paleolimbot commented on code in PR #10981: URL: https://github.com/apache/iceberg/pull/10981#discussion_r1907689826
########## format/spec.md: ########## @@ -1633,3 +1652,27 @@ might indicate different snapshot IDs for a specific timestamp. The discrepancie When processing point in time queries implementations should use "snapshot-log" metadata to lookup the table state at the given point in time. This ensures time-travel queries reflect the state of the table at the provided timestamp. For example a SQL query like `SELECT * FROM prod.db.table TIMESTAMP AS OF '1986-10-26 01:21:00Z';` would find the snapshot of the Iceberg table just prior to '1986-10-26 01:21:00 UTC' in the snapshot logs and use the metadata from that snapshot to perform the scan of the table. If no snapshot exists prior to the timestamp given or "snapshot-log" is not populated (it is an optional field), then systems should raise an informative error message about the missing metadata. +## Appendix G: Geospatial Notes + +The Geometry and Geography class hierarchy and its WKT and WKB serializations (ISO supporting XY, XYZ, XYM, XYZM) are defined by [OpenGIS Implementation Specification for Geographic information – Simple feature access – Part 1: Common architecture](https://portal.ogc.org/files/?artifact_id=25355), from [OGC (Open Geospatial Consortium)](https://www.ogc.org/standard/sfa/). + +The version of the OGC standard first used here is 1.2.1, but future versions may also used if the WKB representation remains wire-compatible. + +Coordinate axis order is always (x, y) where x is easting or longitude, and y is northing or latitude. This ordering explicitly overrides the axis order specified in the CRS. Review Comment: Just a note that it's fine either way for me because `srid` is opaque (i.e., the engine is free to map `4326` however it wants, even though `EPSG:4326` is defined reversed to how it is represented in almost all databases/file formats), and because `projjson` is capable of representing flipping the axes based on their name if needed. I do think it will cause considerable confusion/a lot of unexpectedly sideways maps if omitted; however, but it is not strictly required). -- 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
