something about,
embedded documents
atomicity and transaction
$isolated operator
two-phase commit
only transaction-like for multiple document
multi-document transaction, rollback-like functionality, not really an all or nothing transaction
- atomicity, rollback previous state
- consistency, consistent state recovery
intermediate data presentation
concurrency control : two approach, unique index, update if current
Update if current pattern
an approach to currency control for multiple clients operate the same data
version pattern
variant : version pattern , similar to Update if current pattern
to add an version field to document schema, application/client need increment the version field upon each update operation to a specific document.
version field can be set 1 as default value for a document creation / insert operation.
it need ensure client application query data including the version field.
version can be implemented by “auto-incrementing sequence” field
SQL2Mongo
SQL2Mongo : tool to migrate all schema and data from MSSQL to mongodb,