RMySQL dbWriteTable with field.types
After playing with things, I realized what the problem is: field.types must be a NAMED list vector, not simply a list; additionally the row names must not be included otherwise we need three field types. For the above example, the following works fine:
dbWriteTable(con, name="table_name", value=df, field.types = c(dte="date", val="double(20,10)"), row.names=FALSE)