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system.projection_parts

This table contains information about projection parts for tables of the MergeTree family.

Columns​

  • partition (String) — The partition name.
  • name (String) — Name of the data part.
  • part_type (String) — The data part storing format. Possible Values: Wide (a file per column) and Compact (a single file for all columns).
  • parent_name (String) — The name of the source (parent) data part.
  • parent_uuid (UUID) — The UUID of the source (parent) data part.
  • parent_part_type (String) — The source (parent) data part storing format.
  • 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 about to be deleted. Inactive data parts appear after merging and mutating operations.
  • 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.
  • marks_bytes (UInt64) — The size of the file with marks.
  • parent_marks (UInt64) — The number of marks in the source (parent) part.
  • parent_rows (UInt64) — The number of rows in the source (parent) part.
  • parent_bytes_on_disk (UInt64) — Total size of all the source (parent) data part files in bytes.
  • parent_data_compressed_bytes (UInt64) — Total size of compressed data in the source (parent) data part.
  • parent_data_uncompressed_bytes (UInt64) — Total size of uncompressed data in the source (parent) data part.
  • parent_marks_bytes (UInt64) — The size of the file with marks in the source (parent) data part.
  • 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 (Int64) — The minimum number of data parts that make up the current part after merging.
  • max_block_number (Int64) — 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.
  • database (String) — Name of the database.
  • table (String) — Name of the table.
  • engine (String) — Name of the table engine without parameters.
  • disk_name (String) — Name of a disk that stores the data part.
  • path (String) — Absolute path to the folder with data part files.
  • 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.
  • 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.
  • default_compression_codec (String) — The name of the codec used to compress this data part (in case when there is no explicit codec for columns).
  • recompression_ttl_info.expression (Array(String)) — The TTL expression.
  • recompression_ttl_info.min (Array(DateTime)) — The minimum value of the calculated TTL expression within this part. Used to understand whether we have at least one row with expired TTL.
  • recompression_ttl_info.max (Array(DateTime)) — The maximum value of the calculated TTL expression within this part. Used to understand whether we have all rows with expired TTL.
  • group_by_ttl_info.expression (Array(String)) — The TTL expression.
  • group_by_ttl_info.min (Array(DateTime)) — The minimum value of the calculated TTL expression within this part. Used to understand whether we have at least one row with expired TTL.
  • group_by_ttl_info.max (Array(DateTime)) — The maximum value of the calculated TTL expression within this part. Used to understand whether we have all rows with expired TTL.
  • rows_where_ttl_info.expression (Array(String)) — The TTL expression.
  • rows_where_ttl_info.min (Array(DateTime)) — The minimum value of the calculated TTL expression within this part. Used to understand whether we have at least one row with expired TTL.
  • rows_where_ttl_info.max (Array(DateTime)) — The maximum value of the calculated TTL expression within this part. Used to understand whether we have all rows with expired TTL.
  • is_broken (UInt8) — Whether projection part is broken
  • exception_code (Int32) — Exception message explaining broken state of the projection part
  • exception (String) — Exception code explaining broken state of the projection part