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parts

Contains information about parts of MergeTree tables.

Each row describes one data part.

Columns:

  • partition (String) – The partition name. To learn what a partition is, see the description of the ALTER query.

    Formats:

    • YYYYMM for automatic partitioning by month.
    • any_string when partitioning manually.
  • name (String) – Name of the data part.

  • part_type (String) — 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 table.

  • 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 by the index granularity (usually 8192) (this hint does not work for adaptive granularity).

  • 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.

  • primary_key_size (UInt64) – The amount of memory (in bytes) used by primary key values in the primary.idx/cidx file on disk.

  • marks_bytes (UInt64) – The size of the file with marks.

  • secondary_indices_compressed_bytes (UInt64) – 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) – 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) – The size of the file with marks for secondary indices.

  • 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 does not exist. For more details, see 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_name (String) – Name of a disk that stores the data part.

  • hash_of_all_files (String) – sipHash128 of compressed files.

  • hash_of_uncompressed_files (String) – sipHash128 of uncompressed files (files with marks, index file etc.).

  • uncompressed_hash_of_compressed_files (String) – sipHash128 of data in the compressed files as if they were uncompressed.

  • delete_ttl_info_min (DateTime) — The minimum value of the date and time key for TTL DELETE rule.

  • delete_ttl_info_max (DateTime) — The maximum value of the date and time key for TTL DELETE rule.

  • move_ttl_info.expression (Array(String)) — Array of expressions. Each expression defines a TTL MOVE rule.

note

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.

  • move_ttl_info.min (Array(DateTime)) — Array of date and time values. Each element describes the minimum key value for a TTL MOVE rule.

  • move_ttl_info.max (Array(DateTime)) — Array of date and time values. Each element describes the maximum key value for a TTL MOVE rule.

  • bytes (UInt64) – Alias for bytes_on_disk.

  • marks_size (UInt64) – Alias for marks_bytes.

Example

SELECT * FROM system.parts LIMIT 1 FORMAT Vertical;
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