A snapshot is the state of a table at some time.
Each snapshot lists all of the data files that make up the table’s contents at the time of the snapshot. Data files are stored across multiple manifest files, and the manifests for a snapshot are listed in a single manifest list file.
A manifest list is a metadata file that lists the manifests that make up a table snapshot.
Each manifest file in the manifest list is stored with information about its contents, like partition value ranges, used to speed up metadata operations.
A manifest file is a metadata file that lists a subset of data files that make up a snapshot.
A partition spec is a description of how to partition data in a table.
A spec consists of a list of source columns and transforms. A transform produces a partition value from a source value. For example,
date(ts) produces the date associated with a timestamp column named
A partition tuple is a tuple or struct of partition data stored with each data file.
All values in a partition tuple are the same for all rows stored in a data file. Partition tuples are produced by transforming values from row data using a partition spec.
Iceberg stores partition values unmodified, unlike Hive tables that convert values to and from strings in file system paths and keys.
Snapshot log (history table)¶
The snapshot log is a metadata log of how the table’s current snapshot has changed over time.
The log is a list of timestamp and ID pairs: when the current snapshot changed and the snapshot ID the current snapshot was changed to.
The snapshot log is stored in table metadata as