parts
Contains information about parts of 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:
YYYYMMfor automatic partitioning by month.any_stringwhen 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_partandmin_rows_for_wide_partsettings 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, multiplymarksby the index granularity (usually 8192) (this hint does not 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.primary_key_size(UInt64) – The amount of memory (in bytes) used by primary key values in the primary.idx/cidx file on disk.marks_bytes(UInt64) – The size of the file with marks.secondary_indices_compressed_bytes(UInt64) – Total size of compressed data for secondary indices in the data part. All the auxiliary files (for example, files with marks) are not included.secondary_indices_uncompressed_bytes(UInt64) – Total size of uncompressed data for secondary indices in the data part. All the auxiliary files (for example, files with marks) are not included.secondary_indices_marks_bytes(UInt64) – The size of the file with marks for secondary indices.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 thandata_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 does not exist. For more details, see FREEZE PARTITIONdatabase(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_name(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.
The move_ttl_info.expression array is kept mostly for backward compatibility, now the simplest 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 forbytes_on_disk.marks_size(UInt64) – Alias formarks_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
secondary_indices_compressed_bytes: 58
secondary_indices_uncompressed_bytes: 6
secondary_indices_marks_bytes: 48
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