Re: [pgadmin-hackers] Declarative partitioning in pgAdmin4

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От Shirley Wang
Тема Re: [pgadmin-hackers] Declarative partitioning in pgAdmin4
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Msg-id CAPG3WN72DS8gQmrFR_nBObYaeMaxiqVuyjsVqHaZR1BT4LDqHg@mail.gmail.com
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Ответ на Re: [pgadmin-hackers] Declarative partitioning in pgAdmin4  (Dave Page <dpage@pgadmin.org>)
Ответы Re: [pgadmin-hackers] Declarative partitioning in pgAdmin4  (Dave Page <dpage@pgadmin.org>)
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Hi!

Here's a summary of the interviews thus far:

DBAs tend to create a partition strategy based on their experience and some alignment on their end users goals (analysts, report writers, and app developers). Once that partition strategy is created, they are usually forced to iterate on that strategy later based on feedback from end users of what the usage pattern are.

We've identified a couple workflows that are key in partitioning based on whether they are maintaining a successful strategy or iterating to improve the strategy.

One workflow is for rollups, which is for maintaining partitions at different granularities as data ages. We've learned that older data is less acted upon than recent data so users group together older data for viewing purposes. The other workflow is for splits, which when users discover that the data isn't granular enough so a single partition is being leveraged too many times. Users need to then reevaluate their strategy and tune partitions. 

To reevaluate strategies, DBAs ask themselves a few questions
- Is the partition stable? 
- Are the queries analysts, report writers, and app developers are writing getting the correct data?
- Are the partitions organized in a way that analysts, report writers, and app developers are able to achieve their goals? (ex. goals for app developer might be fast query while goal for report writer might be ability to get data so they can turn out reports faster. Goals might be conflicting)

There are two needs from DBAs in terms of tuning partitioning strategies (there are more but addressing these two will provide the most value to users). One is to modify one or more child partitions by adding indexes or other such things, and the other is to recreate the parent table because there is inheritance to consider. 

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 




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