rzhang10 commented on code in PR #4301: URL: https://github.com/apache/iceberg/pull/4301#discussion_r842025467
########## format/spec.md: ########## @@ -193,6 +193,17 @@ Notes: For details on how to serialize a schema to JSON, see Appendix C. +#### Default value + +Default value can be assigned to a column when the column is added to an Iceberg table as part of the schema evolution. They are tracked at the level of a nested field inside a struct, thus it can be used for both top-level columns and nested columns. Iceberg tracks two default values internally: `initial-default` and `write-default`. The `initial-default` is used to read rows belonging to files that lack the column (i.e. the files were written before the column is added); the `write-default` value will be used for the automatically populating the column if user later inserts new rows without specifying the column. Review Comment: @rdblue Updated the spec according to the above discussions, could you take a look again? -- 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]
