thevar1able/ClickHouse
1
0
Fork 0
mirror of https://github.com/ClickHouse/ClickHouse.git synced 2024-11-28 02:21:59 +00:00
Code Issues Packages Projects Releases Wiki Activity
13322f1a90
ClickHouse/docs/en/operations/system-tables/parts.md

172 lines
11 KiB
Markdown
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

---
slug: /en/operations/system-tables/parts
---
# 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 does not 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.
- `primary_key_size` ([UInt64](../../sql-reference/data-types/int-uint.md)) – The amount of memory (in bytes) used by primary key values in the primary.idx/cidx file on disk.
- `marks_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) – The size of the file with marks.
- `secondary_indices_compressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) – 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](../../sql-reference/data-types/int-uint.md)) – 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](../../sql-reference/data-types/int-uint.md)) – The size of the file with marks for secondary indices.
- `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 does not 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_name` ([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
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](../../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
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**
- [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)
Reference in New Issue View Git Blame Copy Permalink