Debug SQL in pgAdmin when SQL contains variables

Question

In SQL Server I could copy sql code out of an application and paste it into SSMS, declare & assign vars that exist in the sql and run. yay great debugging scenario.

Answer 1

SQL procs are notoriously hard to debug. My lame but practical solution has been to write log messages to a log table, like this (please excuse syntax issues):

create table log_message (
  log_timestamp timestamp not null default current_timestamp,
  message varchar(1000)
);

then add lines to your stored proc like:

insert into log_message (message) values ("The value of x is " || @x);

Then after a run:

select * from log_message order by 1;

It's not pretty, but works in every DB.

Answer 2

You can achieve this using the PREPARE, EXECUTE, DEALLOCATE commands for handling statements, which is really what we are talking about here.

For example:

PREPARE test AS SELECT * FROM users WHERE first_name = $1;
EXECUTE test ('paul');
DEALLOCATE test;

Perhaps not as graphical as some may like, but certainly workable.

Answer 3

I would give a shot at writing a SQL function that wraps your query. It can be something as simple as

CREATE OR REPLACE FUNCTION my_function(integer, integer) 
RETURNS integer
AS
$$
    SELECT $1 + $2;
$$ 
LANGUAGE SQL;

SELECT my_function(1, 2);

I would do this instead of a PREPARE since it will be simpler to update it. Depending on how complex the function is, you might want to also look at some of the other PL's in Postgres.