Message-ID: <929bd70f-cfc9-6b8e-e827-53555b6d77fe@enterprisedb.com>
Date: Sat, 15 Jan 2022 20:05:27 +0100
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Subject: Re: extended stats on partitioned tables
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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Zhihong Yu <zyu@yugabyte.com>,
 Jaime Casanova <jcasanov@systemguards.com.ec>, pgsql-hackers@postgresql.org
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On 1/15/22 19:35, Tomas Vondra wrote:
> On 1/15/22 06:11, Justin Pryzby wrote:
>> On Mon, Dec 13, 2021 at 09:40:09PM +0100, Tomas Vondra wrote:
>>> 1) If the table is a separate relation (not part of an inheritance
>>> tree), this should make no difference. -> OK
>>>
>>> 2) If the table is using "old" inheritance, this reverts back to
>>> pre-regression behavior. So people will keep using the old statistics
>>> until the ANALYZE, and we need to tell them to ANALYZE or something.
>>>
>>> 3) If the table is using partitioning, it's guaranteed to be empty and
>>> there are no stats at all. Again, we should tell people to run ANALYZE.
>>
>> I think these can be mentioned in the commit message, which can end up 
>> in the
>> minor release notes as a recommendation to rerun ANALYZE.
>>
> 
> Good point. I pushed the 0002 part and added a short paragraph 
> suggesting ANALYZE might be necessary. I did not go into details about 
> the individual cases, because that'd be too much for a commit message.
> 
>> Thanks for pushing 0001.
>>
> 
> Thanks for posting the patches!
> 
> I've pushed the second part - attached are the two remaining parts. I'll 
> wait a bit before pushing the rebased 0001 (which goes into master 
> branch only). Not sure about 0002 - I'm not convinced the refactored ACL 
> checks are an improvement, but I'll think about it.
> 

BTW when backpatching the first part, I had to decide what to do about 
tests. The 10 & 11 branches did not have the check_estimated_rows() 
function. I considered removing the tests, reworking the tests not to 
need the function, or adding the function. Ultimately I added the 
function, which seemed like the best option.


regards

-- 
Tomas Vondra
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