Re: Sequence vs UUID - Mailing list pgsql-general
| From | veem v |
|---|---|
| Subject | Re: Sequence vs UUID |
| Date | |
| Msg-id | CAB+=1TVcrK+jdUpdGYRcZ0OTOHgH6kkRrjzPupYp-VPTaVLfiw@mail.gmail.com Whole thread Raw |
| In response to | Re: Sequence vs UUID (Dominique Devienne <ddevienne@gmail.com>) |
| Responses |
Re: Sequence vs UUID
(Julian Backes <julianbackes@gmail.com>)
|
| List | pgsql-general |
So, it may be the machine on which the code is getting executed behind the scene , in the site "https://dbfiddle.uk/" is playing a key role in the speed, however, the comparative performance of UUID vs sequence should stay the same.
So I think, after this test we can safely conclude that if we compare the performance of the UUID(both version-4, version 7) VS sequence. The UUID performs a lot worse as compared to sequence. So unless there exists some strong reason/justification for UUID, we should default use the sequence. Correct me if I'm wrong. And also I understand the cases of multi master replication/sharding etc, may be a factor but other than that I can't think of any scenario where sequences can be used.
On Fri, 3 Feb 2023 at 23:07, Dominique Devienne <ddevienne@gmail.com> wrote:
On Fri, Feb 3, 2023 at 5:48 PM veem v <veema0000@gmail.com> wrote:Actually I did the testing by connecting to "https://dbfiddle.uk/" postgres version -15.
PostgreSQL 15.0 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 8.5.0 20210514 (Red Hat 8.5.0-10), 64-bit Am I doing it wrong, please confirm?No clue. But even SQLite can generate 1M uuid (16 bytes random blobs are equivalent) is 1/3 of the time, so 30x faster.So your timings of generating 100K uuids and counting them seems way too slow to me. --DDsqlite> select count(randomblob(16)) from generate_series(1,1000*1000);
QUERY PLAN
`--SCAN generate_series VIRTUAL TABLE INDEX 3:
addr opcode p1 p2 p3 p4 p5 comment
---- ------------- ---- ---- ---- ------------- -- -------------
0 Init 0 15 0 0 Start at 15
1 Null 0 1 1 0 r[1..1]=NULL
2 VOpen 0 0 0 vtab:274D3E0 0
3 Integer 1 4 0 0 r[4]=1
4 Multiply 6 6 5 0 r[5]=r[6]*r[6]
5 Integer 3 2 0 0 r[2]=3
6 Integer 2 3 0 0 r[3]=2
7 VFilter 0 11 2 0 iplan=r[2] zplan=''
8 Function 1 8 7 randomblob(1) 0 r[7]=func(r[8])
9 AggStep 0 7 1 count(1) 1 accum=r[1] step(r[7])
10 VNext 0 8 0 0
11 AggFinal 1 1 0 count(1) 0 accum=r[1] N=1
12 Copy 1 9 0 0 r[9]=r[1]
13 ResultRow 9 1 0 0 output=r[9]
14 Halt 0 0 0 0
15 Transaction 0 0 1 0 1 usesStmtJournal=0
16 Integer 1000 6 0 0 r[6]=1000
17 Integer 16 8 0 0 r[8]=16
18 Goto 0 1 0 0
┌───────────────────────┐
│ count(randomblob(16)) │
├───────────────────────┤
│ 1000000 │
└───────────────────────┘Run Time: real 0.278 user 0.250000 sys 0.000000On Fri, 3 Feb 2023 at 21:28, Dominique Devienne <ddevienne@gmail.com> wrote:Something's off regarding Guid generations IMHO...You generate 100K Guids in ~1s. While we generate (in C++, Windows Release, using Boost) 16M of them in +/- the same time:
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