stevenzwu commented on code in PR #11041: URL: https://github.com/apache/iceberg/pull/11041#discussion_r2288776869
########## format/view-spec.md: ########## @@ -42,12 +42,28 @@ An atomic swap of one view metadata file for another provides the basis for maki Writers create view metadata files optimistically, assuming that the current metadata location will not be changed before the writer's commit. Once a writer has created an update, it commits by swapping the view's metadata file pointer from the base location to the new location. +### Materialized Views + +Materialized views are a type of view with precomputed results from the view query stored as a table. +When queried, engines may return the precomputed data for the materialized views, shifting the cost of query execution to the precomputation step. + +Iceberg materialized views are implemented as a combination of an Iceberg view and an underlying Iceberg table, the "storage-table", which stores the precomputed data. +Materialized View metadata is a superset of View metadata with an additional pointer to the storage table which contains additional refresh metadata. Review Comment: Maybe it is my interpretation problem. `which` can be interpreted as the `pointer` or the `storage table`. I know it meant the later. The following paraphrase can avoid the potential misinterpretation. ``` Materialized View metadata is a superset of View metadata with an additional pointer to the storage table. The storage table is an Iceberg table with additional materialized view refresh state metadata. ``` I also think the sentence below may not be needed here. It is not clear from the description. maybe better just leave it out and let the later refresh-state section coveres it. ``` Refresh metadata contains information about the "source tables" and/or "source views", tables referenced in the query definition of the materialized view. ``` ########## format/view-spec.md: ########## @@ -42,12 +42,28 @@ An atomic swap of one view metadata file for another provides the basis for maki Writers create view metadata files optimistically, assuming that the current metadata location will not be changed before the writer's commit. Once a writer has created an update, it commits by swapping the view's metadata file pointer from the base location to the new location. +### Materialized Views + +Materialized views are a type of view with precomputed results from the view query stored as a table. +When queried, engines may return the precomputed data for the materialized views, shifting the cost of query execution to the precomputation step. + +Iceberg materialized views are implemented as a combination of an Iceberg view and an underlying Iceberg table, the "storage-table", which stores the precomputed data. +Materialized View metadata is a superset of View metadata with an additional pointer to the storage table which contains additional refresh metadata. +Refresh metadata contains information about the "source tables" and/or "source views", tables referenced in the query definition of the materialized view. +During read time, a materialized view (storage table) can be interpreted as "fresh", "stale" or "invalid", depending on the following the following situations: Review Comment: duplicate `the following` in this line -- 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: issues-unsubscr...@iceberg.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: issues-unsubscr...@iceberg.apache.org For additional commands, e-mail: issues-h...@iceberg.apache.org
