# 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. - `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 "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 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) [Original article](https://clickhouse.com/docs/en/operations/system-tables/parts)