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ClickHouse/docs/en/operations/system-tables/parts.md
Anna a6fb067a75
DOCSUP-1915: Split system-table.md into separate files. (#13160) 
* Corrected en files

* Split system-tables.md into separate files

* Fixed links.

* Fixed links.

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* Add ref to original article

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* Add toc_folder_title and translate

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* Update run.sh, thanks @azat

Co-authored-by: Anna Devyatova <annadevyatova@yandex-team.ru>
Co-authored-by: Sergei Shtykov <bayonet@yandex-team.ru>
Co-authored-by: alexey-milovidov <milovidov@yandex-team.ru>
2020-08-06 11:50:29 +03:00

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# system.parts {#system_tables-parts}
Contains information about parts of [MergeTree](../../engines/table-engines/mergetree-family/mergetree.md) tables.
Each row describes one data part.
Columns:
- `partition` ([String](../../sql-reference/data-types/string.md)) – The partition name. To learn what a partition is, see the description of the [ALTER](../../sql-reference/statements/alter/index.md#query_language_queries_alter) query.
Formats:
- `YYYYMM` for automatic partitioning by month.
- `any_string` when partitioning manually.
- `name` ([String](../../sql-reference/data-types/string.md)) – Name of the data part.
- `part_type` ([String](../../sql-reference/data-types/string.md)) — 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](../../engines/table-engines/mergetree-family/mergetree.md) table.
- `active` ([UInt8](../../sql-reference/data-types/int-uint.md)) – 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](../../sql-reference/data-types/int-uint.md)) – 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](../../sql-reference/data-types/int-uint.md)) – The number of rows.
- `bytes_on_disk` ([UInt64](../../sql-reference/data-types/int-uint.md)) – Total size of all the data part files in bytes.
- `data_compressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) – 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](../../sql-reference/data-types/int-uint.md)) – Total size of uncompressed data in the data part. All the auxiliary files (for example, files with marks) are not included.
- `marks_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) – The size of the file with marks.
- `modification_time` ([DateTime](../../sql-reference/data-types/datetime.md)) – The time the directory with the data part was modified. This usually corresponds to the time of data part creation.
- `remove_time` ([DateTime](../../sql-reference/data-types/datetime.md)) – The time when the data part became inactive.
- `refcount` ([UInt32](../../sql-reference/data-types/int-uint.md)) – 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](../../sql-reference/data-types/date.md)) – The minimum value of the date key in the data part.
- `max_date` ([Date](../../sql-reference/data-types/date.md)) – The maximum value of the date key in the data part.
- `min_time` ([DateTime](../../sql-reference/data-types/datetime.md)) – The minimum value of the date and time key in the data part.
- `max_time`([DateTime](../../sql-reference/data-types/datetime.md)) – The maximum value of the date and time key in the data part.
- `partition_id` ([String](../../sql-reference/data-types/string.md)) – ID of the partition.
- `min_block_number` ([UInt64](../../sql-reference/data-types/int-uint.md)) – The minimum number of data parts that make up the current part after merging.
- `max_block_number` ([UInt64](../../sql-reference/data-types/int-uint.md)) – The maximum number of data parts that make up the current part after merging.
- `level` ([UInt32](../../sql-reference/data-types/int-uint.md)) – Depth of the merge tree. Zero means that the current part was created by insert rather than by merging other parts.
- `data_version` ([UInt64](../../sql-reference/data-types/int-uint.md)) – 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](../../sql-reference/data-types/int-uint.md)) – The amount of memory (in bytes) used by primary key values.
- `primary_key_bytes_in_memory_allocated` ([UInt64](../../sql-reference/data-types/int-uint.md)) – The amount of memory (in bytes) reserved for primary key values.
- `is_frozen` ([UInt8](../../sql-reference/data-types/int-uint.md)) – 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](../../sql-reference/statements/alter/partition.md#alter_freeze-partition)
- `database` ([String](../../sql-reference/data-types/string.md)) – Name of the database.
- `table` ([String](../../sql-reference/data-types/string.md)) – Name of the table.
- `engine` ([String](../../sql-reference/data-types/string.md)) – Name of the table engine without parameters.
- `path` ([String](../../sql-reference/data-types/string.md)) – Absolute path to the folder with data part files.
- `disk` ([String](../../sql-reference/data-types/string.md)) – Name of a disk that stores the data part.
- `hash_of_all_files` ([String](../../sql-reference/data-types/string.md)) – [sipHash128](../../sql-reference/functions/hash-functions.md#hash_functions-siphash128) of compressed files.
- `hash_of_uncompressed_files` ([String](../../sql-reference/data-types/string.md)) – [sipHash128](../../sql-reference/functions/hash-functions.md#hash_functions-siphash128) of uncompressed files (files with marks, index file etc.).
- `uncompressed_hash_of_compressed_files` ([String](../../sql-reference/data-types/string.md)) – [sipHash128](../../sql-reference/functions/hash-functions.md#hash_functions-siphash128) of data in the compressed files as if they were uncompressed.
- `delete_ttl_info_min` ([DateTime](../../sql-reference/data-types/datetime.md)) — The minimum value of the date and time key for [TTL DELETE rule](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl).
- `delete_ttl_info_max` ([DateTime](../../sql-reference/data-types/datetime.md)) — The maximum value of the date and time key for [TTL DELETE rule](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl).
- `move_ttl_info.expression` ([Array](../../sql-reference/data-types/array.md)([String](../../sql-reference/data-types/string.md))) — Array of expressions. Each expression defines a [TTL MOVE rule](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl).
!!! note "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](../../sql-reference/data-types/array.md)([DateTime](../../sql-reference/data-types/datetime.md))) — Array of date and time values. Each element describes the minimum key value for a [TTL MOVE rule](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl).
- `move_ttl_info.max` ([Array](../../sql-reference/data-types/array.md)([DateTime](../../sql-reference/data-types/datetime.md))) — Array of date and time values. Each element describes the maximum key value for a [TTL MOVE rule](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl).
- `bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) – Alias for `bytes_on_disk`.
- `marks_size` ([UInt64](../../sql-reference/data-types/int-uint.md)) – Alias for `marks_bytes`.
**Example**
``` sql
SELECT * FROM system.parts LIMIT 1 FORMAT Vertical;
```
``` text
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**
- [MergeTree family](../../engines/table-engines/mergetree-family/mergetree.md)
- [TTL for Columns and Tables](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl)
[Original article](https://clickhouse.tech/docs/en/operations/system_tables/parts) <!--hide-->
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