Re: Using LIMIT 1 in plpgsql PERFORM statements

Karl,

> I like to write PERFORMs that return a constant when
> selecting from a table. It emphasizes that the
> selection is being done for its side effects.

Well, there's always the destruction test: run each version of the function
10,000 times and see if there's an execution time difference.

> (Programs should be written for people to read
> and only incidentally for computers to execute.
> Programs that people can't read quickly
> become useless whereas programs that can't run
> quickly can be fixed. Computers are easy.
> People are difficult.)

That's a nice sentiment, but I don't see how it applies. For example, if I
do:

SELECT id INTO v_check
FROM some_table ORDER BY id LIMIT 1;

IF id > 0 THEN ....

... that says pretty clearly to code maintainers that I'm only interested in
finding out whether there's any rows in the table, while making sure I use
the index on ID. If I want to make it more clear, I do:

-- check whether the table is populated

Not that there's anything wrong with your IF FOUND approach, but let's not mix
up optimizations and making your code pretty ... especially for a SQL
scripting language.

--
Josh Berkus
Aglio Database Solutions
San Francisco