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

# 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 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.

-   `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 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` ([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-->