ClickHouse/docs/en/system_tables/system.parts.md
2018-03-30 03:15:52 +03:00

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system.parts

Contains information about parts of a table in the MergeTree family.

Each row describes one part of the data.

Columns:

  • partition (String) The partition name. YYYYMM format. To learn what a partition is, see the description of the ALTER query.
  • name (String) Name of the data part.
  • active (UInt8) Indicates whether the part is active. If a part is active, it is used in a table; otherwise, it will be 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).
  • marks_size (UInt64) The size of the file with marks.
  • rows (UInt64) The number of rows.
  • bytes (UInt64) The number of bytes when compressed.
  • modification_time (DateTime) The modification time of the directory with the data part. 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_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. If a merge was not performed, level=0.
  • 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.
  • database (String) Name of the database.
  • table (String) Name of the table.
  • engine (String) Name of the table engine without parameters.