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11 KiB
Markdown
170 lines
11 KiB
Markdown
---
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slug: /en/operations/system-tables/parts
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---
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# parts {#system_tables-parts}
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Contains information about parts of [MergeTree](../../engines/table-engines/mergetree-family/mergetree.md) tables.
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Each row describes one data part.
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Columns:
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- `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.
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Formats:
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- `YYYYMM` for automatic partitioning by month.
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- `any_string` when partitioning manually.
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- `name` ([String](../../sql-reference/data-types/string.md)) – Name of the data part.
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- `part_type` ([String](../../sql-reference/data-types/string.md)) — The data part storing format.
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Possible Values:
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- `Wide` — Each column is stored in a separate file in a filesystem.
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- `Compact` — All columns are stored in one file in a filesystem.
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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.
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- `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.
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- `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).
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- `rows` ([UInt64](../../sql-reference/data-types/int-uint.md)) – The number of rows.
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- `bytes_on_disk` ([UInt64](../../sql-reference/data-types/int-uint.md)) – Total size of all the data part files in bytes.
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- `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.
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- `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.
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- `marks_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) – The size of the file with marks.
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- `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.
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- `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.
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- `secondary_indices_marks_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) – The size of the file with marks for secondary indices.
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- `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.
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- `remove_time` ([DateTime](../../sql-reference/data-types/datetime.md)) – The time when the data part became inactive.
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- `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.
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- `min_date` ([Date](../../sql-reference/data-types/date.md)) – The minimum value of the date key in the data part.
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- `max_date` ([Date](../../sql-reference/data-types/date.md)) – The maximum value of the date key in the data part.
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- `min_time` ([DateTime](../../sql-reference/data-types/datetime.md)) – The minimum value of the date and time key in the data part.
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- `max_time`([DateTime](../../sql-reference/data-types/datetime.md)) – The maximum value of the date and time key in the data part.
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- `partition_id` ([String](../../sql-reference/data-types/string.md)) – ID of the partition.
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- `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.
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- `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.
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- `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.
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- `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`).
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- `primary_key_bytes_in_memory` ([UInt64](../../sql-reference/data-types/int-uint.md)) – The amount of memory (in bytes) used by primary key values.
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- `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.
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- `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)
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- `database` ([String](../../sql-reference/data-types/string.md)) – Name of the database.
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- `table` ([String](../../sql-reference/data-types/string.md)) – Name of the table.
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- `engine` ([String](../../sql-reference/data-types/string.md)) – Name of the table engine without parameters.
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- `path` ([String](../../sql-reference/data-types/string.md)) – Absolute path to the folder with data part files.
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- `disk_name` ([String](../../sql-reference/data-types/string.md)) – Name of a disk that stores the data part.
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- `hash_of_all_files` ([String](../../sql-reference/data-types/string.md)) – [sipHash128](../../sql-reference/functions/hash-functions.md/#hash_functions-siphash128) of compressed files.
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- `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.).
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- `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.
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- `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).
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- `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).
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- `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).
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:::note
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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.
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:::
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- `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).
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- `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).
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- `bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) – Alias for `bytes_on_disk`.
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- `marks_size` ([UInt64](../../sql-reference/data-types/int-uint.md)) – Alias for `marks_bytes`.
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**Example**
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``` sql
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SELECT * FROM system.parts LIMIT 1 FORMAT Vertical;
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```
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``` text
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Row 1:
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──────
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partition: tuple()
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name: all_1_4_1_6
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part_type: Wide
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active: 1
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marks: 2
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rows: 6
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bytes_on_disk: 310
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data_compressed_bytes: 157
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data_uncompressed_bytes: 91
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secondary_indices_compressed_bytes: 58
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secondary_indices_uncompressed_bytes: 6
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secondary_indices_marks_bytes: 48
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marks_bytes: 144
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modification_time: 2020-06-18 13:01:49
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remove_time: 1970-01-01 00:00:00
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refcount: 1
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min_date: 1970-01-01
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max_date: 1970-01-01
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min_time: 1970-01-01 00:00:00
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max_time: 1970-01-01 00:00:00
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partition_id: all
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min_block_number: 1
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max_block_number: 4
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level: 1
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data_version: 6
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primary_key_bytes_in_memory: 8
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primary_key_bytes_in_memory_allocated: 64
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is_frozen: 0
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database: default
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table: months
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engine: MergeTree
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disk_name: default
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path: /var/lib/clickhouse/data/default/months/all_1_4_1_6/
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hash_of_all_files: 2d0657a16d9430824d35e327fcbd87bf
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hash_of_uncompressed_files: 84950cc30ba867c77a408ae21332ba29
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uncompressed_hash_of_compressed_files: 1ad78f1c6843bbfb99a2c931abe7df7d
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delete_ttl_info_min: 1970-01-01 00:00:00
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delete_ttl_info_max: 1970-01-01 00:00:00
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move_ttl_info.expression: []
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move_ttl_info.min: []
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move_ttl_info.max: []
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```
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**See Also**
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- [MergeTree family](../../engines/table-engines/mergetree-family/mergetree.md)
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- [TTL for Columns and Tables](../../engines/table-engines/mergetree-family/mergetree.md/#table_engine-mergetree-ttl)
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