Horton

Re: postgres_fdw bug in 9.6

Robert Haas <robertmhaas@gmail.com>

View thread View on postgr.es
From: Robert Haas <robertmhaas@gmail.com>
To: Etsuro Fujita <fujita.etsuro@lab.ntt.co.jp>
Cc: Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>, Jeff Janes <jeff.janes@gmail.com>, Tom Lane <tgl@sss.pgh.pa.us>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-01-12T15:43:02Z
Lists: pgsql-hackers 
On Wed, Jan 11, 2017 at 2:45 AM, Etsuro Fujita
<fujita.etsuro@lab.ntt.co.jp> wrote:
> As I said before, that might be fine for 9.6, but I don't think it's a good
> idea to search the pathlist because once we support parameterized foreign
> join paths, which is on my TODOs, we would have to traverse through the
> possibly-lengthy pathlist to find a local-join path, as mentioned in [3].

I'm not sure that's really going to be a problem.  The number of
possible parameterizations that need to be considered isn't usually
very big.  I bet the path list will have ten or a few tens of entries
in it, not a hundred or a thousand.  Traversing it isn't that
expensive.

That having been said, I haven't read the patches, so I'm not really
up to speed on the bigger issues here.  But surely it's more important
to get the overall design right than to worry about the cost of
walking the pathlist or worrying about the cost of an extra function
call (?!).

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Fix test case for 'outer pathkeys do not match mergeclauses' fix.

  2. postgres_fdw: Avoid 'outer pathkeys do not match mergeclauses' error.

  3. postgres_fdw: Consider foreign joining and foreign sorting together.

  4. Allow foreign and custom joins to handle EvalPlanQual rechecks.

  5. Allow FDWs to push down quals without breaking EvalPlanQual rechecks.