| # FAQ |
| |
| **Q1: Is Saga executed synchronously or asynchronously？Will Saga not be finished until all sub-transaction finished?** |
| |
| Currently Saga is executed synchronously. Asynchronous mode will be implemented in future. |
| |
| |
| **Q2: How are sub-transactions executed by Saga, in parallel or in sequence?** |
| |
| How Saga pack executes sub-transaction depends on your code. If you call `@Compensable` method in parallel, then Saga Alpha will process in parallel. |
| |
| |
| **Q3: Any requirements on `@Compensable` method and compenstation method？** |
| |
| Here are the requirements： |
| |
| 1. Both methods should be idempotent. |
| 1. Both methods have exactly same parameter list. |
| 1. Both methods are in same class. |
| 1. Parameter should be serializable. |
| 1. They should be commutative. For example, if given same parameters, the result should be same regardless the order of execution. |
| |
| |
| **Q4: Does Saga guarantee ACID?** |
| |
| Saga guarantees Atomicity, Consistency, Durability, but not guarantee Isolation。 |
| |
| |
| **Q5: Can Saga be nested?** |
| |
| Yes, Saga can be nested. |
| |
| |
| **Q6: How to scale Saga Alpha horizontally?** |
| |
| Saga Alpha is stateless, all data is persisted in database, so it supports horizontal scale. |
| |
| |
| **Q7: Will Saga continue if some services crashed in execution?** |
| |
| Saga Alpha will try to continue Saga execution after service restart. |
| |
| |
| **Q8: How to use MySQL as alpha's backend database?** |
| |
| Check this [doc](docs/faq/en/how_to_use_mysql_as_alpha_backend_database.md) |
| |
| **Q9: How to resolve the issue that Omega cannot run the command from Alpha? |
| |
| Check this [doc](docs/faq/en/omega-cannot-run-command-from-alpha.md) |
