PostgreSQL is advanced open-source database management system providing extremely rich set of features and capabilities. However, for certain projects, the complexity of PostgreSQL can be overwhelming. In such cases, organizations may choose to transfer their database to a different DBMS that is more user-friendly and easier to maintain. One such alternative is SQL Server, which offers a simpler interface and can help reduce the cost of database maintenance.
Migrating a database from PostgreSQL to MS SQL is usually implemented according to extract-transform-load (ETL) method that includes several steps. The first step is to create empty MS SQL database that will be target of the migration. Then export the definitions of PostgreSQL tables and related constraints in form of CREATE-statements. These statements are converted into MS SQL format and then imported into the target database. Next, PostgreSQL data is exported into INSERT-statements complied with ANSI SQL standard, which are then converted into MS SQL dialect and loaded into the target database.
To generate a data definition language script for PostgreSQL table definitions, the pg_dump command is used with specific options such as –schema-only, –no-owner, and –no-privileges. However, the resulting script requires some modifications before it can be loaded into SQL Server. This involves replacing double quotes with square brackets around object names, removing square brackets around types, substituting PostgreSQL’s default schema “public” with SQL Server’s default schema “dbo”, replacing all occurrences of PostgreSQL’s “SERIAL” type with SQL Server’s equivalent “INT IDENTITY(…)”, converting all unsupported data types into text form, and replacing the PostgreSQL query terminator “;” with the MS SQL “GO”.
To export PostgreSQL data as INSERT-statements, the pg_dump command can be utilized with options such as –data-only and –column-inserts. Alternatively, Integration Services can be used as another option to migrate a PostgreSQL database to SQL Server. This option requires creating a new Integration Services project in the SQL Server Business Intelligence Development Studio and then launching a data flow task by double-clicking on the corresponding menu item.
To avoid the manual work according the steps specified above and eliminate the risk of data loss or corruption associated with the human factor, special database conversion tools can be used. PostgreSQL to SQL Server converter is one such tool that supports all versions of PostgreSQL and Microsoft SQL, including Heroku and Azure SQL. It converts indexes with all necessary attributes, offers an option to merge PostgreSQL data into an existing MS SQL table, supports command-line, stores conversion settings into a profile, and provides Unicode support.
To simplify and fully automate tedious process of PostgreSQL to MS SQL database migration (especially for large and complex databases), the conversion tool provides easy-to-use intuitive graphic interface. It does not require any special technical skills from users and guides through the entire migration process in the step-by-step wizard style.
On the first step user has to select migration scenario: either transfer database to SQL Server directly or export it into T-SQL script file (this option is suitable for those situations when the target database server does not allow remote connections).
On the second step user should provide all necessary information to establish connection to PostgreSQL server.
If user selected ‘Migrate to MS SQL server directly’ option on the first wizard page, on the next step he has to provide all necessary information to connect MS SQL server.
On the next step source and destination database must be specified as well as log file (or leave it blank to disable logging). If user specified name of existing MS SQL database, the program will ask how to process it: overwrite entire database, overwrite existing tables, skip existing tables, merge or synchronize.
Next step is dedicated to customizing the migration via specifying PostgreSQL schema and some generic migration settings.
On the next step user has to select tables to migrate. He can also double-click on selected table name to edit it: modify name, type and attributes of every column as well as exclude some of them from migration.
Finally, the database migration is ready to fly and next wizard page indicates progress of the migration procedure.
In conclusion, PostgreSQL is a powerful database management system that may not be suitable for all projects. In such cases, organizations may choose to migrate their database to a more user-friendly and cost-effective DBMS such as SQL Server. The process of database migration involves several steps, but it can be made more efficient and less risky by using a specialized database conversion tool such as PostgreSQL to SQL Server converter.
