Transbase® D enables the distributed execution of transactions and SQL queries across multiple Transbase® Databases as well as the combination of offline and online deployments for hybrid applications. Database queries can thus be distributed to a local CD / DVD database and to a central online database.They combine the advantages of online and offline operation and avoid the disadvantages of pure online operation, which results from limited bandwidth, high communication costs and reliability problems.
Transbase® D enables the
- Division of databases in a local and in a central database
- Transfer of records from a serverdatabase to a client database using SQL
- Addition of local data or update via download
- Transfer of data records to a central server database
- Upload of changes and central processing
- Division of logical databases into a pure read-only database and into a read-write database -> Possibility of cross-processing of queries
All databases involved in a distributed query must be based on a Transbase® Database Version 6.1 or higher. All databases must have the same authorization data, ie the same login and the same password.
A distributed query is first processed using the data dictionary of the receiving database. Remote tables or views can be referenced as if they were local: <table_or_view_name>@<dbname>@<hostname>
For such a reference Transbase® establishes a connection to the remote database and first fetches all the data dictionary information relating to this table or view. Then the distributed query will be broken-up in such a way that a maximal query can be processed there, especially taking into account the local restrictions or remote sort operations.
The part of a query allocated to the remote database is transmitted to it in the form of an operator tree, which can there be processed without further translation. The execution of the distributed query is managed by the receiving database. As necessary the local transaction will be shared automatically with the remote database. If more than one write database is involved, a 2 phase commit is automatically carried out.
The connection to a distributed database is maintained at least until the end of the transaction. If Transbase® is configured for parallel query processing, the remote queries will be processed asynchronously, so that local and remote processing can be performed in parallel.