Currently, metadata files are pretty-printed, with lots of new-lines and whitespace indentations. This is the relevant line of code, which uses the Jackson default pretty printer: https://github.com/apache/iceberg/blob/abb47830e7df7dc2ae93c74b0ad97f06cdd37aad/core/src/main/java/org/apache/iceberg/TableMetadataParser.java#L131
If we could write metadata files without redundant whitespace, then it would save some storage space, and network overhead. This will have have most impact for tables with large metadata files. For example, I have seen a metadata files which was 53.6MB. After removing whitespace, this was reduced to 41.4MB. I have read other issues in github which mention gigabyte-scale metadata files. I cannot think of any downside of this suggested change. Metadata files are mainly read by machines not humans. And if a human does want to inspect a metadata file, then it is fairly easy to prettify a JSON file when needed. I opened this as an issue in github, and then took advice to move the discussion to this dev list. See https://github.com/apache/iceberg/issues/12281 I would appreciate hearing your thoughts. Thanks, Ian
