Re: Pathify RHS unique-ification for semijoin planning

Richard Guo <guofenglinux(at)gmail(dot)com> writes:
> Given this, I'd prefer to stick with "unique-ify", for consistency
> with the majority usage in the codebase.

+1. (Not but what I might've been responsible for many of the
existing usages, so my opinion is perhaps counting twice here.)

> In this patch, the only instance that doesn't follow the "unique-ify"
> form is the macro IS_UNIQUEIFIED_REL, as dashes are not allowed in C
> identifiers. Maybe a better alternative is IS_RELATION_UNIQUE? Any
> suggestions?

Hm ... to my ear, "unique-ified" implies that we took some positive
action to make the path's output unique, such as running it through
a hashagg or Unique node. IS_RELATION_UNIQUE only implies that the
output is unique, so for example a scan of a primary key should
satisfy such a predicate. Not having read the patch (I do hope
to get to that), I'm not sure which connotation you have in mind.
If it's the latter, IS_RELATION_UNIQUE seems like a fine name.
If it's the former, maybe something like "RELATION_WAS_MADE_UNIQUE"?
That's not very pretty though ...

regards, tom lane