Re: [HACKERS] Parallel Index Scans

On Mon, Feb 13, 2017 at 9:04 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
> I think the comment at that place is not as clear as it should be.  So
> how about changing it as below:
>
> Existing comment:
> --------------------------
> /*
> * For parallel scans, get the last page scanned as it is quite
> * possible that by the time we try to fetch previous page, other
> * worker has also decided to scan that previous page.  So we
> * can't rely on _bt_walk_left call.
> */
>
> Modified comment:
> --------------------------
> /*
>  * For parallel scans, it is quite possible that by the time we try to fetch
>  * the previous page, another worker has also decided to scan that
>  * previous page.  So to avoid that we need to get the last page scanned
>  * from shared scan descriptor before calling _bt_walk_left.
>  */

That sounds way better.

-- 
Robert Haas
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