Non-covering range partitions
Kudu supports the use of non-covering range partitions, which can be used to address the following scenarios:
- In the case of time-series data or other schemas which need to account for constantly-increasing primary keys, tablets serving old data will be relatively fixed in size, while tablets receiving new data will grow without bounds.
- In cases where you want to partition data based on its category, such as sales region or product type, without non-covering range partitions you must know all of the partitions ahead of time or manually recreate your table if partitions need to be added or removed, such as the introduction or elimination of a product type.
The following example creates a tablet per year (5 tablets total), for storing log data. The table only accepts data from 2012 to 2016. Keys outside of these ranges will be rejected.
CREATE TABLE sales_by_year ( year INT, sale_id INT, amount INT, PRIMARY KEY (year, sale_id) ) PARTITION BY RANGE (year) ( PARTITION VALUE = 2012, PARTITION VALUE = 2013, PARTITION VALUE = 2014, PARTITION VALUE = 2015, PARTITION VALUE = 2016 ) STORED AS KUDU;
When records start coming in for 2017, they will be rejected. At that point, the
2017range should be added as follows:
In use cases where a rolling window of data retention is required, range partitions may also be dropped. For example, if data from 2012 should no longer be retained, it may be deleted in bulk:
ALTER TABLE sales_by_year ADD RANGE PARTITION VALUE = 2017;
Note that just like dropping a table, this irrecoverably deletes all data stored in the dropped partition.
ALTER TABLE sales_by_year DROP RANGE PARTITION VALUE = 2012;