WL#9436: ST_SwapXY

When introducing geography support, data may be in latitude-longitude or longitude-latitude format. MySQL will interpret stored geometries as if they are in longitude-latitude format, i.e., the first coordinate is longitude, the second is latitude.

Users may have existing data that assumes the wrong axis order for geographic data. This WL adds a function ST_SwapXY that swaps all coordinate pairs in a geometry:

<geometry> = ST_SwapXY(<geometry>)

User Documentation

• http://dev.mysql.com/doc/relnotes/mysql/8.0/en/news-8-0-1.html
• http://dev.mysql.com/doc/refman/8.0/en/gis-format-conversion-functions.html#function_st-swapxy

F-1

If the function argument is NULL, the function MUST return NULL.

F-2

If the function argument is not a well-formed geometry value, the function MUST raise ER_GIS_INVALID_DATA.

F-3

If the function argument is a well-formed geometry value, the function MUST return a geometry of the same type with all X and Y coordinates swapped.

NF-1

The function MUST be non-nullable if the argument is non-nullable.

I-1

No new files.

I-2

Interface SQL02 is extended with one new function:
<geometry> = ST_SwapXY(<geometry>)

I-3

No new commands.

I-4

No new tools.

I-5

No impact on existing functionality.

I-6

No new errors.

I-7

No new warnings.

Add a new item, Item_func_swap_xy, and a Create_func_swap_xy class for a one-argument function.

When evaluating the function, return a geometry where the X and Y coordinates of all coordinate pairs have been swapped.