Re: RFC: Logging plan of the running query

On 2021/08/10 21:22, torikoshia wrote:
> I have updated the patch in this way.

Thanks for updating the patch!


> In this patch, getting the plan to the DO statement is as follows.

Looks good to me.


> Any thoughts?

+    ereport(LOG_SERVER_ONLY,
+            (errmsg("plan of the query running on backend with PID %d is:\n%s",
+                    MyProcPid, es->str->data),
+             errhidestmt(true)));

Shouldn't we hide context information by calling errhidecontext(true)?



While "make installcheck" regression test was running, I repeated
executing pg_log_current_query_plan() and got the failure of join_hash test
with the following diff. This means that pg_log_current_query_plan() could
cause the query that should be completed successfully to fail with the error.
Isn't this a bug?

I *guess* that the cause of this issue is that ExplainNode() can call
InstrEndLoop() more than once unexpectedly.

  ------------------------------------------------------------------------------
  $$
    select count(*) from simple r join simple s using (id);
  $$);
- initially_multibatch | increased_batches
-----------------------+-------------------
- f                    | f
-(1 row)
-
+ERROR:  InstrEndLoop called on running node
+CONTEXT:  PL/pgSQL function hash_join_batches(text) line 6 at FOR over EXECUTE statement
  rollback to settings;
  -- parallel with parallel-oblivious hash join
  savepoint settings;
@@ -687,11 +684,9 @@
      left join (select b1.id, b1.t from join_bar b1 join join_bar b2 using (id)) ss
      on join_foo.id < ss.id + 1 and join_foo.id > ss.id - 1;
  $$);
- multibatch
-------------
- t
-(1 row)
-
+ERROR:  InstrEndLoop called on running node
+CONTEXT:  parallel worker
+PL/pgSQL function hash_join_batches(text) line 6 at FOR over EXECUTE statement
  rollback to settings;
  -- single-batch with rescan, parallel-aware
  savepoint settings;
  ------------------------------------------------------------------------------

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION