Robert Haas <robertmhaas@gmail.com> writes: > On Thu, Feb 26, 2015 at 1:53 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote: >> To some extent this is a workaround for the fact that plpgsql does type >> conversions the way it does (ie, by I/O rather than by using the parser's >> cast mechanisms). We've talked about changing that, but people seem to >> be afraid of the compatibility consequences, and I'm not planning to fight >> two compatibility battles concurrently ;-)
> A sensible plan, but since we're here:
> - I do agree that changing the way PL/pgsql does those type > conversions is scary. I can't predict what will break, and there's no > getting around the scariness of that.
> - On the other hand, I do think it would be good to change it, because > this sucks:
> rhaas=# do $$ declare x int; begin x := (3.0::numeric)/(1.0::numeric); end $$; > ERROR: invalid input syntax for integer: "3.0000000000000000" > CONTEXT: PL/pgSQL function inline_code_block line 1 at assignment
If we did want to open that can of worms, my proposal would be to make plpgsql type conversions work like so:
* If there is a cast pathway known to the core SQL parser, use that mechanism.
* Otherwise, attempt to convert via I/O as we do today.
This seems to minimize the risk of breaking things, although there would probably be corner cases that work differently (for instance I bet boolean to text might turn out differently). In the very long run we could perhaps deprecate and remove the second phase.
+1
There can be similar solution like plpgsql/sql identifiers priority configuration. Some levels - and what you are proposing should be default.
It works perfectly - and from my view and what I know from my neighborhood, there are no issues.
