Re: Re: regexp_matches illegally restricts rows -- just a documentation issue?

On Tue, April 6, 2010 21:42, Josh Berkus wrote:
>
>> While I understand why this is confusing, it's really very normal
>> behavior for a SRF, and I don't really think it makes sense to
>> document that this SRF behaves just like other SRFs...
>
> It's likely to be used by people who do not otherwise use SRFs, and many
> would not be prepared for the consequences. It's not instinctive that a
> regexp function would be an SRF in any case; if someone is not looking
> closely at the docs, it would be easy to miss this entirely -- as 3
> experienced PG people did yesterday.
>
> Personally, I also think that PostgreSQL is wrong to allow an SRF in the
> target list to restrict the number of rows output. A subselect in the
> target list does not do so. However, that's completely another discussion.
>

You said:
"users should be warned in the documentation.";

The documentation has this warning:

"Currently, functions returning sets can also be called in the select list
of a query. For each row that the query generates by itself, the function
returning set is invoked, and an output row is generated for each element
of the function’s result set. Note, however, that this capability is
deprecated and might be removed in future releases."

(8.4 docs, section 34.4.7.)

Erik Rijkers