SQLite is an efficient and self-contained SQL relational database engine. It is designed with economy, efficiency, independence, and simplicity in mind, making it an ideal choice for local data storage in individual applications and devices. However, unlike more advanced database management systems, SQLite does not support a client/server model, making it unsuitable for shared enterprise data repositories.
Due to these limitations, many companies consider migrating their databases to more robust and powerful DBMS options. One such alternative is PostgreSQL, which offers several essential benefits over SQLite:
- PostgreSQL is a sophisticated object-relational DBMS that supports a wide range of database features such as subselects, transactions, and user-defined types.
- It is highly scalable and reliable, making it suitable for large-scale applications.
- PostgreSQL is an open-source database system, providing cost-effectiveness and the advantage of being open to community contributions.
- The BOOLEAN type in both SQLite and PostgreSQL uses a similar syntax, with ‘t’ representing TRUE and ‘f’ representing FALSE, unlike other popular DBMS.
The process of migrating a database from SQLite to PostgreSQL is generally easier compared to migrations between other DBMS options. Since SQLite databases primarily serve as data storage without stored procedures or complex database objects, the migration process is simplified. However, when dealing with a large number of SQLite tables, the task can become complicated and tedious due to various challenges, such as:
- Converting BLOB types to BYTEA in PostgreSQL.
- Handling differences in string escaping within INSERT INTO clauses.
- Converting autoincrement columns to serial columns.
- Adapting datetime types to timestamp types.
In such cases, specialized tools can be valuable in automating the SQLite to PostgreSQL migration process.
There are different techniques available for migrating from SQLite to PostgreSQL.
- Migrating data through CSV format: One straightforward approach is to export the SQLite database to an intermediate Comma Separated Values (CSV) format and then import it into PostgreSQL. SQLite databases can be exported to CSV format using the following steps:
sqlite> .headers on
sqlite> .mode csv
sqlite> .output data.csv
sqlite> SELECT * FROM customers;
sqlite> .quit
Once these statements are executed, the specified columns of the ‘customers’ table will be exported to a file named ‘data.csv’.
For the next step of the migration process, you can utilize the free pgloader tool available at http://pgloader.io. To load the CSV data into a PostgreSQL database using pgloader, you need to provide certain details about the operation. Here is an example of how it can be done:
LOAD CSV
FROM ‘path/to/file.csv’ (x, y, a, b, c, d)
INTO postgresql:///pgloader?csv (a, b, d, c)
WITH truncate,
skip header = 1,
fields optionally enclosed by ‘”‘,
fields escaped by double-quote,
fields terminated by ‘,’
SET client_encoding to ‘latin1’,
work_mem to ’12MB’,
standard_conforming_strings to ‘on’
BEFORE LOAD DO
$$ drop table if exists csv; $$,
$$ create table csv (
a bigint,
b bigint,
c char(2),
d text
);
$$;
In addition to the aforementioned post-processing steps, there are often additional requirements when migrating SQLite data that includes non-ANSI national symbols and is not saved in Unicode code page. In such cases, the database migration specialist will need to perform the necessary character set conversion using a specialized script or program. These additional steps ensure the proper handling of character encoding during the SQLite to PostgreSQL migration.
2) Commercial software solutions are available that can facilitate a seamless migration from SQLite to PostgreSQL with just a few clicks. One such solution is the SQLite to PostgreSQL converter offered by Intelligent Converters. This software provides all the necessary functionality for an efficient and successful conversion process:
- Compatibility: The converter supports all versions of Linux/Unix and Windows PostgreSQL servers, ensuring compatibility across different platforms.
- Customization: There is an option to modify the resulting table structure during the conversion, allowing for customization according to specific requirements.
- Indexes and Relationships: The converter is capable of converting indexes and relationships between tables, preserving the integrity of the database structure.
- Profile Saving: Conversion settings can be saved into a profile for future use, making it convenient to repeat the conversion process or apply the same settings to different databases.
- Data Merging: There is an option to merge SQLite data into an existing PostgreSQL database, facilitating the integration of SQLite data into an established PostgreSQL environment.
- Data Synchronization: The converter also provides the ability to synchronize a PostgreSQL database with SQLite data, ensuring that the two databases are kept up to date.
- Multibyte Character Set Support: It supports multibyte character sets, allowing for accurate handling of diverse character encodings.
- Script File Export: There is an option to export the SQLite database into a PostgreSQL script file, providing flexibility in terms of how the data is transferred.
- Command Line Support: The converter offers command line support, allowing for automation and integration with other scripts or processes.
These features collectively make the SQLite to PostgreSQL converter a comprehensive and versatile tool for efficient database migration.
