Re: Declarative partitioning in pgAdmin4

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(at)pgadmin(dot)org> wrote:

> On Fri, Jun 2, 2017 at 9:01 AM, Akshay Joshi <
> akshay(dot)joshi(at)enterprisedb(dot)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(at)pivotal(dot)io>
>> wrote:
>>
>>>
>>>
>>> On Wed, May 24, 2017 at 3:35 AM, Akshay Joshi <
>>> akshay(dot)joshi(at)enterprisedb(dot)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 <+91%2020%203058%209517>Mobile: +91 976-788-8246
>> <+91%2097678%2088246>*
>>
>>
>> --
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>>
>
>
> --
> Dave Page
>
> Blog: http://pgsnake.blogspot.com
> Twitter: @pgsnake
>
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>