Re: Parallel Full Hash Join
От | Melanie Plageman |
---|---|
Тема | Re: Parallel Full Hash Join |
Дата | |
Msg-id | 20210211220218.GA384835@goldwasser обсуждение исходный текст |
Ответ на | Re: Parallel Full Hash Join (Thomas Munro <thomas.munro@gmail.com>) |
Список | pgsql-hackers |
On Tue, Dec 29, 2020 at 03:28:12PM +1300, Thomas Munro wrote: > I had some feedback I meant to > post in November but didn't get around to: > > * PHJ_BATCH_PROBING -- all probe > - * PHJ_BATCH_DONE -- end > + > + * PHJ_BATCH_DONE -- queries not requiring inner fill done > + * PHJ_BATCH_FILL_INNER_DONE -- inner fill completed, all queries done > > Would it be better/tidier to keep _DONE as the final phase? That is, > to switch around these two final phases. Or does that make it too > hard to coordinate the detach-and-cleanup logic? I updated this to use your suggestion. My rationale for having PHJ_BATCH_DONE and then PHJ_BATCH_FILL_INNER_DONE was that, for a worker attaching to the batch for the first time, it might be confusing that it is in the PHJ_BATCH_FILL_INNER state (not the DONE state) and yet that worker still just detaches and moves on. It didn't seem intuitive. Anyway, I think that is all sort of confusing and unnecessary. I changed it to PHJ_BATCH_FILLING_INNER -- then when a worker who hasn't ever been attached to this batch before attaches, it will be in the PHJ_BATCH_FILLING_INNER phase, which it cannot help with and it will detach and move on. > > +/* > + * ExecPrepHashTableForUnmatched > + * set up for a series of ExecScanHashTableForUnmatched calls > + * return true if this worker is elected to do the > unmatched inner scan > + */ > +bool > +ExecParallelPrepHashTableForUnmatched(HashJoinState *hjstate) > > Comment name doesn't match function name. Updated -- and a few other comment updates too. I just attached the diff.
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