Re: [pgadmin-hackers] Declarative partitioning in pgAdmin4

On Mon, Jun 5, 2017 at 11:45 AM, Dave Page <dpage@pgadmin.org> wrote:

The former is what I was bleating about when I said we needed to expose partitions to the user. The latter isn't relevant - declarative partitioning in Postgres doesn't use inheritance.

The former is certainly the most interesting.  We do need to expose the partitions but only exposing them individually might be a bit overwhelming. What we found was that the number of partitions users have, (given existing means of leveraging partitions) vary from ~100 up to 10k. Basically what we were thinking about was how we can create a workflow/interface that allows users to modify one or more children at once. Furthermore, it would be nice if we could figure out an easy (easy-ish) way for users to identify the one or more partitions that need to be modified. 

For roll up this pattern seems obvious, identify the n partitions you need/want to combine and then run a job to combine them. 

For other patterns such as creating indexes and such it requires a bit more thought. Generally users described wanting to treat all of the children like a single table (just like Oracle), however, other users described potentially modifying chunks of partitions differently depending on some criterion. This means that users will need to identify the subset they want to optimize and then ideally be able to act on them all at once. 

-- Rob

 

So... it sounds like we're on the right lines :-)

 

For the former, this can be addressed by enabling users to modify one or more child partitions at the same time. For the latter, that is a workflow that might be addressed outside of the create table with partition workflow we're working on currently. 

On Mon, Jun 5, 2017 at 5:21 AM Dave Page <dpage@pgadmin.org> wrote:

On Fri, Jun 2, 2017 at 9:01 AM, Akshay Joshi <akshay.joshi@enterprisedb.com> wrote:

Hi All 

Following are the further implementation updates to support Declarative Partitioning:

• Show all the existing partitions of the parent table in Partitions tab (Refer Existing_Partitions.png)
• Ability to create N partitions and detach existing partitions. Refer (Create_Detach_Partition.png), in this example I have detach two existing partition and create two new partitions.
• Added "Detach Partition" menu to partitions node only and user will be able to detach from there as well. Refer (Detach.png)   

That's looking good to me :-)

 

On Wed, May 24, 2017 at 8:00 PM, Robert Eckhardt <reckhardt@pivotal.io> wrote:

On Wed, May 24, 2017 at 3:35 AM, Akshay Joshi <akshay.joshi@enterprisedb.com> wrote:

   Taking average of two columns is just an example/representation of expression, there is no use case of that. As I am also in learning phase. Below are some use case that I can think of:

• Partitions based on first letter of their username
  

  CREATE TABLE users (
      id             serial not null,
      username       text not null,
      password       text,
      created_on     timestamptz not null,
      last_logged_on timestamptz not null
  )PARTITION BY RANGE ( lower( left( username, 1 ) ) );
  CREATE TABLE users_0
      partition of users (id, primary key (id), unique (username))
      for values from ('a') to ('g');
  CREATE TABLE users_1
      partition of users (id, primary key (id), unique (username))
      for values from ('g') to (unbounded);

•  Partition based on country's sale for each month of an year.

CREATE TABLE public.sales

(

    country text NOT NULL,

    sales bigint NOT NULL,

    saledate date

) PARTITION BY RANGE (country, (extract (YEAR FROM saledate)), (extract(MONTH FROM saledate)))

CREATE TABLE public.sale_usa_2017_jan PARTITION OF sales

    FOR VALUES FROM ('usa', 2017, 01) TO ('usa', 2017, 02);

CREATE TABLE public.sale_india_2017_jan PARTITION OF sales

    FOR VALUES FROM ('india', 2017, 01) TO ('india', 2017, 02);

CREATE TABLE public.sale_uk_2017_jan PARTITION OF sales

    FOR VALUES FROM ('uk', 2017, 01) TO ('uk', 2017, 02);

INSERT INTO sales VALUES ('india', 10000, '2017-1-15');

INSERT INTO sales VALUES ('uk', 20000, '2017-1-08');

INSERT INTO sales VALUES ('usa', 30000, '2017-1-10');

   Apart from above there may be N number of use cases that depends on specific requirement of user. 

Thank you for the example, you are absolutely correct and we were confused. 

Given our new found understanding do you mind if we iterate a bit on the UI/UX?  What we were suggesting with the daily/monthly/yearly drop down was a specific example of an expression. Given that fact that doesn't seem to be required in an MVP, however, I do think a more interactive experience between the definition of the child partitions and the creation of the partitions would be optimal. 

I'm not sure where you are with respect to implementing the UI but I'd love to float some ideas and mock ups past you. 

-- Rob

--

Akshay Joshi

Principal Software Engineer 

Phone: +91 20-3058-9517
Mobile: +91 976-788-8246

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Dave Page

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Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

--

Dave Page
Blog: http://pgsnake.blogspot.com
Twitter: @pgsnake

EnterpriseDB UK: http://www.enterprisedb.com
The Enterprise PostgreSQL Company