Re: fdw_private and (List*) handling in FDW API - Mailing list pgsql-hackers

From Tom Lane
Subject Re: fdw_private and (List*) handling in FDW API
Date
Msg-id 8913.1382111556@sss.pgh.pa.us
Whole thread Raw
In response to fdw_private and (List*) handling in FDW API  ("Tomas Vondra" <tv@fuzzy.cz>)
Responses Re: fdw_private and (List*) handling in FDW API  ("Tomas Vondra" <tv@fuzzy.cz>)
List pgsql-hackers
"Tomas Vondra" <tv@fuzzy.cz> writes:
> 2) Is there any particular reason why PlanForeignModify/BeginForeignModify
> require the fdw_private to be a List*, and not a generic pointer?

That data has to be copiable by copyObject(), which a generic void* is
not.  We could perhaps have made it Node* instead, but that would only
work conveniently if there were infrastructure for plugins to create new
first-class Node types; which there isn't.  A List is often the easiest
way to transport a few random values from plan time to execution time,
so it seemed best to declare fdw_private that way.
        regards, tom lane



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