Re: Why are default encoding conversions

Tatsuo Ishii <ishii@sraoss.co.jp> writes:
>> Well, being able to switch to a different conversion is fine, but I don't
>> think that's a good argument for tying it to the schema search path.

> If it does work, then it's ok. However still I'm not sure why current
> method is evil.

Because with the current definition, any change in search_path really
ought to lead to repeating the lookup for the default conversion proc.
That's a bad idea from a performance point of view and I don't think
it's a particularly good idea from the definitional point of view
either --- do you really want the client conversion changing because
some function altered the search path?

> BTW, what does the standard say about conversion vs. schema? Doesn't
> conversion belong to schema? If so, then schema specific default
> conversion seems more standard-friendly way.

AFAICT we invented the entire concept of conversions ourselves.  I see
nothing about CREATE CONVERSION in the SQL spec.  There is a CREATE
TRANSLATION in SQL2003, which we'd probably not seen when we invented
CREATE CONVERSION, but it does *not* have a DEFAULT clause.  I don't
think you can point to the spec to defend our current method of
selecting which conversion to use.
        regards, tom lane