Introducing SQLite, PostgreSQL and Migration

By Hope Huntley 2 years ago

Businesses across all industries rely heavily on the traditional Relational Database Management model to manage their transactional data. Most relational database engines require implementation as a server process before providing their services, enabling programs running on the system to participate in inter-process communication and data exchange. However, SQLite is a serverless platform that enables processes to access the database and perform operations directly on the Disk File. Its serverless nature and high processing speed have made it a popular choice in today’s market. Nonetheless, developers often turn to PostgreSQL and other RDBMS for heavier tasks, such as building web applications, due to PostgreSQL’s concurrent processing capabilities. As a result, they frequently transfer their SQLite data to PostgreSQL to optimize their workload.

This article introduces SQLite and PostgreSQL and discusses their unique features, as well as providing steps for migrating a database from SQLite to PostgreSQL. SQLite is a well-known software library that provides an independent, serverless, and easily configurable transactional SQL-based database engine. It is an open-source tool that has seen a constant rise in popularity over the years, and its source code is publicly available for customization to meet specific requirements.

One of SQLite’s advantages is extremely easy setup routine. Unlike other DBMS, it does not require implementing tedious configuration tasks. Additionally, the SQLite engine differs from standalone processes that you may encounter when using other databases, allowing you to link the tool both statically and dynamically based on your needs.

Some key features of SQLite include:

  • Serverless operation
  • Simple and convenient usage
  • Self-dependent and independent
  • Rich support for almost all query languages present in SQL2 standard
  • Works on all modern OS (Linux, Mac OS-X, iOS, Android and Windows)

PostgreSQL, one of the most popular RDBMS platforms, was developed in 1996. This open-source platform is highly extensible and SQL compliant, making it an excellent choice for businesses. Developed by the scholars of the University of California (Berkeley), PostgreSQL stores data as structured objects, rather than separate documents, making it a preferred option for many businesses. Additionally, it uses standard SQL syntax and format, making it accessible to anyone without the need for extensive expertise.

You can leverage PostgreSQL to implement queries (relational and non-relational) on both JSON and SQL data, allowing you to rely on SQL commands to access and modify data present in database server tables. This platform uses a monolithic architecture and is programmed using C language to be hardware-friendly. Its vast community support and rich set of functionalities have allowed it to generate applications in sectors like healthcare and banking.

Some key features of PostgreSQL include:

  • Advanced customization support
  • Compatibility with most popular operating systems
  • Scalability to accommodate business growth
  • Strong access control mechanisms with special security features
  • Multi-factor authentication for high-standard certificates and secure data storage

To migrate from SQLite to PostgreSQL, you can use the Fixture method. First, create a backup of the source database using the SQLite command-line tool:

python manage.py dumpdata > whole.json

Convert that backup into a PostgreSQL-compatible format using the pgloader tool. Next step of preparing the target environment before actual migration is to create a new PostgreSQL database and user (when it is necessary):

create user myuser;

create database mydb;

alter role hero with password ‘mydb@host’;

grant all privileges on database mydb to myuser;

alter database mydb owner to myuser;

Finally, load the converted data into the new PostgreSQL database through psycopg2 extension of python as follows:

pip install psycopg2 

settings.py 

DATABASES = { ‘default’: 

{ ‘ENGINE’: ‘django.db.backends.postgresql_psycopg2’, 

‘NAME’: ‘mydb’, 

‘USER’ : ‘myuser’, 

‘PASSWORD’ : ‘mydb@host’, 

‘HOST’ : ‘localhost’, 

‘PORT’ : ‘5452’, 

} }

python manage.py loaddata fixture/whole.json

Do not forget to verify the data in the new database matches the original SQLite database. The approach specified above may seem too complicated, especially if migration project includes multiple SQLite databases. For these cases experiences users choose to work with special database migration tools that are able to automate the process via a user-friendly interface. 

Such automation capabilities are provided by SQLite to PostgreSQL converter, a software product that can migrate schemas, data, indexes and constraints from SQLite database to PostgreSQL or its cloud variations such as Heroku, Azure and Amazon RDS. Because of its direct connection to the source and destination databases, the program achieves high performance without using any middleware software such as ODBC. Additionally, that SQLite to PostgreSQL converter offers command line support, which enables users to script, automate, and schedule the conversion process.