How to debug postgresql stored procedures?

Question

I realize that there is nothing similar to SQL Server Management Studio, so I am mentally prepared to use the good old printf debugging.

The only question is how to do "printf" from a stored procedure?

Solution 1

To "print" a message, you can use raise notice from within a PL/pgSQL function:
http://www.postgresql.org/docs/current/static/plpgsql-errors-and-messages.html

Note that the client must have set the value of "client_min_messages" to the appropriate level in order to receive the "notice".

pgAdmin has a debugger for functions: http://www.pgadmin.org/docs/1.18/debugger.html

(But I have never use it as I don't use pgAdmin).

Solution 2

It sounds like you're looking for actual debugging capability. PostgreSQL actually introduced this functionality starting with PostgreSQL 8.3.

It's fantastic and totally makes PostgreSQL live up to it's tagline "the world's most advanced open source database". It's kind of a hassle to get running but these links might help get you started. Once enabled it allows you to set breakpoints or define inputs & evaluate functions all through a handy right-click menu in PGAdmin.

Solution 3

Along with the trusty ol' RAISE commands, there are also a couple 3rd-party tools that I have heard of, though I've never used them.

• PLPGSQL Lint: https://github.com/okbob/plpgsql_lint
• EDB Debugger: http://www.enterprisedb.com/docs/en/9.0/asguide/Postgres_Plus_Advanced_Server_Guide-17.htm. My understanding is that the EnterpriseDB Debugger comes bundled with their Postgres Studio package.

Solution 4

There is a debugger for PGAdmin: I tried this in ubuntu environment with Postgres 12 and it worked for me:

1. install this package

   apt-get install postgresql-12-pldebugger

2. Run this command in the database where resides your Procedure

   CREATE EXTENSION pldbgapi;

3. In your Postgresql installation folder and precisely in the data folder change this parameter in the postgresql.conf file

   shared_preload_libraries = 'plugin_debugger'

NB: you need to restart your Postgres after making this change

4. in pgAdmin right click on the procedure present in the list of the procedures in your schema, put the values for parameters and choose debug

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Comments

[Nawar]

Postgres Plus Advanced Server seems like a really cool thing, but it is off scope for me, since it requires a license to be purchased and that license is quite pricey for an individual.

[Diogo Alves]

Do you know if is possible to evaluate or figure out a var value that was not declared? Like from a select into...