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The following page has been changed by KevinWilliams: http://wiki.apache.org/ws/Tuscany/TuscanyJava/DAS_Java_Overview/RDBDAS_Java_User_Guide/Write_Operation_Ordering ------------------------------------------------------------------------------ Relational databases often use [http://en.wikipedia.org/wiki/Referential_integrity Referential Integrity (RI)] constraints to maintain database consistency. When RI is enabled, database operations must be performed in a specific order that prevents invalid references. If this order is not adhered to then the database will throw an exception rather than let the write succeed. - When an application makes modifications to a data graph and then asks the RDB DAS to "apply changes", the DAS will create a "batch" of database writes that must be sorted and the executed in the correct order to avoid RI Constraint exceptions. A simple example will help here. Assume a database with two tables CUSTOMER and ORDER. Also assume that the ORDER table has a [http://en.wikipedia.org/wiki/Foreign_key foreign key] reference to the CUSTOMER table. Now assume that the application has made modifications to a data graph that was retrieved by the DAS using a SELECT statement like the following: + When an application makes modifications to a data graph and then asks the RDB DAS to "apply changes", the DAS will create a "batch" of database writes that must be sorted and then executed in the correct order to avoid RI Constraint exceptions. A simple example will help here. Assume a database with two tables CUSTOMER and ORDER. Also assume that the ORDER table has a [http://en.wikipedia.org/wiki/Foreign_key foreign key] reference to the CUSTOMER table. Now assume that the application has made modifications to a data graph that was retrieved by the DAS using a SELECT statement like the following: {{{ SELECT * FROM CUSTOMER LEFT JOIN ORDER ON CUSTOMER.ID = ORDER.CUSTOMER_ID WHERE CUSTOMER.NAME = ? --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
