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* Re: explain
@ 2025-04-24 13:41 David Rowley <[email protected]>
2025-04-24 13:51 ` Re: explain Marc Millas <[email protected]>
2025-04-24 15:06 ` Re: explain Laurenz Albe <[email protected]>
0 siblings, 2 replies; 5+ messages in thread
From: David Rowley @ 2025-04-24 13:41 UTC (permalink / raw)
To: Marc Millas <[email protected]>; +Cc: [email protected] <[email protected]>
On Fri, 25 Apr 2025 at 01:32, Marc Millas <[email protected]> wrote:
> Nested Loop Left Join (cost=941400.77..966327.57 rows=3 width=653) (actual time=52655.694..62533.811 rows=346 loops=1)
> Buffers: shared hit=10068265 read=396705 dirtied=1858 written=218, temp read=429687 written=115187
> I/O Timings: read=79368.246 write=11.486
>
> So, the total execution time is 52655 ms ok
> and the total time for i/o is...79368 ms
>
> how ???
The 79.3 seconds is the total time spent doing reads for all parallel
workers. 52.6 seconds is the wall clock time elapsed to execute the
query.
David
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: explain
2025-04-24 13:41 Re: explain David Rowley <[email protected]>
@ 2025-04-24 13:51 ` Marc Millas <[email protected]>
1 sibling, 0 replies; 5+ messages in thread
From: Marc Millas @ 2025-04-24 13:51 UTC (permalink / raw)
To: David Rowley <[email protected]>; +Cc: [email protected] <[email protected]>
Thanks !
Marc MILLAS
Senior Architect
+33607850334
www.mokadb.com
On Thu, Apr 24, 2025 at 3:41 PM David Rowley <[email protected]> wrote:
> On Fri, 25 Apr 2025 at 01:32, Marc Millas <[email protected]> wrote:
> > Nested Loop Left Join (cost=941400.77..966327.57 rows=3 width=653)
> (actual time=52655.694..62533.811 rows=346 loops=1)
> > Buffers: shared hit=10068265 read=396705 dirtied=1858 written=218,
> temp read=429687 written=115187
> > I/O Timings: read=79368.246 write=11.486
> >
> > So, the total execution time is 52655 ms ok
> > and the total time for i/o is...79368 ms
> >
> > how ???
>
> The 79.3 seconds is the total time spent doing reads for all parallel
> workers. 52.6 seconds is the wall clock time elapsed to execute the
> query.
>
> David
>
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: explain
2025-04-24 13:41 Re: explain David Rowley <[email protected]>
@ 2025-04-24 15:06 ` Laurenz Albe <[email protected]>
2025-04-25 00:36 ` Re: explain David Rowley <[email protected]>
1 sibling, 1 reply; 5+ messages in thread
From: Laurenz Albe @ 2025-04-24 15:06 UTC (permalink / raw)
To: David Rowley <[email protected]>; Marc Millas <[email protected]>; +Cc: [email protected] <[email protected]>
On Fri, 2025-04-25 at 01:41 +1200, David Rowley wrote:
> On Fri, 25 Apr 2025 at 01:32, Marc Millas <[email protected]> wrote:
> > Nested Loop Left Join (cost=941400.77..966327.57 rows=3 width=653) (actual time=52655.694..62533.811 rows=346 loops=1)
> > Buffers: shared hit=10068265 read=396705 dirtied=1858 written=218, temp read=429687 written=115187
> > I/O Timings: read=79368.246 write=11.486
> >
> > So, the total execution time is 52655 ms ok
> > and the total time for i/o is...79368 ms
> >
> > how ???
>
> The 79.3 seconds is the total time spent doing reads for all parallel
> workers. 52.6 seconds is the wall clock time elapsed to execute the
> query.
But wouldn't it read "loops=3" or similar then?
Yours,
Laurenz Albe
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: explain
2025-04-24 13:41 Re: explain David Rowley <[email protected]>
2025-04-24 15:06 ` Re: explain Laurenz Albe <[email protected]>
@ 2025-04-25 00:36 ` David Rowley <[email protected]>
2025-04-25 06:02 ` Re: explain Laurenz Albe <[email protected]>
0 siblings, 1 reply; 5+ messages in thread
From: David Rowley @ 2025-04-25 00:36 UTC (permalink / raw)
To: Laurenz Albe <[email protected]>; +Cc: Marc Millas <[email protected]>; [email protected] <[email protected]>
On Fri, 25 Apr 2025 at 03:06, Laurenz Albe <[email protected]> wrote:
>
> On Fri, 2025-04-25 at 01:41 +1200, David Rowley wrote:
> > The 79.3 seconds is the total time spent doing reads for all parallel
> > workers. 52.6 seconds is the wall clock time elapsed to execute the
> > query.
>
> But wouldn't it read "loops=3" or similar then?
Only if the Nested Loop was below the Gather / Gather Merge node.
David
^ permalink raw reply [nested|flat] 5+ messages in thread
* Re: explain
2025-04-24 13:41 Re: explain David Rowley <[email protected]>
2025-04-24 15:06 ` Re: explain Laurenz Albe <[email protected]>
2025-04-25 00:36 ` Re: explain David Rowley <[email protected]>
@ 2025-04-25 06:02 ` Laurenz Albe <[email protected]>
0 siblings, 0 replies; 5+ messages in thread
From: Laurenz Albe @ 2025-04-25 06:02 UTC (permalink / raw)
To: David Rowley <[email protected]>; +Cc: Marc Millas <[email protected]>; [email protected] <[email protected]>
On Fri, 2025-04-25 at 12:36 +1200, David Rowley wrote:
> On Fri, 25 Apr 2025 at 03:06, Laurenz Albe <[email protected]> wrote:
> > On Fri, 2025-04-25 at 01:41 +1200, David Rowley wrote:
> > > The 79.3 seconds is the total time spent doing reads for all parallel
> > > workers. 52.6 seconds is the wall clock time elapsed to execute the
> > > query.
> >
> > But wouldn't it read "loops=3" or similar then?
>
> Only if the Nested Loop was below the Gather / Gather Merge node.
Ah, I see. The I/O time accrued in a different, lower, parallelized step
of the execution plan.
Yours,
Laurenz Albe
^ permalink raw reply [nested|flat] 5+ messages in thread
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2025-04-24 13:41 Re: explain David Rowley <[email protected]>
2025-04-24 13:51 ` Marc Millas <[email protected]>
2025-04-24 15:06 ` Laurenz Albe <[email protected]>
2025-04-25 00:36 ` David Rowley <[email protected]>
2025-04-25 06:02 ` Laurenz Albe <[email protected]>
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