PgConf.Russia 2020

Migrating engineering software from Oracle to PostgreSQL
Dmitry will talk about using an automated migrator developed by "Diasoft" company for migrating Russian systems to PostgreSQL.
Taking the LOOTSMAN engineering software (developed by the ASKON company), we will speak about the key aspects of migration, review possible issues and ways to resolve them, as well as discuss performance optimization methods for migrated stored procedures.

We will discuss stored procedures and functions, as well as the code within the database in general. We'll take a look at stored procedures from different angles: as a DBA, a database developer, and a backend developer. We will try to understand the specifics of stored procedures that often go against the common coding guidelines, and discuss best practices for working with stored procedures.
This is mainly a motivational talk for database and backend developers, not an advanced tech talk.

In the report, we want to talk about the experience of migrating one large system from Oracle to PostgreSQL. The system itself was built on the PHP + Oracle stack; its distinguishing feature was that all business logic was implemented in PL / SQL code. In a DBMS, there are more than 3000 packages with 4-10 functions (procedures) in each. In PHP - more than 10,000 forms with inserts of anonymous blocks used to receive data, process and save results in Oracle.

To solve this extremely voluminous work, we took ANTLR4 (a powerful parser generator for reading, processing, executing, or translating structured text), PL/SQL grammar, and created an automatic converter that allows you to convert all objects in the schema and our system from Oracle to working code for PostgreSQL.

Recently, I was working on a project where graphQL was used for sending requests to its .NET Core backend, but this was not a good idea. The point is, a graphQL query is a hierarchical structure with a dynamic set of fields. It’s difficult to perform such requests via a statically-typed programming language and a relational database as suggested by the tools available. So, I came up with the idea of using the plv8 extension and perform graphQL queries right on the database side. It took me about two hours to develop a working prototype that could perform the same queries as the software under development for more than one month! Then various improvements have been made and I want to introduce them all. If you are thinking of using graphQL instead of REST, my speech could be most useful and could help you to save a lot of time.