ClickHouse/docs/zh/operations/system-tables/parts.md

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2020-06-22 08:45:22 +00:00
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# 系统。零件 {#system_tables-parts}
包含有关的部分信息 [MergeTree](../../engines/table-engines/mergetree-family/mergetree.md) 桌子
每行描述一个数据部分。
列:
- `partition` (String) The partition name. To learn what a partition is, see the description of the [ALTER](../../sql-reference/statements/alter.md#query_language_queries_alter) 查询。
格式:
- `YYYYMM` 用于按月自动分区。
- `any_string` 手动分区时。
- `name` (`String`) Name of the data part.
- `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` 通过索引粒度通常为8192此提示不适用于自适应粒度
- `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](../../sql-reference/statements/alter.md#alter_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](../../sql-reference/functions/hash-functions.md#hash_functions-siphash128) 的压缩文件。
- `hash_of_uncompressed_files` (`String`) [sipHash128](../../sql-reference/functions/hash-functions.md#hash_functions-siphash128) 未压缩的文件(带标记的文件,索引文件等。).
- `uncompressed_hash_of_compressed_files` (`String`) [sipHash128](../../sql-reference/functions/hash-functions.md#hash_functions-siphash128) 压缩文件中的数据,就好像它们是未压缩的。
- `bytes` (`UInt64`) Alias for `bytes_on_disk`.
- `marks_size` (`UInt64`) Alias for `marks_bytes`.