is equivalent to the “Fetch size” of the JDBC connections.

In the lines #14 and #15 (Debug and Commlog), if the value is 1, the driver logs detailed ODBC information in files created in the /tmp directory. On a production environment, we strongly recommend setting the value of this property to 0 because logging all the requests impacts the performance of the driver and the log files may grow to a very large size.

In the line #13 (ConnSettings), you can set the properties of the connection established with Virtual DataPort, by adding the following statements:

  1. SET QUERYTIMEOUT TO <value> to change the query time out (value in milliseconds).

  2. SET i18n TO <i18n> to change the i18n of the connection.

For example, to set the default timeout of the queries to one hour, set the value of the property ConnSettings to the following:

ConnSettings=SET QUERYTIMEOUT TO 3600000; SET I18N TO us_pst

Note the ; between each statement.

Read Parameters of the ODBC driver and their default value to learn how these properties work, and their default value.

If you have enabled SSL in the Virtual DataPort server to secure the communications, add the following property to this configuration file:

Sslmode=require
  1. Add the following ConnSettings property to connect to Virtual DataPort using Kerberos authentication:

    /*krbsrvname=HTTP*/
    

    Important

    This line has to be the last thing on the ConnSettings property.

    If Kerberos authentication is enabled on the Denodo database you are connecting to, the driver will ignore the value of the properties “UserName” and “Password”. Instead, it will obtain a Kerberos ticket from the system cache.

    To be able to use Kerberos authentication, the configuration of the DSN has to meet these conditions:

    1. The database that the DSN will connect to is configured with the option “ODBC/ADDO.net authentication type” set to “Kerberos”.

    2. The client has to belong to the Windows domain. The reason is that the ODBC driver uses the ticket cache of the operating system to obtain “ticket-granting ticket” (TGT).

    3. In the property Servername, enter the fully qualified domain name of the Denodo server. That is, if in the Kerberos configuration of the Denodo server the field Server principal is HTTP/denodo-prod.subnet1.contoso.com@CONTOSO.COM, enter denodo-prod.subnet1.contoso.com.

  2. The property UserAgent is optional but we recommend adding it to all the DSNs. That is because the user agent allows you to identify what application opens each connection and the requests that each application sends. This is useful for debugging problems caused by a particular client or for logging purposes.

  1. Execute this to register the new DSN:

sudo odbcinst -install -s -l -f denodoDSN.template

The parameter -l registers the DSN as a “system DSN”. “System DSNs” are available to all the users.

If you do not have enough privileges to register a “system DSN”, replace -l with -h to register the DSN as a “user DSN” instead. If you do this, execute this command with the same user name that you execute the client application that needs to access to this DSN. The reason is that “user DSNs” are only available to the user that registers them.

To list the DSNs registered in the ODBC driver manager, execute this:

sudo odbcinst -query -s

The result should list the new DSN: Denodo_DSN.

  1. Execute this to test the DSN using the command line utility “isql” included with unixODBC:

isql -v Denodo_DSN

You should see something like this:

+---------------------------------------+
| Connected!                            |
|                                       |
| sql-statement                         |
| help [tablename]                      |
| quit                                  |
|                                       |
+---------------------------------------+

Execute any query (for example SELECT 1) and then, type quit to exit this shell.

After setting up the DSN, we recommend reading the section Integration with Third-Party Applications.

Compiling UnixODBC

If you cannot install unixODBC using the package manager of your operating system, download it and compile it. To do this, follow these steps:

  1. Download the latest version of the source code from http://www.unixodbc.org/download.html.

  2. Execute the following commands to extract the source code and compile it:

    tar -zxf unixODBC*.tar.gz
    cd unixODBC
    ./configure.sh
    make
    
  1. Execute the following command:

    sudo make install
    

Troubleshooting Issues

If your application returns an error like this one when trying to use this DSN:

[unixODBC][Driver Manager]Data source name not found, and no default driver specified (0) (SQLDriverConnect)

follow these steps:

  1. Connect to the host where you created the DSN.

  2. Check that these files exist:

    /usr/local/lib64/libodbc.so
    /usr/local/lib64/libodbcinst.so
    

    Or,

    /usr/local/lib/libodbc.so
    /usr/local/lib/libodbcinst.so
    

    Their location may change depending on the Linux/Unix distribution.

  3. Edit the file ~/.bash_profile and add the following at the end:

export LD_PRELOAD=/usr/local/lib/libodbc.so:/usr/local/lib/libodbcinst.so:$LD_PRELOAD

With this change in the value of the variable LD_PRELOAD, you make sure that the application loads the files libodbc.so and libodbcinst.so provided by unixODBC and not the ones provided by other libraries.

Note

If the two files listed above are in lib64 and not in lib, change the line above accordingly.

  1. Logout and login again from this user account. Do this to apply the changes done in the file .bash_profile.