Shigeru HANADA <hanada@metrosystems.co.jp> writes:
> Thanks, now I see your point. Current FdwRoutine has no appropriate
> function because Open is called from ExecutorStart which is used by
> EXPLAIN too.
> But then we have mismatch between executor node interface and FDW
> interface about BeginScan. Should we add new function such as
> ExecBeginNode and call ExecBeginXXX for each plan node?
That seems like a massive amount of new code, and wasted cycles during
every query startup, to fix a very small problem.
There's a flag EXEC_FLAG_EXPLAIN_ONLY that tells node Init functions
whether the query is going to be run "for real" or only EXPLAINed.
Use that to decide whether to do any real work.
regards, tom lane