Managing Partitions – Range

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Let us understand how to manage partitions for the table users_range_part.

  • All users data created in a specific year should go to the respective partition created.

  • For example, all users data created in the year of 2016 should go to users_range_part_2016.

  • We can add partition to existing partitioned table using CREATE TABLE partition_name PARTITION OF table_name.

  • We can have a partition for default values so that all the data that does not satisfy the partition condition can be added to it.

  • We can have a partition for specific range of values using FOR VALUES FROM (from_value) TO (to_value) as part of CREATE TABLE partition_name PARTITION OF table_name.

  • Once partitions are added, we can insert data into the partitioned table.

Note

Here is how we can create partition for default values for a range partitioned table users_range_part.

%load_ext sql

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The sql extension is already loaded. To reload it, use:
  %reload_ext sql

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%env DATABASE_URL=postgresql://itversity_sms_user:sms_password@localhost:5432/itversity_sms_db

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env: DATABASE_URL=postgresql://itversity_sms_user:sms_password@localhost:5432/itversity_sms_db

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%%sql

CREATE TABLE users_range_part_default
PARTITION OF users_range_part DEFAULT

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
Done.

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[]

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%%sql

CREATE TABLE users_range_part_2016
PARTITION OF users_range_part
FOR VALUES FROM ('2016-01-01') TO ('2016-12-31')

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
Done.

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[]

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Error

As there is a overlap between the previous partition and below one, command to create partition for data ranging from 2016-01-01 till 2017-12-31 will fail.

%%sql

CREATE TABLE users_range_part_2017
PARTITION OF users_range_part
FOR VALUES FROM ('2016-01-01') TO ('2017-12-31')

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
(psycopg2.errors.InvalidObjectDefinition) partition "users_range_part_2017" would overlap partition "users_range_part_2016"

[SQL: CREATE TABLE users_range_part_2017 PARTITION OF users_range_part
FOR VALUES FROM ('2016-01-01') TO ('2017-12-31')]
(Background on this error at: http://sqlalche.me/e/13/f405)

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Note

This is how we can create partitions for the years 201720182019 etc

%%sql

CREATE TABLE users_range_part_2017
PARTITION OF users_range_part
FOR VALUES FROM ('2017-01-01') TO ('2017-12-31')

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
Done.

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[]

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%%sql

CREATE TABLE users_range_part_2018
PARTITION OF users_range_part
FOR VALUES FROM ('2018-01-01') TO ('2018-12-31')

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
Done.

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[]

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%%sql

CREATE TABLE users_range_part_2019
PARTITION OF users_range_part
FOR VALUES FROM ('2019-01-01') TO ('2019-12-31')

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
Done.

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[]

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%%sql

CREATE TABLE users_range_part_2020
PARTITION OF users_range_part
FOR VALUES FROM ('2020-01-01') TO ('2020-12-31')

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
Done.

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[]

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%%sql

INSERT INTO users_range_part 
    (user_first_name, user_last_name, user_email_id, created_dt)
VALUES 
    ('Scott', 'Tiger', 'scott@tiger.com', '2018-10-01'),
    ('Donald', 'Duck', 'donald@duck.com', '2019-02-10'),
    ('Mickey', 'Mouse', 'mickey@mouse.com', '2017-06-22')

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
3 rows affected.

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[]

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%%sql

SELECT user_first_name, user_last_name, user_email_id, created_dt
FROM users_range_part_default

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
0 rows affected.

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user_first_name user_last_name user_email_id created_dt
%%sql

SELECT user_first_name, user_last_name, user_email_id, created_dt
FROM users_range_part_2017

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
1 rows affected.

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user_first_name user_last_name user_email_id created_dt
Mickey Mouse mickey@mouse.com 2017-06-22
%%sql

SELECT user_first_name, user_last_name, user_email_id, created_dt
FROM users_range_part_2018

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
1 rows affected.

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user_first_name user_last_name user_email_id created_dt
Scott Tiger scott@tiger.com 2018-10-01
%%sql

SELECT user_first_name, user_last_name, user_email_id, created_dt
FROM users_range_part_2019

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
1 rows affected.

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user_first_name user_last_name user_email_id created_dt
Donald Duck donald@duck.com 2019-02-10
%%sql

SELECT user_first_name, user_last_name, user_email_id, created_dt
FROM users_range_part_2020

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 * postgresql://itversity_sms_user:***@localhost:5432/itversity_sms_db
0 rows affected.

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user_first_name