Test for null in function with varying parameters

Question

I have a Postgres function:

create function myfunction(integer, text, text, text, text, text, text) RETURNS 
table(id int, match text, score int, nr int, nr         


        

Answer 1

Several things...

First, as side note: the semantics of your query might need a revisit. Some of the stuff in your where clauses might actually belong in your join clauses, like:

from ...
left join ... on ... and ...
left join ... on ... and ...

When they don't, you most should probably be using an inner join, rather than a left join.

Second, there is a is not distinct from operator, which can occasionally be handy in place of =. a is not distinct from b is basically equivalent to a = b or a is null and b is null.

Note, however, that is not distinct from does NOT use an index, whereas = and is null actually do. You could use (field = $i or $i is null) instead in your particular case, and it will yield the optimal plan if you're using the latest version of Postgres:

https://gist.github.com/ddebernardy/5884267