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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/Partial_Update ------------------------------------------------------------------------------ = Partial Update = - The RDB DAS uses the SDO Change Summary to generate a set of database write operations. Rather than generated a statment to update all columns in a table that maps to a SDO DataObject Type, the DAS generates statements that update ony those columns that map to a modified DataObject property. For example, consider a Customer DataObject that has had the LastName property changed. The '''partial update''' statement generated by the DAS will look somthing like this: + The RDB DAS uses the SDO Change Summary to generate a set of database write operations. Rather than generated a statement to update all columns in a table that maps to a SDO DataObject Type, the DAS generates statements that update ony those columns that map to a modified DataObject property. For example, consider a Customer DataObject that has had the LastName property changed. The '''partial update''' statement generated by the DAS will look something like this: {{{ UPDATE CUSTOMER SET LASTNAME = ? WHERE ID = ? }}} @@ -11, +11 @@ UPDATE CUSTOMER SET FIRSTNAME = ?, SET LASTNAME = ?, SET ADDRESS = ?, SET PHONE = ?, SET AGE = ?, SET SHOESIZE = ? WHERE ID = ? }}} - There are a couple of very good reasons for using a partial update approach. For one, a performance boost can be reaized by applications writing to very wide tables. For example, this author has seen customer tables with over 100 columns. I can be a waste of resources to update 100 columns when only one was modified. Another reason is that some databases also employ [http://en.wikipedia.org/wiki/Database_trigger triggers] on specific columns in a table. Prtial updates are necessary when column triggers are employed to avoid tripping the trigger on every row update rather than only on updates to the specific column. + There are a couple of very good reasons for using a partial update approach. For one, a performance boost can be realized by applications writing to very wide tables. For example, this author has seen customer tables with over 100 columns. I can be a waste of resources to update 100 columns when only one was modified. Another reason is that some databases also employ [http://en.wikipedia.org/wiki/Database_trigger triggers] on specific columns in a table. Partial updates are necessary when column triggers are employed to avoid tripping the trigger on every row update rather than only on updates to the specific column. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
