The 26-year-old will move to Spotland Stadium when his contract with Plymouth expires on July 1.
"I'm really pleased to be here and I cannot wait to get started," Alessandra told Rochdale's official website. "I have been a big admirer of the manager Keith Hill for a while."
Alessandra has scored 25 goals in 102 appearances for Plymouth since joining the club from Morecambe in 2013.
Restore Data
| Team | P | W | D | L | F | A | GD | PTS | |
| 1 | York City | 17 | 11 | 5 | 1 | 33 | 12 | 21 | 38 |
| 2 | Forest Green RoversForest Green | 17 | 11 | 4 | 2 | 33 | 14 | 19 | 37 |
| 3 | Barnet | 17 | 11 | 1 | 5 | 34 | 20 | 14 | 34 |
| 4 | Gateshead | 17 | 10 | 3 | 4 | 28 | 22 | 6 | 33 |
| 5 | Oldham AthleticOldham | 17 | 8 | 7 | 2 | 25 | 17 | 8 | 31 |
| 6 | Rochdale | 17 | 9 | 3 | 5 | 27 | 16 | 11 | 30 |
| 7 | Yeovil TownYeovil | 17 | 8 | 4 | 5 | 21 | 15 | 6 | 28 |
| 8 | Halifax TownHalifax | 17 | 7 | 5 | 5 | 19 | 16 | 3 | 26 |
| 9 | Solihull MoorsSolihull | 17 | 7 | 4 | 6 | 26 | 28 | -2 | 25 |
| 10 | AltrinchamAltrincham | 17 | 6 | 6 | 5 | 26 | 23 | 3 | 24 |
| 11 | Eastleigh | 17 | 6 | 5 | 6 | 25 | 25 | 0 | 23 |
| 12 | Dagenham & RedbridgeDag & Red | 17 | 5 | 7 | 5 | 27 | 18 | 9 | 22 |
| 13 | Sutton UnitedSutton | 17 | 6 | 4 | 7 | 25 | 26 | -1 | 22 |
| 14 | Tamworth | 17 | 6 | 4 | 7 | 20 | 28 | -8 | 22 |
| 15 | Southend UnitedSouthend | 17 | 5 | 6 | 6 | 20 | 20 | 0 | 21 |
| 16 | Hartlepool UnitedHartlepool | 17 | 5 | 6 | 6 | 18 | 21 | -3 | 21 |
| 17 | Aldershot TownAldershot | 17 | 4 | 6 | 7 | 21 | 27 | -6 | 18 |
| 18 | Fylde | 17 | 5 | 3 | 9 | 23 | 36 | -13 | 18 |
| 19 | Woking | 17 | 4 | 5 | 8 | 18 | 24 | -6 | 17 |
| 20 | Braintree TownBraintree | 17 | 4 | 4 | 9 | 13 | 20 | -7 | 16 |
| 21 | Maidenhead UnitedMaidenhead | 17 | 4 | 4 | 9 | 21 | 30 | -9 | 16 |
| 22 | WealdstoneWealdstone | 17 | 3 | 6 | 8 | 16 | 25 | -9 | 15 |
| 23 | Boston UnitedBoston | 17 | 2 | 5 | 10 | 16 | 30 | -14 | 11 |
| 24 | Ebbsfleet | 17 | 1 | 5 | 11 | 15 | 37 | -22 | 8 |
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