Tom Lane wrote:
> Oh! What is happening is that to_number(1) is being reduced to constant
> NULL, whereupon it concludes that ad_tab_id=to_number(1) is constant
> NULL, ergo the EXISTS can never succeed, ergo the entire WHERE is
> constant false.
> CREATE FUNCTION to_number(integer) RETURNS numeric
> LANGUAGE plpgsql IMMUTABLE
> AS $_$
> BEGIN
> RETURN to_number($1, 'S99999999999999D999999');
> EXCEPTION
> WHEN OTHERS THEN
> RETURN NULL;
> END;
> $_$;
How can the executor "see through" a plpgsql function definition? Or do
you mean that this reduction is being done at execution time? (hmm ...
this is what a one-time filter is, now that I think about it?)
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
