Re: Simple task with partitioning which I can't realize - Mailing list pgsql-performance

Hi Marc –

Since there is a DWH fed by ETL there no risks to have same gids in different region partitions. I considered simple partitioned table w/o any keys but I’d believed there is a solutions with keys that’s why I’m seeking the clue.

Thanks.

Andrew.

 

From: Marc Millas <marc.millas@mokadb.com>
Sent: Tuesday, March 01, 2022 7:29 PM
To: Andrew Zakharov <Andrew898@mail.ru>
Cc: pgsql-performance@lists.postgresql.org
Subject: Re: Simple task with partitioning which I can't realize

 

Hi,

 

is there any chance (risk ?) that a given gid be present in more than one region ?

if not (or if you implement it via a dedicated, non partition table), 

 

you may create a simple table partitioned by region, and create unique indexes for each partition.

this is NOT equivalent to a unique constraint at global table level, of course.

Marc MILLAS

Senior Architect

+33607850334

www.mokadb.com

 

 

 

On Tue, Mar 1, 2022 at 4:37 PM Andrew Zakharov <Andrew898@mail.ru> wrote:

Hello all –

I have a task which is simple at the first look. I have a table which contains hierarchy of address objects starting with macro region end ends with particular buildings. You can imagine how big is it.

Here is short sample of table declaration:

 

create table region_hierarchy(

  gid uuid not null default uuid_generate_v1mc(),

  parent_gid uuid null,

  region_code int2,

  …

    constraint pk_region_hierarchy primary key (gid),

    constraint fk_region_hierarchy_region_hierarchy_parent foreign key (parent_gid) references region_hierarchy(gid)

);

 

Being an Oracle specialist, I planned to using same declarative partitioning by list on the region_code field as I did in Oracle database. I’ve carefully looked thru docs/faqs/google/communities and found out that I must include “gid” field into partition key because a primary key field. Thus partition method “by list” is not appropriate method in this case and “by range” either. What I have left from partition methods? Hash? How can I create partitions by gid & region_code by hash? Feasible? Will it be working properly (with partition pruning) when search criteria is by region_code only? Same problem appears when there is simple serial “id” used as primary identifier. Removing all constraints is not considered. I understand that such specific PostgreSQL partitioning implementation has done by tons of reasons but how I can implement partitioning for my EASY case? I see the only legacy inheritance is left, right? Very sad if it’s true.

Your advices are very important.

Thanks in advance.

Andrew.