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Date: Fri, 16 Aug 2024 17:32:17 +0200
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Subject: Re: Parallel CREATE INDEX for BRIN indexes
To: Tomas Vondra <tomas@vondra.me>
Cc: Andres Freund <andres@anarazel.de>,
 Matthias van de Meent <boekewurm+postgres@gmail.com>,
 PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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From: Peter Eisentraut <peter@eisentraut.org>
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On 16.08.24 11:22, Tomas Vondra wrote:
>> These pageinspect tests added a new use of the md5() function.  We got
>> rid of those in the tests for PG17.  You could write the test case with
>> something like
>>
>>   SELECT (CASE WHEN (mod(i,231) = 0) OR (i BETWEEN 3500 AND 4000) THEN
>> NULL ELSE i END),
>> -       (CASE WHEN (mod(i,233) = 0) OR (i BETWEEN 3750 AND 4250) THEN
>> NULL ELSE md5(i::text) END),
>> +       (CASE WHEN (mod(i,233) = 0) OR (i BETWEEN 3750 AND 4250) THEN
>> NULL ELSE encode(sha256(i::text::bytea), 'hex') END),
>>          (CASE WHEN (mod(i,233) = 0) OR (i BETWEEN 3850 AND 4500) THEN
>> NULL ELSE (i/100) + mod(i,8) END)
>>
>> But this changes the test output slightly and I'm not sure if this gives
>> you the data distribution that you need for you test.  Could your check
>> this please?
>>
> 
> I think this is fine. The output only changes because sha256 produces
> longer values than md5, so that the summaries are longer the index gets
> a page longer. AFAIK that has no impact on the test.

Ok, I have committed that.  Thanks for checking.