[BUG] Writing with MPI After Spatial Query

[AstroPatty]

Describe the bug
If different spatial queries are done on different ranks, only one rank's region information is written to the output.

To Reproduce

• Perform a spatial query with MPI, where each rank receives a different query region
• Write the dataset to a file
• Read the file and try to do a follow-up query

[AstroPatty]

This issue will be fixed with the updated MPI semantics that will be required to implement #115