Re: [HACKERS] Gather Merge

I am sorry for the delay, here is the latest re-based patch.

my colleague Neha Sharma, reported one regression with the patch, where

explain output for the Sort node under GatherMerge was always showing

cost as zero:

explain analyze select '' AS "xxx" from pgbench_accounts  where filler like '%foo%' order by aid;
                                                                   QUERY PLAN                                                                  
------------------------------------------------------------------------------------------------------------------------------------------------
 Gather Merge  (cost=47169.81..70839.91 rows=197688 width=36) (actual time=406.297..653.572 rows=200000 loops=1)
   Workers Planned: 4
   Workers Launched: 4
   ->  Sort  (cost=0.00..0.00 rows=0 width=0) (actual time=368.945..391.124 rows=40000 loops=5)
         Sort Key: aid
         Sort Method: quicksort  Memory: 3423kB
         ->  Parallel Seq Scan on pgbench_accounts  (cost=0.00..42316.60 rows=49422 width=36) (actual time=296.612..338.873 rows=40000 loops=5)
               Filter: (filler ~~ '%foo%'::text)
               Rows Removed by Filter: 360000
 Planning time: 0.184 ms
 Execution time: 734.963 ms

This patch also fix that issue.

On Wed, Feb 1, 2017 at 11:27 AM, Michael Paquier <michael.paquier@gmail.com> wrote:

On Mon, Jan 23, 2017 at 6:51 PM, Kuntal Ghosh
<kuntalghosh.2007@gmail.com> wrote:
> On Wed, Jan 18, 2017 at 11:31 AM, Rushabh Lathia
> <rushabh.lathia@gmail.com> wrote:
>>
> The patch needs a rebase after the commit 69f4b9c85f168ae006929eec4.

Is an update going to be provided? I have moved this patch to next CF
with "waiting on author" as status.
--
Michael

--

Rushabh Lathia