findinpath commented on code in PR #11041: URL: https://github.com/apache/iceberg/pull/11041#discussion_r4539149937
########## format/view-spec.md: ########## @@ -160,7 +180,94 @@ Each entry in `version-log` is a struct with the following fields: | _required_ | `timestamp-ms` | Timestamp when the view's `current-version-id` was updated (ms from epoch) | | _required_ | `version-id` | ID that `current-version-id` was set to | -## Appendix A: An Example +#### Storage Table Identifier + +The table identifier for the storage table that stores the precomputed results. + +| Requirement | Field name | Description | +|-------------|----------------|-------------| +| _required_ | `namespace` | A list of strings for namespace levels | +| _required_ | `name` | A string specifying the name of the table | + +### Storage table metadata + +This section describes additional metadata for the storage table that supplements the regular table metadata and is required for materialized views. +The `refresh-state` property is set on the [snapshot summary](https://iceberg.apache.org/spec/#snapshots) property of a storage table snapshot to provide information about the state of the precomputed data. + +| Requirement | Field name | Description | +|-------------|-----------------|-------------| +| _optional_ | `refresh-state` | A [refresh state](#refresh-state) record stored as a JSON-encoded string | + +Snapshots written by a refresh operation must set `refresh-state`. + +#### Refresh state + +Query engines maintain the precomputed data in the storage table by executing the materialized view’s query. During a refresh, the engine records the state of the view’s dependencies in the refresh state. Which dependencies are available depends on how source materialized views are treated, and the writer chooses which of them to record: all, a subset, or none. See [Appendix B](#appendix-b-example-freshness-criteria-and-recorded-dependencies) for examples. Each recorded dependency appears in `source-states` as a table entry or a view entry. A source materialized view may be recorded as a view entry for its definition and, optionally, a table entry for its storage table. + +The refresh state has the following fields: + +| Requirement | Field name | Description | +|-------------|------------------------------|-------------| +| _required_ | `refresh-start-timestamp-ms` | A timestamp of when the refresh operation was started | +| _required_ | `view-version-id` | The `version-id` of the materialized view when the refresh operation was performed | +| _required_ | `source-states` | A list of [source state](#source-state) records capturing the dependencies the writer chose to record; may be empty | + +When writing the refresh state, writers may leave source-states empty (e.g., when sources are non-Iceberg or freshness is determined by a mechanism outside this spec). Review Comment: > when sources are non-Iceberg when sources are non-Iceberg tables -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
