dplyr 1.0.9

• New rows_append() which works like rows_insert() but ignores keys and
  allows you to insert arbitrary rows with a guarantee that the type of x
  won't change (#6249, thanks to @krlmlr for the implementation and @mgirlich
  for the idea).

• The rows_*() functions no longer require that the key values in x uniquely
  identify each row. Additionally, rows_insert() and rows_delete() no
  longer require that the key values in y uniquely identify each row. Relaxing
  this restriction should make these functions more practically useful for
  data frames, and alternative backends can enforce this in other ways as needed
  (i.e. through primary keys) (#5553).

• rows_insert() gained a new conflict argument allowing you greater control
  over rows in y with keys that conflict with keys in x. A conflict arises
  if a key in y already exists in x. By default, a conflict results in an
  error, but you can now also "ignore" these y rows. This is very similar to
  the ON CONFLICT DO NOTHING command from SQL (#5588, with helpful additions
  from @mgirlich and @krlmlr).

• rows_update(), rows_patch(), and rows_delete() gained a new unmatched
  argument allowing you greater control over rows in y with keys that are
  unmatched by the keys in x. By default, an unmatched key results in an
  error, but you can now also "ignore" these y rows (#5984, #5699).

• rows_delete() no longer requires that the columns of y be a strict subset
  of x. Only the columns specified through by will be utilized from y,
  all others will be dropped with a message.

• The rows_*() functions now always retain the column types of x. This
  behavior was documented, but previously wasn't being applied correctly
  (#6240).

• The rows_*() functions now fail elegantly if y is a zero column data frame
  and by isn't specified (#6179).