Re: Performance of ByteA: ascii vs binary

Am 19.03.19 um 20:37 schrieb Peter J. Holzer:
> On 2019-03-18 15:33:17 +0100, Thomas Güttler wrote:
>> I did some benchmarking and in my setup there was major
>> performance difference.
>>
>> I tested a ByteA column.
>>
>> If I used ascii data the tests took 52 seconds.
>> If I used random binary data the test took 250 seconds.
>>
>> binary data is (roughly) five times slower than ascii data?
>>
>> Is this a know fact, or is there something wrong with my benchmark?
>>
>> I used Python and psycopg2.
>
> I don't see this here (Debian 9, Python 3,5, psycopg2 2.7.6, PostgreSQL
> 9.5).
>
> I modified my bench-bytea script (https://github.com/hjp/blob-bench) to
> restrict the byte values to printable ASCII (32 .. 126). There was
> absolutely no difference, as the attached graph shows.

Strange. I saw a big difference.
What did you test?
I tested inserts.

Regards,
Thomas Güttler

--
Thomas Guettler http://www.thomas-guettler.de/
I am looking for feedback: https://github.com/guettli/programming-guidelines