Besides partition, the bucket is another technique to cluster datasets into more manageable parts to optimize query performance. Different from a partition, a bucket corresponds to segments of files in HDFS. For example, the employee_partitioned table from the previous section uses year and month as the top-level partition. If there is a further request to use employee_id as the third level of partition, it creates many partition directories. For instance, we can bucket the employee_partitioned table using employee_id as a bucket column. The value of this column will be hashed by a user-defined number of buckets. The records with the same employee_id will always be stored in the same bucket (segment of files). The bucket columns are defined by CLUSTERED BY keywords. It is quite different from partition columns since partition columns refer to the directory, while bucket...
Germany
Slovakia
Canada
Brazil
Singapore
Hungary
Philippines
Mexico
Thailand
Ukraine
Luxembourg
Estonia
Lithuania
Norway
Chile
United States
Great Britain
India
Spain
South Korea
Ecuador
Colombia
Taiwan
Switzerland
Indonesia
Cyprus
Denmark
Finland
Poland
Malta
Czechia
New Zealand
Austria
Turkey
France
Sweden
Italy
Egypt
Belgium
Portugal
Slovenia
Ireland
Romania
Greece
Argentina
Malaysia
South Africa
Netherlands
Bulgaria
Latvia
Australia
Japan
Russia