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pull/7267/head
gindibay 2023-10-31 16:11:12 +03:00
parent cd7e8e13a2
commit e5b66122af
1 changed files with 9 additions and 3 deletions
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src/backend/distributed/README.md
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@ -1772,11 +1772,17 @@ Each field in the struct is documented in the comments within the `DistributeObj
- **Returning tasks for `preprocess` and `postprocess`**: Ensure that either `preprocess` or `postprocess` returns a list of "DDLJob"s. If both functions return non-empty lists, then you would get an assertion failure. - **Returning tasks for `preprocess` and `postprocess`**: Ensure that either `preprocess` or `postprocess` returns a list of "DDLJob"s. If both functions return non-empty lists, then you would get an assertion failure.
- **Generic `preprocess` and `postprocess` methods**: ``PreprocessAlterDistributedObjectStmt`` and ``PostprocessAlterDistributedObjectStmt`` are generic post and pre methods that are used for some statements. Both of them are being used for distributed object operations. - **Generic `preprocess` and `postprocess` methods**: The generic methods, `PreprocessAlterDistributedObjectStmt` and `PostprocessAlterDistributedObjectStmt`, serve as generic pre and post methods utilized for various statements. Both of these methods find application in distributed object operations.
- PreprocessAlterDistributedObjectStmt perform below operations perform qualify operation, deparse the statement and generate a task list. PostprocessAlterDistributedObjectStmt - calls ``EnsureAllObjectDependenciesExistOnAllNodes`` to propagate missing dependencies both on coordinator and worker. - The `PreprocessAlterDistributedObjectStmt` method carries out the following operations:
- Performs a qualification operation.
- Deparses the statement and generates a task list.
- As for the `PostprocessAlterDistributedObjectStmt` method, it:
- Invokes the `EnsureAllObjectDependenciesExistOnAllNodes` function to propagate missing dependencies, both on the coordinator and the worker.
- Before defining new `preprocess` or `postprocess` methods, it is advisable to assess whether the generic methods can be employed in your specific case.
- Before defining a new `preprocess` or `postprocess` method, check if the generic methods can be used in your case.
- **`deparse`**: When propagating the command to worker nodes, make sure to define `deparse`. This is necessary because it generates a query string for each worker node. - **`deparse`**: When propagating the command to worker nodes, make sure to define `deparse`. This is necessary because it generates a query string for each worker node.