Kjell,

In our shop we are using Firebird 2.5x for Data warehouse and Postgresql 10.x for other projects.

Below is my list of Pros and Cons between the two.  The list below is my experience with the two products.

PostgreSQL over Firebird 2.5

Pros

• Table Partitions are available
• Matierialized Views
• Json & Jsonb support
• Various aggregation functions available
• Different Indexing (gist, gin )
• No 31 character object or column name limits
• Many foreign data wrappers available
• Bulk copy support, even in .NET framework using NPGSQL client library
• Works with EF Core 2.x
• Can be used as a Document DB (NoSQL) using the MARTEN .NET data provider.
• Schemas available
• You can use CitusData or other products to turn your DB into a Distributive DB
• Postgresql is available in the Azure and AWS offerings.
• Parallel Queries are available in PostgreSQL 10 and up.
• Window functions available
• You have Row Level Security ( although I think FB3.x has this also)

Cons

• You can save functions(stored procedures) with invalid syntax which will be made aware at runtime only.
• You can’t re-order the columns in a table once they have been added.
• Not offered as an Embedded DB.
• The Procedural Language is not as straight forward as Firebird’s
• The Server’s directory structure for the Databases is something I need getting accustomed to. I don’t a DB can be easily transferred using OS Copy.

Firebird 2.5 over PostgreSQL

Pros

• Procedural Language is easier to work with (IMHO).
• Triggers are easier to implement, to me (granted I have had limited experience with triggers in PostgreSQL).
• Can re-position column order in a table without having to re-create the table.
• Can be used as an embedded DB.
• A Database is a single file on Disk, you can copy it to another Server and start using it.

Cons

• No Bulk Copy support
• EF Core doesn’t work with Firebird 2.1