SQLite is widely recognized as an open-source Relational Database Management System (RDBMS) with a self-contained engine. It is primarily designed for embedded use within applications or for deployment on mobile devices due to lightweight C library providing access to database files via large subset of SQL statements without the overhead of client-server processes.
However, there are situations where it becomes necessary to replicate or synchronize SQLite data from desktops or mobile devices with a global data warehouse hosted on a corporate Oracle server. As a result, the task of converting SQLite to Oracle has become increasingly common. Despite SQLite’s straightforward nature, the conversion process requires meticulous attention to detail in order to ensure accurate data transfer.
There are few popular approaches to SQLite to Oracle migration:
- SQLitedata is exported into text via .dump command and then loaded into Oracle table using native loader utility like SQL*Loader
- If it is possible to access SQLite via ODBC, use Oracle’s Heterogeneous Service to connect to it via CREATE DATABASE LINK statement
Oracle Database Link and ODBC Driver
Let us consider the second option in details. The approach facilitates access to non-Oracle systems or remote Oracle servers through an ODBC driver. It enables connectivity to any data source compatible with ODBC by utilizing the corresponding ODBC driver installed on the same machine as a gateway. SQLite can be located either on the same machine as the Oracle server or on a separate machine. The gateway can be installed on the machine where SQLite is running, the machine hosting the Oracle database, or it can be installed as a standalone entity on a third machine.
Once the gateway and the SQLite ODBC driver are installed, proceed with creating an initialization file for the Oracle Database Gateway for ODBC. The sample file initdg4odbc.ora can be found in the ORACLE_HOME\hs\admin directory. To create the initialization file for the gateway, make a copy of the sample initialization file and give it a new name. The name should start with “init-” followed by the name of the SQLite data source, such as initSQLite.ora. Each ODBC data source requires its own separate initialization file. After creating the file, configure the HS_FDS_CONNECT_INFO parameter by setting it to the system DSN (Data Source Name) that you created earlier. For example:
HS_FDS_CONNECT_INFO=SQLite
The next step is to configure the Oracle Net Listener to establish communication with the Oracle database. To do this, add gateway details to the listener.ora file, which is located in the ORACLE_HOME\NETWORK\ADMIN directory. Add an entry to the listener.ora file specifying the address on which the Oracle Net Listener should listen:
SID_LIST_LISTENER=
(SID_LIST=
(SID_DESC=
(SID_NAME=SQLite)
(ORACLE_HOME=C:\ORACLE_HOME)
(PROGRAM=dg4odbc)
)
)
The SID of the gateway must be equal in both listener.ora and tnsnames.ora configuration files. Restart the Oracle Net Listener service to apply new settings.
To replicate data from SQLite to Oracle,add a connect descriptor for the gateway to the tnsnames.ora file, which is typically located in the ORACLE_HOME\NETWORK\ADMIN directory. The SID specified in the connect descriptor should match the value defined in the listener.ora file.
After updating the tnsnames.ora file, you can create a database link to access the ODBC data source. This can be done using a database tool such as SQL Developer. Follow these steps:
- Connect to your Oracle database server using the database tool.
- Execute the CREATE DATABASE LINK statement to create the link. Here’s an example:
CREATE DATABASE LINK gateway_link
CONNECT TO gateway_user
IDENTIFIED BY gateway_password
USING ‘gateway_service_name’;
Replace gateway_link with the desired name for the database link, gateway_user and gateway_password with the credentials for accessing the gateway, and gateway_service_name with the appropriate service name for the gateway.
By creating the database link, you establish a connection between the Oracle database and the ODBC data source through the gateway. This allows you to access the ODBC data source from Oracle database and migrate from SQLite to Oracle.
Once you have successfully created the database link, you can verify its creation by refreshing and expanding the connection in the left pane of SQL Developer. The newly created link should be visible under the “Database Links” section.
To execute a query against the ODBC data source using the database link, you can use the following syntax:
SELECT * FROM table_name@database_link;
Replace table_name with the name of the table you want to query, and database_link with the name of the database link you created earlier.
SQLite to Oracle Converter
Both of the methods mentioned above require some prerequisites like creating Oracle table, mapping data types, building indexes and others. For more automated solution it is suggested to review dedicated SQLite to Oracle database converters.
For example, SQLite to Oracle converter developed by Intelligent Converters automatically generates data modeling language (DML) and data definition language (DDL) statements that create required Oracle meta-objects and replicate SQLite data into the target database. The tool analyzes schema, data types and other specific features of the source SQLite database and converts it into Oracle format in the most intelligent way.
Key features of the SQLite to Oracle converter:
- All versions of Oracle are supported including DBaaS services like Amazon RDS
- Table definitions, indexes, constraints and data are migrated
- Options to merge and synchronize existing Oracle tables with SQLite data
- Command line support to script and schedule SQLite to Oracle database migration
