system.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:
YYYYMMfor automatic partitioning by month.any_stringwhen partitioning manually.
name(String) – Name of the data part.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, multiplymarksby the index granularity (usually 8192) (this hint doesn’t 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.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 thandata_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 doesn’t exist. For more details, see FREEZE PARTITIONdatabase(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(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.bytes(UInt64) – Alias forbytes_on_disk.marks_size(UInt64) – Alias formarks_bytes.