ducklake_data_file

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Documentation / Specification / Tables

ducklake_data_file

Data files contain the actual row data.

Column name	Column type
`data_file_id`	`BIGINT`	Primary key
`table_id`	`BIGINT`
`begin_snapshot`	`BIGINT`
`end_snapshot`	`BIGINT`
`file_order`	`BIGINT`
`path`	`VARCHAR`
`path_is_relative`	`BOOLEAN`
`file_format`	`VARCHAR`
`record_count`	`BIGINT`
`file_size_bytes`	`BIGINT`
`footer_size`	`BIGINT`
`row_id_start`	`BIGINT`
`partition_id`	`BIGINT`
`encryption_key`	`VARCHAR`
`mapping_id`	`BIGINT`
`partial_max`	`BIGINT`

data_file_id is the numeric identifier of the file. It is a primary key. data_file_id is incremented from next_file_id in the ducklake_snapshot table.
table_id refers to a table_id from the ducklake_table table.
begin_snapshot refers to a snapshot_id from the ducklake_snapshot table. The file is part of the table starting with this snapshot id.
end_snapshot refers to a snapshot_id from the ducklake_snapshot table. The file is part of the table up to but not including this snapshot id. If end_snapshot is NULL, the file is currently part of the table.
file_order is a number that defines the vertical position of the file in the table. It needs to be unique within a snapshot but does not have to be contiguous (gaps are ok).
path is the file path of the data file, e.g., my_file.parquet for a relative path.
path_is_relative whether the path is relative to the path of the table (true) or an absolute path (false).
file_format is the storage format of the file. Currently, only parquet is allowed.
record_count is the number of records (row) in the file.
file_size_bytes is the size of the file in bytes.
footer_size is the size of the file metadata footer, in the case of Parquet the Thrift data. This is an optimization that allows for faster reading of the file.
row_id_start is the first logical row id in the file. (Every row has a unique row id that is maintained.)
partition_id refers to a partition_id from the ducklake_partition_info table.
encryption_key contains the encryption for the file if encryption is enabled.
mapping_id refers to a mapping_id from the ducklake_column_mapping table.
partial_max is the maximum snapshot id stored in a partial data file. When multiple snapshots are merged into a single file, per-row snapshot ownership is tracked via the _ducklake_internal_snapshot_id column embedded in the Parquet file. partial_max records the highest snapshot id present in that merged file, so reads and time travel can determine whether snapshot filtering is necessary. It is NULL for files that are not shared across snapshots.