Subject: Re: PoC/WIP: Extended statistics on expressions
To: Noah Misch <noah@leadboat.com>
Cc: Dean Rasheed <dean.a.rasheed@gmail.com>,
 Justin Pryzby <pryzby@telsasoft.com>,
 PostgreSQL Hackers <pgsql-hackers@postgresql.org>
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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
Message-ID: <b6d73725-a324-47c2-cabd-777f20193751@enterprisedb.com>
Date: Fri, 11 Jun 2021 13:04:36 +0200
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On 6/11/21 6:55 AM, Noah Misch wrote:
> On Sun, Jun 06, 2021 at 09:13:17PM +0200, Tomas Vondra wrote:
>>
>> On 6/6/21 7:37 AM, Noah Misch wrote:
>>> On Sat, Mar 27, 2021 at 01:17:14AM +0100, Tomas Vondra wrote:
>>>> OK, pushed after a bit more polishing and testing.
>>>
>>> This added a "transformed" field to CreateStatsStmt, but it didn't mention
>>> that field in src/backend/nodes.  Should those functions handle the field?
>>>
>>
>> Yup, that's a mistake - it should do whatever CREATE INDEX is doing. Not
>> sure if it can result in error/failure or just inefficiency (due to
>> transforming the expressions repeatedly), but it should do whatever
>> CREATE INDEX is doing.
>>
>> Thanks for noticing! Fixed by d57ecebd12.
> 
> Great.  For future reference, this didn't need a catversion bump.  readfuncs.c
> changes need a catversion bump, since the catalogs might contain input for
> each read function.  Other src/backend/nodes functions don't face that.  Also,
> src/backend/nodes generally process fields in the order that they appear in
> the struct.  The order you used in d57ecebd12 is nicer, being more like
> IndexStmt, so I'm pushing an order change to the struct.
> 

OK, makes sense. Thanks!

-- 
Tomas Vondra
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