Access Elasticsearch Data as a Remote Oracle Database

Use the Oracle ODBC Gateway and Heterogeneous Services technology to access Elasticsearch data from your Oracle system.

The Oracle Database Gateway for ODBC and Heterogeneous Services technology enable you to connect to ODBC data sources as remote Oracle databases. This article shows how to use the CData ODBC Driver for Elasticsearch to create a database link from Elasticsearch to Oracle and to query Elasticsearch data through the SQL*Plus tool. You can also create the database link and execute queries from SQL Developer.

About Elasticsearch Data Integration

Accessing and integrating live data from Elasticsearch has never been easier with CData. Customers rely on CData connectivity to:

Access both the SQL endpoints and REST endpoints, optimizing connectivity and offering more options when it comes to reading and writing Elasticsearch data.
Connect to virtually every Elasticsearch instance starting with v2.2 and Open Source Elasticsearch subscriptions.
Always receive a relevance score for the query results without explicitly requiring the SCORE() function, simplifying access from 3rd party tools and easily seeing how the query results rank in text relevance.
Search through multiple indices, relying on Elasticsearch to manage and process the query and results instead of the client machine.

Users frequently integrate Elasticsearch data with analytics tools such as Crystal Reports, Power BI, and Excel, and leverage our tools to enable a single, federated access layer to all of their data sources, including Elasticsearch.

For more information on CData's Elasticsearch solutions, check out our Knowledge Base article: CData Elasticsearch Driver Features & Differentiators.

Getting Started

Connect to Elasticsearch as an ODBC Data Source

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

Set the Server and Port connection properties to connect. To authenticate, set the User and Password properties, PKI (public key infrastructure) properties, or both. To use PKI, set the SSLClientCert, SSLClientCertType, SSLClientCertSubject, and SSLClientCertPassword properties.

The data provider uses X-Pack Security for TLS/SSL and authentication. To connect over TLS/SSL, prefix the Server value with 'https://'. Note: TLS/SSL and client authentication must be enabled on X-Pack to use PKI.

Once the data provider is connected, X-Pack will then perform user authentication and grant role permissions based on the realms you have configured.

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.

Note: If you need to modify the DSN or create other Elasticsearch DSNs, you must use a system DSN and the bitness of the DSN must match your Oracle system. You can access and create 32-bit DSNs on a 64-bit system by opening the 32-bit ODBC Data Source Administrator from C:\Windows\SysWOW64\odbcad32.exe.

Linux

If you are installing the CData ODBC Driver for Elasticsearch 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 Elasticsearch Source]
Driver = CData ODBC Driver for Elasticsearch
Description = My Description
Server = 127.0.0.1
Port = 9200
User = admin
Password = 123456

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

Set Connection Properties for Compatibility with Oracle

The driver provides several connection properties that streamline accessing Elasticsearch data just as you would an Oracle database. Set the following properties when working with Elasticsearch data in SQL*Plus and SQL Developer. For compatibility with Oracle, you will need to set the following connection properties, in addition to authentication and other required connection properties.

MapToWVarchar=False

Set this property to map string data types to SQL_VARCHAR instead of SQL_WVARCHAR. By default, the driver uses SQL_WVARCHAR to accommodate various international character sets. You can use this property to avoid the ORA-28528 Heterogeneous Services data type conversion error when the Unicode type is returned.
MaximumColumnSize=4000

Set this property to restrict the maximum column size to 4000 characters.
IncludeDualTable=True

Set this property to mock the Oracle DUAL table. SQL Developer uses this table to test the connection.

Linux Configuration

In Linux environments, Oracle uses UTF-8 to communicate with the unixODBC Driver manager, whereas the default driver encoding is UTF-16. To resolve this, open the file /opt/cdata/cdata-driver-for-elasticsearch/lib/cdata.odbc.elasticsearch.ini in a text editor and set the encoding.

cdata.odbc.elasticsearch.ini


[Driver]
DriverManagerEncoding = UTF-8

Configure the ODBC Gateway, Oracle Net, and Oracle Database

Follow the procedure below to set up an ODBC gateway to Elasticsearch data that enables you to query live Elasticsearch data as an Oracle database.

Create the file initmyelasticsearchdb.ora in the folder oracle-home-directory/hs/admin and add the following setting:

initmyelasticsearchdb.ora
HS_FDS_CONNECT_INFO = "CData Elasticsearch Sys"
Add an entry to the listener.ora file. This file is located in oracle-home-directory/NETWORK/admin.
If you are using the Database Gateway for ODBC, your listener.ora needs to have a SID_LIST_LISTENER entry that resembles the following:

listener.ora
SID_LIST_LISTENER = (SID_LIST = (SID_DESC = (SID_NAME = myelasticsearchdb) (ORACLE_HOME = your-oracle-home) (PROGRAM = dg4odbc) ) )
If you are using Heterogeneous Services, your listener.ora needs to have a SID_LIST_LISTENER entry that resembles the following:

listener.ora
SID_LIST_LISTENER = (SID_LIST = (SID_DESC = (SID_NAME = myelasticsearchdb) (ORACLE_HOME = your-oracle-home) (PROGRAM = hsodbc) ) )
Add the connect descriptor below in tnsnames.ora, located in oracle-home-directory/NETWORK/admin:

tnsnames.ora
myelasticsearchdb = (DESCRIPTION= (ADDRESS=(PROTOCOL=tcp)(HOST=localhost)(PORT=1521)) (CONNECT_DATA=(SID=myelasticsearchdb)) (HS=OK) )
Restart the listener.
Test the configuration with the following command:
tnsping myelasticsearchdb
Open SQL*Plus and create the database link with the command below:
CREATE DATABASE LINK myelasticsearchdb CONNECT TO "user" IDENTIFIED BY "password" USING 'myelasticsearchdb';

You can now execute queries in SQL*Plus like the one below (note the double quotation marks around the table name):


SELECT * from "Orders"@myelasticsearchdb WHERE ShipCity = 'New York';

Ready to get started?

Download a free trial of the Elasticsearch ODBC Driver to get started:

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Learn more:

Elasticsearch ODBC Driver

The Elasticsearch ODBC Driver is a powerful tool that allows you to connect with live Elasticsearch document databases, directly from any applications that support ODBC connectivity.

Access Elasticsearch like you would a database - read, write, and update through a standard ODBC Driver interface.