Fuse Engine

Introduced or updated: v1.2.223

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.

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Syntax

CREATE TABLE table_name (
  column_name1 column_type1,
  column_name2 column_type2,
  ...
) [ENGINE = FUSE] [CLUSTER BY(<expr> [, <expr>, ...] )] [Options];

For more information about the CREATE TABLE command, see CREATE TABLE.

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

The CLUSTER BY parameter specifies the sorting method for data that consists of multiple expressions, which is useful during compaction or recluster. A suitable CLUSTER BY parameter can significantly accelerate queries.

Options

The Fuse Engine offers the following options (case-insensitive) that enable you to customize the engine's functionality even further. To modify the options of an existing table, use the ALTER TABLE OPTION command.

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 = '<block_size_threshold>'	Specifies the maximum block size in bytes. Defaults to 104,857,600 bytes.
block_per_segment	block_per_segment = '<block_per_segment>'	Specifies the maximum number of blocks in a segment. Defaults to 1,000.
row_per_block	row_per_block = '<row_per_block>'	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.