Re: [pgadmin-hackers] Declarative partitioning in pgAdmin4

To add some interview context - from talking to DBAs, partitioning is the most frequent use case we should account for first. Breaking down child partitions into smaller pieces wasn't something we heard as a need. This is probably not the highest priority work needed now.

We should think about when it would be good to release partitioning for some feedback. Did you already have this planned out?

On Tue, Jun 13, 2017 at 9:46 AM Robert Eckhardt <reckhardt@pivotal.io> wrote:

Akshay,

Have you determined the minimum feature set you are shooting for before you commit this? The reason I ask is that we were thinking that some level of simple automation would probably be nice to make this super useful. 

Basically if you consider a simple example of partitioning 90 days of data by day the manual process of creating the names and to - from fields becomes rather painful. If you couple that with potentially wanting to do list subpartitioning if just multiplies the work. 

If we could get something committed then we could more easily work to define where simple automation makes sense and where it doesn't. 

-- Rob

On Tue, Jun 13, 2017 at 6:59 AM, Akshay Joshi <akshay.joshi@enterprisedb.com> wrote:

Hi All 

For further implementation following task needs to be work upon:

• How to parse and show partitions keys. For example user has created below partitioned table 

CREATE TABLE public.sales

(

    country character varying COLLATE pg_catalog."default" NOT NULL,

    sales bigint,

    saledate date

) PARTITION BY RANGE (country, date_part('year'::text, sale date))

When user open the properties dialog I am not able to figure out how to parse keys(displayed in bold in above example) and show them in our control that we used. For the time being I have hide that control in 'Edit' mode (Refer Attach Partition.png)

• Support of sub partitioning: To implement sub-partitioning, specify the PARTITION BY clause in the commands used to create individual partitions, for example:

• CREATE TABLE measurement_y2006 PARTITION OF measurement    FOR VALUES FROM ('2006-02-01') TO ('2006-03-01')    PARTITION BY RANGE (peaktemp);

           To achieve above I have made some changes in GUI (Refer Sub Partition.png). 

           Complex and challenging part here is "measurement_y2006" is partition of "measurement" and parent table for other partitions too which user can create later. How we will going to show this in browser tree? 

           One option could be

           Tables

             ->measurement(table)

               ->Partitions

                 ->measurement_y2006(Partition of measurement and parent of p1) 

                   ->Partitions

                     ->p1 

• Attach Partitions: To implement attach N partitions I have made some changes in GUI( Refer Attach Partition.png). Attach Partitions control will only be visible in "Edit" mode.

I have only modified the UI changes, there are lots of work needs to be done to complete that.  

Please review the design. Suggestions/Comments are welcome.

  

On Tue, Jun 6, 2017 at 4:30 PM, Robert Eckhardt <reckhardt@pivotal.io> wrote:

On Tue, Jun 6, 2017 at 4:32 AM, Dave Page <dpage@pgadmin.org> wrote:

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

You're thinking Greenplum :-). There is no roll up in PostgreSQL, unless you're thinking we should create such a feature in pgAdmin.

Of course, I have no objection to extending what we do in PG to add GP feature support, but let's start with PG.

No not at all. That was a very specific and consistent pattern described by users leveraging time based range partitions in Postgres. I'm not sure if that same use case will be supported with partitioning as implemented in Postgres 10 but it is a Postgres pattern. 

-- Rob

 

 

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. 

Right.

 

-- 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

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

--

Akshay Joshi

Principal Software Engineer 

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