Join and transform polygons
Real spatial work when the polygons start out in the table rather than in R
Not yet written. The structure below is settled; the prose is not.
The spatial functions are on both sides of the line
23 of 23 probed ST_ functions work server-side, so needing a spatial operation is not by itself a reason to bring data back.
The reader’s likely prior is that spatial work means sf, and therefore means R, and therefore means collecting everything first. The page’s job is to break that chain in its first paragraph. Give the count and let it carry the argument.
Set the CRS yourself
Polygons are stored as WKB in a BINARY column with no embedded SRID. st_srid returns 0, and the number has to come from you.
This is the fact most likely to produce a silently wrong answer on this page, because a missing CRS does not error: it produces areas in the wrong units or joins that match nothing. State that consequence, not just the mechanism.
Transforming once, server-side, instead of per iteration
EPSG:4326 to EPSG:27700, worked.
Aggregating server-side when only a scalar needs to cross
The best case on the site: the work happens where the data is and a single number comes back. Worth showing because it is the shape she should be looking for in her own analysis.
The full sf pipeline below the line, when that is what you want
Needed as a genuine option rather than a fallback, and the page should not apologise for it. If the data fits and the pipeline is already written, bringing it back is the right call. The connection caveat applies: geometry cannot travel over the ODBC path, so this route needs brickster::DatabricksSQL(). See Connect your R session to the data.
Points work the same way
Next
Gridded data does not work like this. And if you want to confirm the server-side answer matches R’s, see Check that you get the same answer wherever it ran.
This page rests on: 23 of 23 probed native ST_ functions work on the SQL warehouse; st_transform works server-side between EPSG:4326 and EPSG:27700; geometry is stored as WKB with no embedded SRID; polygon area aggregates server-side with only a scalar crossing.