Re: Add index scan progress to pg_stat_progress_vacuum

On Thu, Apr 14, 2022 at 10:32 AM Imseih (AWS), Sami <simseih@amazon.com> wrote:
>
> Taking the above feedback, I modified the patches
> and I believe this approach should be acceptable.
>
> For now, I also reduced the scope to only exposing
> Indexes_total and indexes_completed in
> pg_stat_progress_vacuum. I will create a new CF entry
> for the new view pg_stat_progress_vacuum_index.
>
> V10-0001: This patch adds a callback to ParallelContext
> that could be called by the leader in vacuumparallel.c
> and more importantly while the leader is waiting
> for the parallel workers to complete inside.

Thank you for updating the patch! The new design looks much better to me.

 typedef struct ParallelWorkerInfo
@@ -46,6 +49,8 @@ typedef struct ParallelContext
    ParallelWorkerInfo *worker;
    int         nknown_attached_workers;
    bool       *known_attached_workers;
+   ParallelProgressCallback parallel_progress_callback;
+   void            *parallel_progress_callback_arg;
 } ParallelContext;

I think we can pass the progress update function to
WaitForParallelWorkersToFinish(), which seems simpler. And we can call
the function after updating the index status to
PARALLEL_INDVAC_STATUS_COMPLETED.

BTW, currently we don't need a lock for touching index status since
each worker touches different indexes. But after this patch, the
leader will touch all index status, do we need a lock for that?

Regards,

--
Masahiko Sawada
EDB:  https://www.enterprisedb.com/