The Venetian state was always an ad hoc construct, and institutions came and went at the convenience of the ruling elite.
“Doge” from the L’Archivio di Stato di Venezia: indice generale, storico, descrittivo ed analitico (1937) by Andrea da Mosto
The complete list of the 120 Doges of Venice from Paoluccio Anafesto in 697 to Ludovico Manin in 1797