Re: pgcon unconference / impact of block size on performance

2022-06-13 Thread Tomas Vondra
On 6/13/22 17:42, Merlin Moncure wrote: > On Sat, Jun 4, 2022 at 6:23 PM Tomas Vondra > mailto:tomas.von...@enterprisedb.com>> > wrote: > > Hi, > > At on of the pgcon unconference sessions a couple days ago, I presented > a bunch of benchmark results comparing performance with differe

Re: pgcon unconference / impact of block size on performance

2022-06-13 Thread Merlin Moncure
On Sat, Jun 4, 2022 at 6:23 PM Tomas Vondra wrote: > Hi, > > At on of the pgcon unconference sessions a couple days ago, I presented > a bunch of benchmark results comparing performance with different > data/WAL block size. Most of the OLTP results showed significant gains > (up to 50%) with smal

RE: pgcon unconference / impact of block size on performance

2022-06-10 Thread Jakub Wartak
> On 6/9/22 13:23, Jakub Wartak wrote: > >>> The really > >> puzzling thing is why is the filesystem so much slower for > >> smaller pages. I mean, why would writing 1K be 1/3 of writing 4K? > >> Why would a filesystem have such effect? > > > > Ha! I don't care at this point

Re: pgcon unconference / impact of block size on performance

2022-06-09 Thread Tomas Vondra
On 6/9/22 13:23, Jakub Wartak wrote: >>> The really >> puzzling thing is why is the filesystem so much slower for smaller >> pages. I mean, why would writing 1K be 1/3 of writing 4K? >> Why would a filesystem have such effect? > > Ha! I don't care at this point as 1 or 2

RE: pgcon unconference / impact of block size on performance

2022-06-09 Thread Jakub Wartak
> > The really > puzzling thing is why is the filesystem so much slower for smaller > pages. I mean, why would writing 1K be 1/3 of writing 4K? > Why would a filesystem have such effect? > >>> > >>> Ha! I don't care at this point as 1 or 2kB seems too small to handle > >>> many

Re: pgcon unconference / impact of block size on performance

2022-06-08 Thread Tomas Vondra
On 6/8/22 16:15, Jakub Wartak wrote: > Hi, got some answers! > > TL;DR for fio it would make sense to use many stressfiles (instead of 1) and > same for numjobs ~ VCPU to avoid various pitfails. > The really puzzling thing is why is the filesystem so much slower for smaller pages.

RE: pgcon unconference / impact of block size on performance

2022-06-08 Thread Jakub Wartak
Hi, got some answers! TL;DR for fio it would make sense to use many stressfiles (instead of 1) and same for numjobs ~ VCPU to avoid various pitfails. > >> The really > >> puzzling thing is why is the filesystem so much slower for smaller > >> pages. I mean, why would writing 1K be 1/3 of writing

Re: pgcon unconference / impact of block size on performance

2022-06-07 Thread Robert Haas
On Tue, Jun 7, 2022 at 1:47 PM Tomas Vondra wrote: > Possibly, but why would that be the case? Maybe there are places that do > stuff with memory and have different optimizations based on length? I'd > bet the 4k page is way more optimized than the other cases. I don't really know. It was just a

Re: pgcon unconference / impact of block size on performance

2022-06-07 Thread Tomas Vondra
On 6/7/22 18:26, Robert Haas wrote: > On Sat, Jun 4, 2022 at 7:23 PM Tomas Vondra > wrote: >> This opened a long discussion about possible explanations - I claimed >> one of the main factors is the adoption of flash storage, due to pretty >> fundamental differences between HDD and SSD systems. But

Re: pgcon unconference / impact of block size on performance

2022-06-07 Thread Robert Haas
On Sat, Jun 4, 2022 at 7:23 PM Tomas Vondra wrote: > This opened a long discussion about possible explanations - I claimed > one of the main factors is the adoption of flash storage, due to pretty > fundamental differences between HDD and SSD systems. But the discussion > concluded with an agreeme

Re: pgcon unconference / impact of block size on performance

2022-06-07 Thread Tomas Vondra
On 6/7/22 15:48, Jakub Wartak wrote: > Hi, > >> The really >> puzzling thing is why is the filesystem so much slower for smaller pages. I >> mean, >> why would writing 1K be 1/3 of writing 4K? >> Why would a filesystem have such effect? > > Ha! I don't care at this point as 1 or 2kB seems too

RE: pgcon unconference / impact of block size on performance

2022-06-07 Thread Jakub Wartak
Hi, > The really > puzzling thing is why is the filesystem so much slower for smaller pages. I > mean, > why would writing 1K be 1/3 of writing 4K? > Why would a filesystem have such effect? Ha! I don't care at this point as 1 or 2kB seems too small to handle many real world scenarios ;) > > b

Re: pgcon unconference / impact of block size on performance

2022-06-07 Thread Tomas Vondra
On 6/7/22 11:46, Jakub Wartak wrote: > Hi Tomas, > >> Well, there's plenty of charts in the github repositories, including the >> charts I >> think you're asking for: > > Thanks. > >> I also wonder how is this related to filesystem page size - in all the >> benchmarks I >> did I used the defau

RE: pgcon unconference / impact of block size on performance

2022-06-07 Thread Jakub Wartak
[..] >I doubt we could ever > make the default smaller than it is today as it would nobody would be able to > insert rows larger than 4 kilobytes into a table anymore. Add error "values larger than 1/3 of a buffer page cannot be indexed" to that list... -J.

RE: pgcon unconference / impact of block size on performance

2022-06-07 Thread Jakub Wartak
Hi Tomas, > Well, there's plenty of charts in the github repositories, including the > charts I > think you're asking for: Thanks. > I also wonder how is this related to filesystem page size - in all the > benchmarks I > did I used the default (4k), but maybe it'd behave if the filesystem page

Re: pgcon unconference / impact of block size on performance

2022-06-06 Thread David Rowley
On Sun, 5 Jun 2022 at 11:23, Tomas Vondra wrote: > At on of the pgcon unconference sessions a couple days ago, I presented > a bunch of benchmark results comparing performance with different > data/WAL block size. Most of the OLTP results showed significant gains > (up to 50%) with smaller (4k) da

Re: pgcon unconference / impact of block size on performance

2022-06-06 Thread Fabien COELHO
Hello Tomas, At on of the pgcon unconference sessions a couple days ago, I presented a bunch of benchmark results comparing performance with different data/WAL block size. Most of the OLTP results showed significant gains (up to 50%) with smaller (4k) data pages. You wrote something about SS

Re: pgcon unconference / impact of block size on performance

2022-06-06 Thread Tomas Vondra
On 6/6/22 17:00, Tomas Vondra wrote: > > On 6/6/22 16:27, Jakub Wartak wrote: >> Hi Tomas, >> >>> Hi, >>> >>> At on of the pgcon unconference sessions a couple days ago, I presented a >>> bunch of benchmark results comparing performance with different data/WAL >>> block size. Most of the OLTP r

Re: pgcon unconference / impact of block size on performance

2022-06-06 Thread Tomas Vondra
On 6/6/22 16:27, Jakub Wartak wrote: > Hi Tomas, > >> Hi, >> >> At on of the pgcon unconference sessions a couple days ago, I presented a >> bunch of benchmark results comparing performance with different data/WAL >> block size. Most of the OLTP results showed significant gains (up to 50%) >> w

RE: pgcon unconference / impact of block size on performance

2022-06-06 Thread Jakub Wartak
Hi Tomas, > Hi, > > At on of the pgcon unconference sessions a couple days ago, I presented a > bunch of benchmark results comparing performance with different data/WAL > block size. Most of the OLTP results showed significant gains (up to 50%) with > smaller (4k) data pages. Nice. I just saw th

Re: pgcon unconference / impact of block size on performance

2022-06-05 Thread Tomas Vondra
On 6/5/22 02:21, Roberto Mello wrote: > On Sat, Jun 4, 2022 at 5:23 PM Tomas Vondra > mailto:tomas.von...@enterprisedb.com>> > wrote: > > Hi, > > At on of the pgcon unconference sessions a couple days ago, I presented > a bunch of benchmark results comparing performance with differ

Re: pgcon unconference / impact of block size on performance

2022-06-04 Thread Roberto Mello
On Sat, Jun 4, 2022 at 5:23 PM Tomas Vondra wrote: > Hi, > > At on of the pgcon unconference sessions a couple days ago, I presented > a bunch of benchmark results comparing performance with different > data/WAL block size. Most of the OLTP results showed significant gains > (up to 50%) with smal