I just thought I’d take a few moments clarify the upcoming coordinate order swap for the geography type. Here’s a quick FAQ on the issue:
- What exactly is the change?
We are swapping the coordinate order for well-known text (WKT) and well-known binary (WKB) formats from latitude-longitude to longitude-latitude. E.g., a point in the Seattle area might be represented in WKT as “POINT(44 -122)” in the current ordering; in the new order it will be “POINT(-122 44)”.
- Why are we making this change?
Because of customer feedback. While common practice almost universally uses latitude-longitude ordering, the de facto standard for WKT and WKB is to use a longitude-latitude order. Making this change will make it much easier for customers to load WKT and WKB data into the geography type.
- What about GML?
The standard paractice for GML is to use latitude-longitude ordering, and so no change will be made for GML.
- Is the on-disk format changing?
Nope. Ths is just a matter of changing our routines that import and export data. Nothing beyond those routines will change.
- What about geometry?
There is no change to the geometry type. Geometry deals with objects on the plane, and is pretty agnostic about the coordinate order outsidfe of the STX and STY properties.
- When is the swap happening?
It is not the current Februrary CTP, but the team is working on it now. Expect to see it in our next public release.
If there are more questions, I’ll be happy to answer them here.
Minor Update: I originally got the WKT examples at the top wrong, placing commas between coordinates. The examples have been updated to their correct, comma-free state. (Thanks, Steven!)