Add new records to a table

x upsert y    upsert[x;y]

Where

• x is a table, or the name of a table as a symbol atom, or the name of a splayed table as a directory handle
• y is one or more records with types matching x, or a table with conforming columns

If x is the name of a table, it is updated in place. Otherwise the updated table is returned.

If x is the name of a table as a symbol atom (or the name of a splayed table as a directory handle) that does not exits in the file system, it is written.