I’m trying to calculate a good chunk size for a simple array holding geospatial data. Forgive me if I’m overlooking the obvious but after reading the respective section in the manual I’m not entirely sure how to do it…
To quote the manual:
The first two sentences are clear, it’s the next two (in bold) that I don’t get. The information I read is “The chunk size is the chunk size”, possibly because I misunderstand the terms number of cells and/or chunk size. Then, a straightforward calculation is mentioned but not given or explained - could you give an example for the not-so-gifted like me?
The schema for my array looks like this
SpatialGridNode <lat:float,lon:float,cellid:int64 NULL DEFAULT null,land_flag:bool> [gpi]
In essence, you have geographic coordinates (lat/lon) and a flag to indicate whether these are on land or ocean (land_flag). The coordinates are grouped into regions called cells, hence the cellid.
So how do I calculate a good chunk size value for this array?
Oh, and is there a list of byte sizes for the data types? I checked this manual page but found nothing.