Re: WIP: Upper planner pathification

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От Amit Kapila
Тема Re: WIP: Upper planner pathification
Дата
Msg-id CAA4eK1++4wVcTj-+qPsJm4JSfr0Emz6N8diGxtaW6nX-dDcUCA@mail.gmail.com
обсуждение исходный текст
Ответ на Re: WIP: Upper planner pathification  (Tom Lane <tgl@sss.pgh.pa.us>)
Ответы Re: WIP: Upper planner pathification  (Amit Kapila <amit.kapila16@gmail.com>)
Re: WIP: Upper planner pathification  (Tom Lane <tgl@sss.pgh.pa.us>)
Список pgsql-hackers
Дерево обсуждения
On Fri, Mar 4, 2016 at 11:31 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>
> OK, here is a version that I think addresses all of the recent comments:
>
> * Fixed handling of parallel-query fields in new path node types.
> (BTW, I found what seemed to be a couple of pre-existing bugs of
> the same kind, eg create_mergejoin_path was different from the
> other two kinds of join as to setting parallel_degree.)
>

I think the reason for keeping parallel_degree as zero for mergejoin path is that currently it can't participate in parallelism.


*************** create_unique_path(PlannerInfo *root, Re
*** 1440,1446 ****
  pathnode->path.param_info = subpath-
>param_info;
  pathnode->path.parallel_aware = false;
  pathnode->path.parallel_safe = subpath->parallel_safe;
! 
pathnode->path.parallel_degree = 0;
  
  /*
  * Assume the output is unsorted, since we don't necessarily 
have pathkeys
--- 1445,1451 ----
  pathnode->path.param_info = subpath->param_info;
  pathnode-
>path.parallel_aware = false;
  pathnode->path.parallel_safe = subpath->parallel_safe;
! pathnode-
>path.parallel_degree = subpath->parallel_degree;

Similar to reason for merge join path, I think this should also be set to 0.

Similarly for LimitPath, parallel_degree should be set to 0.


+ RecursiveUnionPath *
+ create_recursiveunion_path(PlannerInfo *root,
+   RelOptInfo *rel,
+   Path *leftpath,
+   Path *rightpath,
+   PathTarget *target,
+   List *distinctList,
+   int wtParam,
+   double numGroups)
+ {
+ RecursiveUnionPath *pathnode = makeNode(RecursiveUnionPath);
+ 
+ pathnode->path.pathtype = T_RecursiveUnion;
+ pathnode->path.parent = rel;
+ pathnode->path.pathtarget = target;
+ /* For now, assume we are above any joins, so no parameterization */
+ pathnode->path.param_info = NULL;
+ pathnode->path.parallel_aware = false;
+ pathnode->path.parallel_safe =
+ leftpath->parallel_safe && rightpath->parallel_safe;

I think here we should use rel->consider_parallel to set parallel_safe as is done in create_mergejoin_path.

+  * It's only needed atop a node that doesn't support projection

"needed atop a node", seems unclear to me, typo?


With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

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