Horton

Re: executor relation handling

David Rowley <david.rowley@2ndquadrant.com>

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From: David Rowley <david.rowley@2ndquadrant.com>
To: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
Cc: Tom Lane <tgl@sss.pgh.pa.us>, Alvaro Herrera <alvherre@2ndquadrant.com>, Jesper Pedersen <jesper.pedersen@redhat.com>, Amit Langote <amitlangote09@gmail.com>, Pg Hackers <pgsql-hackers@postgresql.org>
Date: 2018-10-01T19:04:22Z
Lists: pgsql-hackers 
On 1 October 2018 at 19:39, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp> wrote:
> For this and the other cases (AcquireRewriteLocks, AcquireExecutorLocks,
> etc.), I wonder whether we couldn't just *not* recalculate the lock mode
> based on inspecting the query tree to cross-check with rellockmode?  Why
> not just use rellockmode for locking?  Maybe, okay to keep doing that in
> debug builds though.  Also, are the discrepancies like this to be
> considered bugs of the existing logic?

I got the impression Tom was just leaving that in for a while to let
the buildfarm verify the new code is getting the same lock level as
the old code. Of course, I might be wrong.

-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services

Commits

  1. Avoid O(N^2) cost in ExecFindRowMark().

  2. Remove some unnecessary fields from Plan trees.

  3. Restore sane locking behavior during parallel query.

  4. Remove more redundant relation locking during executor startup.

  5. In the executor, use an array of pointers to access the rangetable.

  6. Centralize executor's opening/closing of Relations for rangetable entries.

  7. Change executor to just Assert that table locks were already obtained.

  8. Change rewriter/planner/executor/plancache to depend on RTE rellockmode.

  9. Add assertions that we hold some relevant lock during relation open.

  10. Create an RTE field to record the query's lock mode for each relation.