Feature Support: Data Distribution

This document outlines the partitioning and bucketing features supported by StarRocks.

Supported table types

• Bucketing

  Hash Bucketing is supported in all table types. Random Bucketing (from v3.1 onwards) is supported only in Duplicate Key tables.

• Partitioning

  Expression Partitioning (from v3.1 onwards), Range Partitioning, and List Partitioning (from v3.1 onwards) are supported in all table types.

Bucketing

Feature	Key point	Support status	Note
Bucketing strategy	Hash Bucketing	Yes
	Random Bucketing	Yes (v3.1+)	Random Bucketing is supported only in Duplicate Key tables. From v3.2, StarRocks supports dynamically adjusting the number of tablets to create according to cluster information and the data size.
Bucket Key data type	Date, Integer, String	Yes
Bucket number	Automatically set the number of buckets	Yes (v3.0+)	Automatically determined by the number of BE nodes or the data volume of the largest historical partition. The logic has been optimized separately for partitioned tables and non-partitioned tables in later versions.
	Dynamic increase of the Bucket number for Random Bucketing	Yes (v3.2+)

Partitioning

Feature	Key point	Support status	Note
Partitioning strategy	Expression Partitioning	Yes (v3.1+)	Including Partitioning based on a time function expression (since v3.0) and Partitioning based on the column expression (since v3.1) Supported time functions: date_trunc, time_slice
	Range Partitioning	Yes (v3.2+)	Since v3.3.0, three specific time functions can be used for Partition Keys: from_unixtime, from_unixtime_ms, str2date, substr/substring.
	List Partitioning	Yes (v3.1+)
Partition Key data type	Date, Integer, Boolean	Yes
	String	Yes	Only Expression Partitioning and List Partitioning support String-type Partition Key. Range Partitioning does not support String-type Partition Key. You need to use str2date to transform the column to date types.

Differences between partitioning strategies

	Expression Partitioning		Range Partitioning	List Partitioning
	Time function expression-based Partitioning	Column expression-based Partitioning
Data type	Date (DATE/DATETIME)	String (except BINARY) Date (DATE/DATETIME) Integer and Boolean	String (except BINARY) [1] Date or timestamp [1] Integer	String (except BINARY) Date (DATE/DATETIME) Integer and Boolean
Support for multiple Partition Keys	/ (Only supports one date-type Partition Key)	Yes	Yes	Yes
Support Null values for Partition Keys	Yes	/ [2]	Yes	/ [2]
Manual creation of partitions before data loading	/ [3]	/ [3]	Yes if the partitions are manually created in batch No if the dynamic partitioning strategy is adopted	Yes
Automatic creation of partitions while data loading	Yes	Yes	/	/

note

• [1]: You need to use from_unixtime, str2date or other time functions to transform the column to date types.
• [2]: Null values will be supported in Partition Keys for List Partitioning from v3.3.3 onwards.
• [3]: Partitions are automatically created.

For detailed comparisons between List Partitioning and Expression Partitioning, refer to Comparison between list partitioning and expression partitioning.