Message-ID: <f0930823-d44b-21df-d718-ee3c657d9087@enterprisedb.com>
Date: Wed, 1 Nov 2023 21:07:27 +0100
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101
 Thunderbird/102.13.0
Subject: Re: Statistics Import and Export
To: Corey Huinker <corey.huinker@gmail.com>,
 Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Cc: pgsql-hackers@lists.postgresql.org
References: <CADkLM=cB0rF3p_FuWRTMSV0983ihTRpsH+OCpNyiqE7Wk0vUWA@mail.gmail.com>
 <CAExHW5uRNe856LPYH1eZFyeASv4Xs4-9d1Gqj+rzS+3StVGLxQ@mail.gmail.com>
 <CADkLM=c_iuAN19_94ikG5VeR_Z3LDkR6fKyeOz=ZKr44qweYjg@mail.gmail.com>
 <CADkLM=dTHVSrcGBAstjshoZBXKJgWjzN3Vj53KQ9fORqvkaN5Q@mail.gmail.com>
Content-Language: en-US
From: Tomas Vondra <tomas.vondra@enterprisedb.com>
In-Reply-To: <CADkLM=dTHVSrcGBAstjshoZBXKJgWjzN3Vj53KQ9fORqvkaN5Q@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Archived-At: <https://www.postgresql.org/message-id/f0930823-d44b-21df-d718-ee3c657d9087%40enterprisedb.com>
Precedence: bulk


On 10/31/23 08:25, Corey Huinker wrote:
>
> Attached is v2 of this patch.
> 
> New features:
> * imports index statistics. This is not strictly accurate: it 
> re-computes index statistics the same as ANALYZE does, which is to
> say it derives those stats entirely from table column stats, which
> are imported, so in that sense we're getting index stats without
> touching the heap.

Maybe I just don't understand, but I'm pretty sure ANALYZE does not
derive index stats from column stats. It actually builds them from the
row sample.

> * now support extended statistics except for MCV, which is currently 
> serialized as an difficult-to-decompose bytea field.

Doesn't pg_mcv_list_items() already do all the heavy work?


regards

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