Re: Relation extension scalability - Mailing list pgsql-hackers
| From | Dilip Kumar |
|---|---|
| Subject | Re: Relation extension scalability |
| Date | |
| Msg-id | CAFiTN-uY7kF0RC8MR07sbmUbZQ91bHLmjiUc64AOM4G=VJCeLg@mail.gmail.com Whole thread Raw |
| In response to | Re: Relation extension scalability (Andres Freund <andres@anarazel.de>) |
| Responses |
Re: Relation extension scalability
(Amit Kapila <amit.kapila16@gmail.com>)
|
| List | pgsql-hackers |
On Thu, Jan 7, 2016 at 4:53 PM, Andres Freund <andres@anarazel.de> wrote:
On 2016-01-07 16:48:53 +0530, Amit Kapila wrote:
I think it's a worthwhile approach to pursue. But until it actually
fixes the problem of leaving around uninitialized pages I don't think
it's very meaningful to do performance comparisons.
Attached patch solves this issue, I am allocating the buffer for each page and initializing the page, only after that adding to FSM.
> a. Extend the relation page by page and add it to FSM without initializing
> it. I think this is what the current patch of Dilip seems to be doing. If
> we
I think that's pretty much unacceptable, for the non-error path at
least.
Performance results:
----------------------------
Test Case:
------------
./psql -d postgres -c "COPY (select g.i::text FROM generate_series(1, 10000) g(i)) TO '/tmp/copybinary' WITH BINARY";
echo COPY data from '/tmp/copybinary' WITH BINARY; > copy_script
./psql -d postgres -c "truncate table data"
./psql -d postgres -c "checkpoint"
./pgbench -f copy_script -T 120 -c$ -j$ postgres
Test Summary:
--------------------
1. I have measured the performance of base and patch.
2. With patch there are multiple results, that are with different values of "extend_num_pages" (parameter which says how many extra block to extend)
Test with Data on magnetic Disk and WAL on SSD
--------------------------------------------------------------------
Shared Buffer : 48GB
max_wal_size : 10GB
Storage : Magnetic Disk
WAL : SSD
tps with different value of extend_num_page
------------------------------------------------------------
Client Base 10-Page 20-Page 50-Page
1 105 103 157 129
2 217 219 255 288
4 210 421 494 486
8 166 605 702 701
16 145 484 563 686
32 124 477 480 745
Test with Data and WAL on SSD
-----------------------------------------------
Shared Buffer : 48GB
Max Wal Size : 10GB
Storage : SSD
tps with different value of extend_num_page
------------------------------------------------------------
Client Base 10-Page 20-Page 50-Page 100-Page
1 152 153 155 147 157
2 281 281 292 275 287
4 236 505 502 508 514
8 171 662 687 767 764
16 145 527 639 826 907
Note: Test with both data and WAL on Magnetic Disk : No significant improvement visible
-- I think wall write is becoming bottleneck in this case.
----------------------------
Test Case:
------------
./psql -d postgres -c "COPY (select g.i::text FROM generate_series(1, 10000) g(i)) TO '/tmp/copybinary' WITH BINARY";
echo COPY data from '/tmp/copybinary' WITH BINARY; > copy_script
./psql -d postgres -c "truncate table data"
./psql -d postgres -c "checkpoint"
./pgbench -f copy_script -T 120 -c$ -j$ postgres
Test Summary:
--------------------
1. I have measured the performance of base and patch.
2. With patch there are multiple results, that are with different values of "extend_num_pages" (parameter which says how many extra block to extend)
Test with Data on magnetic Disk and WAL on SSD
--------------------------------------------------------------------
Shared Buffer : 48GB
max_wal_size : 10GB
Storage : Magnetic Disk
WAL : SSD
tps with different value of extend_num_page
------------------------------------------------------------
Client Base 10-Page 20-Page 50-Page
1 105 103 157 129
2 217 219 255 288
4 210 421 494 486
8 166 605 702 701
16 145 484 563 686
32 124 477 480 745
Test with Data and WAL on SSD
-----------------------------------------------
Shared Buffer : 48GB
Max Wal Size : 10GB
Storage : SSD
tps with different value of extend_num_page
------------------------------------------------------------
Client Base 10-Page 20-Page 50-Page 100-Page
1 152 153 155 147 157
2 281 281 292 275 287
4 236 505 502 508 514
8 171 662 687 767 764
16 145 527 639 826 907
Note: Test with both data and WAL on Magnetic Disk : No significant improvement visible
-- I think wall write is becoming bottleneck in this case.
Currently i have kept extend_num_page as session level parameter but i think later we can make this as table property.
Any suggestion on this ?
Apart from this approach, I also tried extending the file in multiple block in one extend call, but this approach (extending one by one) is performing better.
Any suggestion on this ?
Apart from this approach, I also tried extending the file in multiple block in one extend call, but this approach (extending one by one) is performing better.
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