Moving Data from SQLite to PostgreSQL: 4 Easy Steps

Are you looking to move your data from SQLite to PostgreSQL? Well, you’re not the only one! Businesses from all verticals rely heavily on the traditional Relational Database Management model to take care of their transactional data. Now, almost every relational database engines provide its services after you implement them as a server process. This way, programs running on your system can take part in interprocess communication and exchange data. However, the SQLite platform allows your processes to access the database and perform operations directly to Disk File in a serverless manner.

SQLite’s serverless nature coupled with its high-processing speed has made it a popular name in today’s market. SQLite has many advantages but it is considered “light” when it comes to real-world applications. This is the reason, developers seek out PostgreSQL and other RDBMS for heavy tasks like building Web Applications. Moreover, since PostgreSQL is capable of processing tasks concurrently, developers are constantly moving their data from SQLite to PostgreSQL to optimize their workload.

This article will introduce you to the unique features of SQLite & PostgreSQL. Furthermore, we’ll also explore the steps to connect the two and migrate SQLite to PostgreSQL seamlessly!

Now, without much ado, let’s dive in!

What is SQLite?

SQLite is a well-known software library that provides you with an independent, serverless, and easy-to-configure transactional SQL-based database engine. SQLite is an open-source tool and has seen a constant rise in popularity over the years. Moreover, since its source code is publicly available, you can customize it to suit your requirements.

SQLite offers you a zero-configured database. This implies that unlike other databases you don’t have to worry about lengthy configuration tasks to implement SQLite. Furthermore, the SQLite engine is different from standalone processes that you may encounter when using other databases. Therefore, you can link this tool both statically and dynamically as per your requirements.

Key Features of SQLite

The following features give SQLite an edge over other databases:

• Serverless: SQLite operates in a serverless manner and does not need any server process or a system to work.
• Simple & Convenient: SQLite requires no configuration or administration. Moreover, it is a lightweight tool (less than 400KB) and the complete SQLite database can be stored in one single cross-platform disk.
• Self-dependent: SQLite is independent and self-contained and therefore is free from external dependencies. SQLite transactions are also ACID-compliant which provides for safe access from multiple threads.
• Rich Support: SQLite supports features of almost all query languages present in SQL2 standard. Furthermore, SQLite is supported on UNIX OS (Linux, Mac OS-X, iOS, Android) and Windows OS (Win32, WinCE, WinRT).

To learn more about SQLite, visit here.

What is PostgreSQL?

PostgreSQL, one of the most popular RDBMS (Relational Database Management System), was developed in 1996. This open-source platform ensures that you work with high extensibility and SQL compliance databases. Developed by the scholars of the University of California (Berkeley), PostgreSQL is the first choice of businesses because of its property of storing data as structured objects and not as separate documents. Furthermore, you don’t have to be an expert to work with PostgreSQL as it uses the standard SQL syntax and format.

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

Key Features of PostgreSQL

The following features make PostgreSQL a popular RDBMS: 

• Advanced Customization: PostgreSQL provides support for a variety of documents and allows you to customize the data as per your needs. Moreover, the monolithic architecture of PostgreSQL is made of components that rely on automated interaction and offer advanced customization support.
• Compatibility: PostgreSQL is readily compliant with most of the popular operating systems. It also uses multiple fail-safe & backup methodologies to ensure high data reliability.
• Scalability: PostgreSQL can serve your business growth by providing you with an option to scale. However, its scaling amount depends largely on the system (machine) that you will use to run this tool.
• Secure: PostgreSQL has a strong access control mechanism that relies on special security features at the level of rows & columns. Furthermore, this free tool has multi-factor authentication that comes with high-standard certificates and guarantees safe storage for your data.

Our comprehensive guide to PostgreSQL analytics can be a great resource if you’re keen on working with it.

Steps for Connecting SQLite to PostgreSQL

Since you have understood the features, working and differences of PostgreSQL and SQLite, it’s time to learn the process of connecting them. The following steps will help you in connecting SQLite to Postgres using the Fixture method:

• Step 1: Create SQLite DB Dumpdata Backup
• Step 2: Generate a Postgres DB and User
• Step 3: Configure Settings.py
• Step 4: Import Required Fixture via Loaddata from SQLite to PostgreSQL

Step 1: Create SQLite DB Dumpdata Backup

python manage.py dumpdata > whole.json

You can also use the modified version of the above command by including natural primary & foreign keys as follows:

python manage.py dumpdata — natural-foreign — natural-primary > whole.json

It will generate the SQLite dump data in the JSON fixture format. It is suggested that you use this alternate command only if you face any error in restoring (loaddata) data to PostgreSQL.

Step 2: Generate a Postgres DB and User

Now, you have to install Postgres in your system’s operating system. Once that is in place, use the below command to log into it:

sudo su — postgres

psql

Next, generate a PostgreSQL database and create a new user. Provide the user with a password and grant it the required database permission:

create user john;create database nw_db;alter role hero with password ‘new_db@123’;grant all privileges on database new_db to john;alter database new_db owner to john;

Now, to connect SQLite to PostgreSQL you need to configure the Setttings.py tool.

Step 3: Configure Settings.py

In your system, write the following commands:

# install this package 
pip install psycopg2
settings.py
DATABASES = {
‘default’: {
‘ENGINE’: ‘django.db.backends.postgresql_psycopg2’,
‘NAME’: ‘new_db’,
‘USER’ : ‘john’,
‘PASSWORD’ : ‘new_db@123’,
‘HOST’ : ‘localhost’,
‘PORT’ : ‘5452’,
}
}

Next, delete all migration files and create a new migration file for each application. The following command will allow you to delete the old migration files:

find . -path “*/migrations/*.py” -not -name “__init__.py” -delete
find . -path “*/migrations/*.pyc” -delete
do
python manage.py makemigrations
python manage.py migrate

Also, delete the content types (mandatory steps) to avoid numerous errors as follows:

python manage.py shell
from django.contrib.contenttypes.models import ContentType
ContentType.objects.all().delete()

This step completes the task of developing an empty Postgres database. Now, you have to load data into the PostgreSQL database from fixtures.

Step 4: Import Required Fixture via Loaddata from SQLite to PostgreSQL

The final main step to connect SQLite to PostgreSQL requires you to disable every signal present in projects. This will safeguard you from getting unique prebuilt constraints. Finally, use the following command and load data to PostgreSQL database from fixtures:

python manage.py loaddata fixture/whole.json

With this step, you have moved data successfully from SQLite to PostgreSQL via fixtures.

Best Practices to Migrate from SQLite to Postgres

Since, you now know the steps required to connect SQLite to PostgreSQL, keep in mind the following practices while implementing the above method:

• In case you wish to use groups and permissions for moving data from SQLite to PostgreSQL, create a data dump without excluding the types (content) & permissions. This way, you can avoid errors while using the loaddata command as groups heavily rely on permissions.
• Always use SQLite for development only and perform the SQLite to PostgreSQL data transfer in the early stages of your projects. This is because the above-mentioned fixture method to connect SQLite to PostgreSQL operates on massive RAM for loading data. This means, if your SQLite holds more than 100MB of data, the method may falter.
• You might have to change the char field of your model to max_length size. This is to ensure that you are not stumped by the error caused by dumpdata command which sometimes creates space in charfield value. This way you will avoid errors like “in the model, field varying length 30 exceeds 30” while using loaddata command to connect SQLite to PostgreSQL.

Conclusion

This article introduced you to SQLite and PostgreSQL along with their key features. It also explained the 4 easy steps using which you can connect SQLite to PostgreSQL via Fixture. The blog also elaborated on the best practices that you can adopt while implementing the above method on your own. 

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PostgreSQL is a great tool for storing your business data. However, at times, you need to transfer this data from multiple sources to your PostgreSQL account for further analysis. For instance, besides migrating data from SQLite, businesses also migrate their data from MySQL to PostgreSQL. Building an in-house solution for this process could be an expensive and time-consuming task.

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Share your views on connecting SQLite to PostgreSQL in the comments section!