system.projection_parts_columns
This table contains information about columns in 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. | 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 | UInt8 |
marks | The number of marks. | 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 for the Date column if that is included in the partition key. | Date |
max_date | The maximum value for the Date column if that is included in the partition key. | Date |
min_time | The minimum value for the DateTime column if that is included in the partition key. | DateTime |
max_time | The maximum value for the DateTime column if that is included in the partition key. | 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 |
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 |
column | Name of the column. | String |
type | Column type. | String |
column_position | Ordinal position of a column in a table starting with 1. | UInt64 |
default_kind | Expression type (DEFAULT, MATERIALIZED, ALIAS) for the default value, or an empty string if it is not defined. | String |
default_expression | Expression for the default value, or an empty string if it is not defined. | String |
column_bytes_on_disk | Total size of the column in bytes. | UInt64 |
column_data_compressed_bytes | Total size of compressed data in the column, in bytes. | UInt64 |
column_data_uncompressed_bytes | Total size of the decompressed data in the column, in bytes. | UInt64 |
column_marks_bytes | The size of the column with marks, in bytes. | UInt64 |
column_modification_time | The last time the column was modified. | Nullable(DateTime) |
bytes | Alias for bytes_on_disk | UInt64 |
marks_size | Alias for marks_bytes | UInt64 |
part_name | Alias for name | String |
