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# system.parts {#system_tables-parts}
# 系统。零件 {#system_tables-parts}
此系统表包含 [MergeTree](../../engines/table-engines/mergetree-family/mergetree.md) 表分区的相关信息。
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。
每一行描述一个数据分区。
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。
- `partition` ([String](../../sql-reference/data-types/string.md)) 分区名称。请参阅 [ALTER](../../sql-reference/statements/alter/index.md#query_language_queries_alter) 查询的说明,来了解什么是分区
格式:
- `YYYYMM` 用于按月自动分区。
- `any_string` 手动分区时。
- `any_string` 手动分区时,是其他格式的字符串
- `name` (`String`) Name of the data part.
- `name` ([String](../../sql-reference/data-types/string.md)) 数据分区的名称。
- `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.
- `part_type` ([String](../../sql-reference/data-types/string.md)) — 数据分区的存储格式。
- `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
可能的值:
- `rows` (`UInt64`) The number of rows.
- `Wide` — 每一列在文件系统中的一个单独文件中存储。
- `Compact` — 所有列在文件系统中的一个文件中存储。
- `bytes_on_disk` (`UInt64`) Total size of all the data part files in bytes.
数据存储格式由 [MergeTree](../../engines/table-engines/mergetree-family/mergetree.md) 表的 `min_bytes_for_wide_part``min_rows_for_wide_part` 控制。
- `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.
- `active` ([UInt8](../../sql-reference/data-types/int-uint.md)) 指示数据分区是否处于活动状态的标志。如果数据分区处于活动状态,则此数据正在被表使用。反之,则不活跃(deleted)。合并后仍会保留非活跃的数据分区。
- `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` ([UInt64](../../sql-reference/data-types/int-uint.md)) 标记数。要获得数据分区中的大致行数:使用`marks`(标记数)乘以索引粒度(通常为 8192)。不适用于自适应颗粒度。
- `marks_bytes` (`UInt64`) The size of the file with marks.
- `rows` ([UInt64](../../sql-reference/data-types/int-uint.md)) 行数.
- `modification_time` (`DateTime`) The time the directory with the data part was modified. This usually corresponds to the time of data part creation.\|
- `bytes_on_disk` ([UInt64](../../sql-reference/data-types/int-uint.md)) 数据总大小(以字节为单位)。
- `remove_time` (`DateTime`) The time when the data part became inactive.
- `data_compressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) 数据分区中压缩数据的总大小。不包括所有辅助文件(例如,带有标记的文件)。
- `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.
- `data_uncompressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) 数据分区中未压缩数据的总大小。不包括所有辅助文件(例如,带有标记的文件)。
- `min_date` (`Date`) The minimum value of the date key in the data part.
- `marks_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) 带有标记的文件的大小。
- `max_date` (`Date`) The maximum value of the date key in the data part.
- `secondary_indices_compressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) 数据分区中二级索引的压缩数据总大小。所有的辅助文件(例如,带有标记的文件)都不包括在内。
- `min_time` (`DateTime`) The minimum value of the date and time key in the data part.
- `secondary_indices_uncompressed_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) 数据分区中二级索引的未压缩数据的总大小。所有的辅助文件(例如,带有标记的文件)都不包括在内。
- `max_time`(`DateTime`) The maximum value of the date and time key in the data part.
- `secondary_indices_marks_bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) 带标记的二级索引的文件大小。
- `partition_id` (`String`) ID of the partition.
- `modification_time` ([DateTime](../../sql-reference/data-types/datetime.md)) 包含数据分区的目录被修改的时间。这通常对应于数据部分创建的时间。
- `min_block_number` (`UInt64`) The minimum number of data parts that make up the current part after merging.
- `remove_time` ([DateTime](../../sql-reference/data-types/datetime.md)) 数据分区变为非活动状态的时间。
- `max_block_number` (`UInt64`) The maximum number of data parts that make up the current part after merging.
- `refcount` ([UInt32](../../sql-reference/data-types/int-uint.md)) 使用数据部分的位置数。大于 2 的值表示数据部分用于查询或是用于合并。
- `level` (`UInt32`) Depth of the merge tree. Zero means that the current part was created by insert rather than by merging other parts.
- `min_date` ([Date](../../sql-reference/data-types/date.md)) 数据部分中日期键的最小值。
- `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`).
- `max_date` ([Date](../../sql-reference/data-types/date.md)) 数据部分中日期键的最大值。
- `primary_key_bytes_in_memory` (`UInt64`) The amount of memory (in bytes) used by primary key values.
- `min_time` ([DateTime](../../sql-reference/data-types/datetime.md)) 数据部分中日期和时间键的最小值。
- `primary_key_bytes_in_memory_allocated` (`UInt64`) The amount of memory (in bytes) reserved for primary key values.
- `max_time`([DateTime](../../sql-reference/data-types/datetime.md)) 数据部分中日期和时间键的最大值。
- `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)
- `partition_id` ([String](../../sql-reference/data-types/string.md)) 分区的 ID。
- `database` (`String`) Name of the database.
- `min_block_number` ([UInt64](../../sql-reference/data-types/int-uint.md)) 合并后构成当前部分的最小数据部分数量。
- `table` (`String`) Name of the table.
- `max_block_number` ([UInt64](../../sql-reference/data-types/int-uint.md)) 合并后构成当前部分的最大数据部分数量。
- `engine` (`String`) Name of the table engine without parameters.
- `level` ([UInt32](../../sql-reference/data-types/int-uint.md)) 合并树的深度。值为 0 表示该分区是通过插入创建的,而不是通过合并创建的。
- `path` (`String`) Absolute path to the folder with data part files.
- `data_version` ([UInt64](../../sql-reference/data-types/int-uint.md)) 用于确定应将哪些订正(mutations)应用于数据部分(版本高于 `data_version` 的订正(mutations))的数字。
- `disk` (`String`) Name of a disk that stores the data part.
- `primary_key_bytes_in_memory` ([UInt64](../../sql-reference/data-types/int-uint.md)) 主键值使用的内存量(以字节为单位)。
- `hash_of_all_files` (`String`) [sipHash128](../../sql-reference/functions/hash-functions.md#hash_functions-siphash128) 的压缩文件
- `primary_key_bytes_in_memory_allocated` ([UInt64](../../sql-reference/data-types/int-uint.md)) 为主键值保留的内存量(以字节为单位)
- `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。).
- `is_frozen` ([UInt8](../../sql-reference/data-types/int-uint.md)) 显示分区数据备份存在的标志。1备份存在。0备份不存在。更多细节见 [FREEZE PARTITION](../../sql-reference/statements/alter/partition.md#alter_freeze-partition)。
- `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
- `database` ([String](../../sql-reference/data-types/string.md)) 数据库的名称
- `bytes` (`UInt64`) Alias for `bytes_on_disk`.
- `table` ([String](../../sql-reference/data-types/string.md)) 表的名称。
- `marks_size` (`UInt64`) Alias for `marks_bytes`.
- `engine` ([String](../../sql-reference/data-types/string.md)) 不带参数的表引擎名称。
- `path` ([String](../../sql-reference/data-types/string.md)) 包含数据部分文件的文件夹的绝对路径。
- `disk` ([String](../../sql-reference/data-types/string.md)) 存储数据部分的磁盘的名称。
- `hash_of_all_files` ([String](../../sql-reference/data-types/string.md)) 压缩文件的 [sipHash128](../../sql-reference/functions/hash-functions.md#hash_functions-siphash128)。
- `hash_of_uncompressed_files` ([String](../../sql-reference/data-types/string.md)) 未压缩文件(带有标记的文件、索引文件等)的 [sipHash128](../../sql-reference/functions/hash-functions.md#hash_functions-siphash128)。
- `uncompressed_hash_of_compressed_files` ([String](../../sql-reference/data-types/string.md)) 压缩文件中的数据(没有压缩时)的 [sipHash128](../../sql-reference/functions/hash-functions.md#hash_functions-siphash128)。
- `delete_ttl_info_min` ([DateTime](../../sql-reference/data-types/datetime.md)) — [TTL DELETE 规则](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl) 的日期和时间键的最小值。
- `delete_ttl_info_max` ([DateTime](../../sql-reference/data-types/datetime.md)) — [TTL DELETE 规则](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl) 的日期和时间键的最大值。
- `move_ttl_info.expression` ([Array](../../sql-reference/data-types/array.md)([String](../../sql-reference/data-types/string.md))) — 表达式的数组。 每个表达式定义一个 [TTL MOVE 规则](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl).
!!! note "警告"
保留 `move_ttl_info.expression` 数组主要是为了向后兼容,现在检查 `TTL MOVE` 规则最简单的方法是使用 `move_ttl_info.min``move_ttl_info.max` 字段。
- `move_ttl_info.min` ([Array](../../sql-reference/data-types/array.md)([DateTime](../../sql-reference/data-types/datetime.md))) — 日期值和时间值的数组。数组中的每个元素都描述了一个 [TTL MOVE rule](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl) 的最小键值。
- `move_ttl_info.max` ([Array](../../sql-reference/data-types/array.md)([DateTime](../../sql-reference/data-types/datetime.md))) — 日期值和时间值的数组。数组中的每个元素都描述了一个 [TTL MOVE rule](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl) 的最大键值。
- `bytes` ([UInt64](../../sql-reference/data-types/int-uint.md)) `bytes_on_disk`的别名。
- `marks_size` ([UInt64](../../sql-reference/data-types/int-uint.md)) `marks_bytes`的别名。
**示例**
``` 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: []
```
**另请参阅**
- [MergeTree(合并树)家族](../../engines/table-engines/mergetree-family/mergetree.md)
- [列和表的 TTL](../../engines/table-engines/mergetree-family/mergetree.md#table_engine-mergetree-ttl)
[原文](https://clickhouse.com/docs/zh/operations/system-tables/parts) <!--hide-->