Re: Sequence vs UUID

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(at)gmail(dot)com> wrote:

> On Fri, Feb 3, 2023 at 5:48 PM veem v <veema0000(at)gmail(dot)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. --DD
>
> sqlite> 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 0.000000
>
>
>> On Fri, 3 Feb 2023 at 21:28, Dominique Devienne <ddevienne(at)gmail(dot)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:
>>>
>>