Docs

ByteHouse Cloud Data Warehouse Version

System tables

system.cnch_parts

The system table system.cnch_parts contains information about all stored data parts, covering key attributes such as part storage, state, transactions, and associated tables. It can be used to monitor the part life cycle and troubleshoot data storage problems. It is recommended to use this system table instead of system.parts.

Column names

| | | | \

Field name	Data type	Description
			\
database	String	The database name to which the part belongs.
			\
table	String	The name of the table to which the part belongs.
			\
table_uuid	UUID	The unique UUID identifier of the table to which the part belongs.
			\
partition	String	The partition name where the part is located.
			\
name	String	The name of the part.
			\
chain_depth	UInt64	The version chain length relative to the mutation baseline.
			\
bytes_on_disk	UInt64	The size of the part on disk, in bytes.
			\
rows_count	UInt64	Total number of rows contained in the part.
			\
delete_rows	UInt64	Number of rows marked as deleted in the part.
			\
columns	String	Column information contained in the part.
			\
marks_count	UInt64	Number of marks in the part.
			\
index_granularity	Array(UInt64)	Index granularity array of the part.
			\
commit_time	DateTime	Time when the part is submitted to ByteKV (metadata storage).
			\
kv_commit_time	DateTime	Submission time corresponding to the schema version used by the part.
			\
columns_commit_time	DateTime	Submission time for mutation tasks that do not change the table schema, such as data updates.
			\
mutation_commit_time	DateTime	Submission time for mutation tasks involving table schema changes.
			\
previous_version	UInt64	After a mutation is executed, the new part points to the commit_time of the original part for version tracing.
			\
partition_id	String	The unique identifier (ID) of the partition where the part is located.
			\
bucket_number	UInt64	Bucket hash result of the part.
			\
total_bucket_cnt	UInt64	Total number of buckets.
			\
table_definition_hash	UInt64	Hash value of the table definition.
			\
outdated	UInt8	Whether the part is outdated:	\
			\
		* 1 = outdated;	\
		* 0 = not outdated.
			\
visible	UInt8	Whether the part is visible to queries:	\
			\
		* 1 = visible;	\
		* 0 = not visible.
			\
part_type	Enum8	Part type. Enumeration values include:	\
			\
		* `VisiblePart` (1): visible and active part	\
		* `InvisiblePart` (2): temporary part that is not visible	\
		* `Tombstone` (3): tombstone part (marked as deleted)	\
		* `DroppedPart` (4): deleted part
			\
data_type	String	Data type.
			\
layout_type	String	Storage layout type.
			\
part_id	UUID	The unique UUID identifier of the part.
			\
commit_ts	UInt64	Commit timestamp of the part in the transaction.
			\
end_ts	UInt64	Timestamp when the part is marked as unavailable, such as when triggered by truncate or merge operations.
			\
last_modification_time	DateTime	Last time the part was modified.
			\
active	UInt8	Whether the part is available:	\
			\
		* 1 = available;	\
		* 0 = not available.
			\
bytes	UInt64	Logical data size of the part, in bytes.
			\
rows	UInt64	Logical number of rows in the part.

Example

The following example shows how to query the system table system.cnch_parts for the table order_details:

SELECT * 
FROM system.cnch_parts 
WHERE database = 'sales_db'  -- Replace with the database name of the table you want to query 
AND table = 'order_details'; -- Replace with the table name you want to query

Example query results:

Last updated: 2026.03.31 16:19:34

ByteHouse Cloud Data Warehouse Version

Column names #

Example #

Column names

Example