MergeTree tables.
Each row describes one data part.
Columns:
partition
(String) – The partition name. To learn what a partition is, see the description of the ALTER query.
Formats:
YYYYMM
for automatic partitioning by month.any_string
when partitioning manually.name
(String) – Name of the data part.
part_type
(String) — The data part storing format.
Possible Values:
Wide
— Each column is stored in a separate file in a filesystem. Compact
— All columns are stored in one file in a filesystem. Data storing format is controlled by the min_bytes_for_wide_part
and min_rows_for_wide_part
settings of the MergeTree table.
active
(UInt8) – Flag that indicates whether the data part is active. If a data part is active, it’s used in a table. Otherwise, it’s deleted. Inactive data parts remain after merging.
marks
(UInt64) – The number of marks. To get the approximate number of rows in a data part, multiply marks
by the index granularity (usually 8192) (this hint doesn’t work for adaptive granularity).
rows
(UInt64) – The number of rows.
bytes_on_disk
(UInt64) – Total size of all the data part files in bytes.
data_compressed_bytes
(UInt64) – Total size of compressed data in the data part. All the auxiliary files (for example, files with marks) are not included.
data_uncompressed_bytes
(UInt64) – Total size of uncompressed data in the data part. All the auxiliary files (for example, files with marks) are not included.
marks_bytes
(UInt64) – The size of the file with marks.
modification_time
(DateTime) – The time the directory with the data part was modified. This usually corresponds to the time of data part creation.
remove_time
(DateTime) – The time when the data part became inactive.
refcount
(UInt32) – The number of places where the data part is used. A value greater than 2 indicates that the data part is used in queries or merges.
min_date
(Date) – The minimum value of the date key in the data part.
max_date
(Date) – The maximum value of the date key in the data part.
min_time
(DateTime) – The minimum value of the date and time key in the data part.
max_time
(DateTime) – The maximum value of the date and time key in the data part.
partition_id
(String) – ID of the partition.
min_block_number
(UInt64) – The minimum number of data parts that make up the current part after merging.
max_block_number
(UInt64) – The maximum number of data parts that make up the current part after merging.
level
(UInt32) – Depth of the merge tree. Zero means that the current part was created by insert rather than by merging other parts.
data_version
(UInt64) – Number that is used to determine which mutations should be applied to the data part (mutations with a version higher than data_version
).
primary_key_bytes_in_memory
(UInt64) – The amount of memory (in bytes) used by primary key values.
primary_key_bytes_in_memory_allocated
(UInt64) – The amount of memory (in bytes) reserved for primary key values.
is_frozen
(UInt8) – Flag that shows that a partition data backup exists. 1, the backup exists. 0, the backup doesn’t exist. For more details, see FREEZE PARTITION
database
(String) – Name of the database.
table
(String) – Name of the table.
engine
(String) – Name of the table engine without parameters.
path
(String) – Absolute path to the folder with data part files.
disk
(String) – Name of a disk that stores the data part.
hash_of_all_files
(String) – sipHash128 of compressed files.
hash_of_uncompressed_files
(String) – sipHash128 of uncompressed files (files with marks, index file etc.).
uncompressed_hash_of_compressed_files
(String) – sipHash128 of data in the compressed files as if they were uncompressed.
delete_ttl_info_min
(DateTime) — The minimum value of the date and time key for TTL DELETE rule.
delete_ttl_info_max
(DateTime) — The maximum value of the date and time key for TTL DELETE rule.
move_ttl_info.expression
(Array(String)) — Array of expressions. Each expression defines a TTL MOVE rule.
Warning
The move_ttl_info.expression
array is kept mostly for backward compatibility, now the simpliest way to check TTL MOVE
rule is to use the move_ttl_info.min
and move_ttl_info.max
fields.
move_ttl_info.min
(Array(DateTime)) — Array of date and time values. Each element describes the minimum key value for a TTL MOVE rule.
move_ttl_info.max
(Array(DateTime)) — Array of date and time values. Each element describes the maximum key value for a TTL MOVE rule.
bytes
(UInt64) – Alias for bytes_on_disk
.
marks_size
(UInt64) – Alias for marks_bytes
.
Example
SELECT * FROM system.parts LIMIT 1 FORMAT Vertical;
Row 1:
──────
partition: tuple()
name: all_1_4_1_6
part_type: Wide
active: 1
marks: 2
rows: 6
bytes_on_disk: 310
data_compressed_bytes: 157
data_uncompressed_bytes: 91
marks_bytes: 144
modification_time: 2020-06-18 13:01:49
remove_time: 1970-01-01 00:00:00
refcount: 1
min_date: 1970-01-01
max_date: 1970-01-01
min_time: 1970-01-01 00:00:00
max_time: 1970-01-01 00:00:00
partition_id: all
min_block_number: 1
max_block_number: 4
level: 1
data_version: 6
primary_key_bytes_in_memory: 8
primary_key_bytes_in_memory_allocated: 64
is_frozen: 0
database: default
table: months
engine: MergeTree
disk_name: default
path: /var/lib/clickhouse/data/default/months/all_1_4_1_6/
hash_of_all_files: 2d0657a16d9430824d35e327fcbd87bf
hash_of_uncompressed_files: 84950cc30ba867c77a408ae21332ba29
uncompressed_hash_of_compressed_files: 1ad78f1c6843bbfb99a2c931abe7df7d
delete_ttl_info_min: 1970-01-01 00:00:00
delete_ttl_info_max: 1970-01-01 00:00:00
move_ttl_info.expression: []
move_ttl_info.min: []
move_ttl_info.max: []
See Also
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