Re: [HACKERS] Gather Merge - Mailing list pgsql-hackers

Hi, 

I have done some testing with the latest patch

1)./pgbench postgres -i -F 100 -s 20
2) update pgbench_accounts set filler = 'foo' where aid%10 = 0;
3) vacuum analyze pgbench_accounts;
4) set max_parallel_workers_per_gather = 4;

5) set max_parallel_workers = 4;

Machine Configuration :-

RAM    :- 16GB

VCPU  :- 8 

Disk     :- 640 GB

 

Test case script with out-file attached.

LCOV Report :- 

File Names	Line Coverage without Test cases	Line Coverage with Test cases	Function Coverage without Test cases	Function Coverage with Test cases
src/backend/executor/nodeGatherMerge.c	0.0 %	92.3 %	0.0 %	92.3 %
src/backend/commands/explain.c	65.5 %	68.4 %	81.7 %	85.0 %
src/backend/executor/execProcnode.c	92.50%	95.1 %	100%	100.0 %
src/backend/nodes/copyfuncs.c	77.2 %	77.6 %	73.0 %	73.4 %
src/backend/nodes/outfuncs.c	32.5 %	35.9 %	31.9 %	36.2 %
src/backend/nodes/readfuncs.c	62.7 %	68.2 %	53.3 %	61.7 %
src/backend/optimizer/path/allpaths.c	93.0 %	93.4 %	100 %	100%
src/backend/optimizer/path/costsize.c	96.7 %	96.8 %	100%	100%
src/backend/optimizer/plan/createplan.c	89.9 %	91.2 %	95.0 %	96.0 %
src/backend/optimizer/plan/planner.c	95.1 %	95.2 %	97.3 %	97.3 %
src/backend/optimizer/plan/setrefs.c	94.7 %	94.7 %	97.1 %	97.1 %
src/backend/optimizer/plan/subselect.c	94.1 %	94.1%	100%	100%
src/backend/optimizer/util/pathnode.c	95.6 %	96.1 %	100%	100%
src/backend/utils/misc/guc.c	67.4 %	67.4 %	91.9 %	91.9 %

On Wed, Feb 1, 2017 at 7:02 PM, Rushabh Lathia <rushabh.lathia@gmail.com> wrote:

Due to recent below commit, patch not getting apply cleanly on
master branch.

commit d002f16c6ec38f76d1ee97367ba6af3000d441d0
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date:   Mon Jan 30 17:15:42 2017 -0500

    Add a regression test script dedicated to exercising system views.

Please find attached latest patch.

On Wed, Feb 1, 2017 at 5:55 PM, Rushabh Lathia <rushabh.lathia@gmail.com> wrote:

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

--

Rushabh Lathia

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Regards,

Neha Sharma