dbGetQuery(conn, "SELECT a FROM table") where a is a BLOB results in message about truncated field (and no data). Equivalent operation using RSQLite results in correct raw vector being returned, which can then be read as binary. My workaround with RMySQL is to request the server to cast the field to a HEX string, which you can then parse into a RAW and then read as binary. It would be great to have the same functionality for BLOBs in RMySQL as in SQLite.