Re: Sequence vs UUID

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:
>>
>