system.projection_parts
This table contains information about projection parts for tables of the MergeTree family.
Columns
| Column | Description | Type |
|---|---|---|
partition | The partition name. | String |
name | Name of the data part. | String |
part_type | The data part storing format. Possible Values: Wide (a file per column) and Compact (a single file for all columns). | String |
parent_name | The name of the source (parent) data part. | String |
parent_uuid | The UUID of the source (parent) data part. | UUID |
parent_part_type | The source (parent) data part storing format. | String |
active | 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. | UInt8 |
marks | 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). | UInt64 |
rows | The number of rows. | UInt64 |
bytes_on_disk | Total size of all the data part files in bytes. | UInt64 |
data_compressed_bytes | Total size of compressed data in the data part. All the auxiliary files (for example, files with marks) are not included. | UInt64 |
data_uncompressed_bytes | Total size of uncompressed data in the data part. All the auxiliary files (for example, files with marks) are not included. | UInt64 |
marks_bytes | The size of the file with marks. | UInt64 |
parent_marks | The number of marks in the source (parent) part. | UInt64 |
parent_rows | The number of rows in the source (parent) part. | UInt64 |
parent_bytes_on_disk | Total size of all the source (parent) data part files in bytes. | UInt64 |
parent_data_compressed_bytes | Total size of compressed data in the source (parent) data part. | UInt64 |
parent_data_uncompressed_bytes | Total size of uncompressed data in the source (parent) data part. | UInt64 |
parent_marks_bytes | The size of the file with marks in the source (parent) data part. | UInt64 |
modification_time | The time the directory with the data part was modified. This usually corresponds to the time of data part creation. | DateTime |
remove_time | The time when the data part became inactive. | DateTime |
refcount | 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. | UInt32 |
min_date | The minimum value of the date key in the data part. | Date |
max_date | The maximum value of the date key in the data part. | Date |
min_time | The minimum value of the date and time key in the data part. | DateTime |
max_time | The maximum value of the date and time key in the data part. | DateTime |
partition_id | ID of the partition. | String |
min_block_number | The minimum number of data parts that make up the current part after merging. | Int64 |
max_block_number | The maximum number of data parts that make up the current part after merging. | Int64 |
level | Depth of the merge tree. Zero means that the current part was created by insert rather than by merging other parts. | UInt32 |
data_version | Number that is used to determine which mutations should be applied to the data part (mutations with a version higher than data_version). | UInt64 |
primary_key_bytes_in_memory | The amount of memory (in bytes) used by primary key values. | UInt64 |
primary_key_bytes_in_memory_allocated | The amount of memory (in bytes) reserved for primary key values. | UInt64 |
is_frozen | Flag that shows that a partition data backup exists. 1, the backup exists. 0, the backup does not exist. | UInt8 |
database | Name of the database. | String |
table | Name of the table. | String |
engine | Name of the table engine without parameters. | String |
disk_name | Name of a disk that stores the data part. | String |
path | Absolute path to the folder with data part files. | String |
hash_of_all_files | sipHash128 of compressed files. | String |
hash_of_uncompressed_files | sipHash128 of uncompressed files (files with marks, index file etc.). | String |
uncompressed_hash_of_compressed_files | sipHash128 of data in the compressed files as if they were uncompressed. | String |
delete_ttl_info_min | The minimum value of the date and time key for TTL DELETE rule. | DateTime |
delete_ttl_info_max | The maximum value of the date and time key for TTL DELETE rule. | DateTime |
move_ttl_info.expression | Array of expressions. Each expression defines a TTL MOVE rule. | Array(String) |
move_ttl_info.min | Array of date and time values. Each element describes the minimum key value for a TTL MOVE rule. | Array(DateTime) |
move_ttl_info.max | Array of date and time values. Each element describes the maximum key value for a TTL MOVE rule. | Array(DateTime) |
default_compression_codec | The name of the codec used to compress this data part (in case when there is no explicit codec for columns). | String |
recompression_ttl_info.expression | The TTL expression. | Array(String) |
recompression_ttl_info.min | The minimum value of the calculated TTL expression within this part. Used to understand whether we have at least one row with expired TTL. | Array(DateTime) |
recompression_ttl_info.max | The maximum value of the calculated TTL expression within this part. Used to understand whether we have all rows with expired TTL. | Array(DateTime) |
group_by_ttl_info.expression | The TTL expression. | Array(String) |
group_by_ttl_info.min | The minimum value of the calculated TTL expression within this part. Used to understand whether we have at least one row with expired TTL. | Array(DateTime) |
group_by_ttl_info.max | The maximum value of the calculated TTL expression within this part. Used to understand whether we have all rows with expired TTL. | Array(DateTime) |
rows_where_ttl_info.expression | The TTL expression. | Array(String) |
rows_where_ttl_info.min | The minimum value of the calculated TTL expression within this part. Used to understand whether we have at least one row with expired TTL. | Array(DateTime) |
rows_where_ttl_info.max | The maximum value of the calculated TTL expression within this part. Used to understand whether we have all rows with expired TTL. | Array(DateTime) |
is_broken | Whether projection part is broken | UInt8 |
exception_code | Exception message explaining broken state of the projection part | Int32 |
exception | Exception code explaining broken state of the projection part | String |
bytes | Alias for bytes_on_disk | UInt64 |
marks_size | Alias for marks_bytes | UInt64 |
part_name | Alias for name | String |
