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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
To: Justin Pryzby <pryzby@telsasoft.com>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>
Cc: hackers <pgsql-hackers@postgresql.org>
Subject: Re: PoC/WIP: Extended statistics on expressions
Date: Wed, 1 Sep 2021 21:56:20 +0200
Message-ID: <7d3c842e-778e-d780-94da-f216c1002d14@enterprisedb.com> (raw)
In-Reply-To: <20210901193816.GO26465@telsasoft.com>
References: <20201123022604.GD24052@telsasoft.com>
	<e5beb5d5-28b4-7aad-3a16-9a6abf57f897@enterprisedb.com>
	<6455e0ad-2a2e-bdb0-e1f8-fd4983d1c8aa@enterprisedb.com>
	<087086de-1384-8374-4efc-2e7915071d5c@enterprisedb.com>
	<CAEZATCU9uPo7JYdx4k0-ufXXZH8t7itodibUwCva+s+AvAKcnw@mail.gmail.com>
	<b2995773-c9a1-5d3b-fc90-4f3ab189be11@enterprisedb.com>
	<20210816013255.GS10479@telsasoft.com>
	<a2be7e05-e6b7-1467-d15a-49011e45a4b8@enterprisedb.com>
	<20210824131320.GO10479@telsasoft.com>
	<6bc0ab0c-a807-2b7f-7df8-ac90c7839013@enterprisedb.com>
	<20210901193816.GO26465@telsasoft.com>



On 9/1/21 9:38 PM, Justin Pryzby wrote:
> On Wed, Sep 01, 2021 at 06:45:29PM +0200, Tomas Vondra wrote:
>>>> Patch 0001 fixes the "double parens" issue discussed elsewhere in this
>>>> thread, and patch 0002 tweaks CREATE STATISTICS to treat "(a)" as a simple
>>>> column reference.
>>>
>>> 0002 refuses to create expressional stats on a simple column reference like
>>> (a), which I think is helps to avoid a user accidentally creating useless ext
>>> stats objects (which are redundant with the table's column stats).
>>>
>>> 0002 does not attempt to refuse cases like (a+0), which I think is fine:
>>> we don't try to reject useless cases if someone insists on it.
>>> See 240971675, 701fd0bbc.
>>>
>>> So I am +1 to apply both patches.
>>>
>>> I added this as an Opened Item for increased visibility.
>>
>> I've pushed both fixes, so the open item should be resolved.
> 
> Thank you - I marked it as such.
> 
> There are some typos in 537ca68db (refenrece)
> I'll add them to my typos branch if you don't want to patch them right now or
> wait to see if someone notices anything else.
> 

Yeah, probably better to wait a bit. Any opinions on rejecting 
expressions referencing system attributes or no attributes at all?

regards

-- 
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company





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