Fuse Engine

Introduced or updated: v1.2.617

Databend utilizes the Fuse Engine as its default engine, offering a data management system with a user-friendly interface reminiscent of Git. Users have the ability to effortlessly query data at any given moment and effortlessly restore data to any desired point in time.

Syntax

CREATE TABLE <table_name> (
  <column_definitions>
) [ENGINE = FUSE] 
[CLUSTER BY (<expr> [, <expr>, ...] )] 
[<Options>];

For more details about the CREATE TABLE syntax, see CREATE TABLE.

Parameter	Description
ENGINE	If an engine is not explicitly specified, Databend will automatically default to using the Fuse Engine to create tables, which is equivalent to ENGINE = FUSE.
CLUSTER BY	Specifies the sorting method for data that consists of multiple expressions. For more information, see Cluster Key.
<Options>	The Fuse Engine offers various options (case-insensitive) that allow you to customize the table's properties. See Fuse Engine Options for details. - Separate multiple options with a space. - Use ALTER TABLE OPTION to modify a table's options. - Use SHOW CREATE TABLE to show a table's options.

Fuse Engine Options

The following are the available Fuse Engine options:

Option	Syntax	Description
bloom_index_columns	bloom_index_columns = '<column> [, <column> ...]'	Specifies the columns to be used for the bloom index. The data type of these columns can be Map, Number, String, Date, or Timestamp. If no specific columns are specified, the bloom index is created by default on all supported columns. bloom_index_columns='' disables the bloom indexing.
compression	compression = '<compression>'	Specifies the compression method for the engine. Compression options include lz4, zstd, snappy, or none. The compression method defaults to zstd in object storage and lz4 in file system (fs) storage.
storage_format	storage_format = '<storage_format>'	Specifies how data is stored. By default, the storage_format is set to Parquet, which offers high compression and is ideal for cloud-native object storage. Additionally, the experimental Native format is supported, optimizing memory copy overhead for storage devices like file systems.
snapshot_loc	snapshot_loc = '<snapshot_loc>'	Specifies a location parameter in string format, allowing easy sharing of a table without data copy.
block_size_threshold	block_size_threshold = <n>	Specifies the maximum block size in bytes. Defaults to 104,857,600 bytes.
block_per_segment	block_per_segment = <n>	Specifies the maximum number of blocks in a segment. Defaults to 1,000.
row_per_block	row_per_block = <n>	Specifies the maximum number of rows in a file. Defaults to 1,000,000.
change_tracking	change_tracking = True / False	Setting this option to True in the Fuse Engine allows for tracking changes for a table. Creating a stream for a table will automatically set change_tracking to True and introduce additional hidden columns to the table as change tracking metadata. For more information, see How Stream Works.
data_retention_period_in_hours	data_retention_period_in_hours = <n>	Specifies the number of hours to retain table data. The minimum value is 1 hour. The maximum value is defined by the data_retention_time_in_days_max setting in the databend-query.toml configuration file , or defaults to 2,160 hours (90 days x 24 hours) if not specified.