Hints

Using a Hint String, the developer can specify a hard-coded string that can be added to the Select statement as is, without being checked. The syntax of a Hint is:

/*+ Oracle Hint */.

It is recommended that you use the Optimizer Hints in special cases only. A full list of the Optimizer Hints that can be sent to Oracle can be found in the Oracle documentation.

Physical Locking

A physical lock is a method that ensures that no one else can modify a record that is currently locked. Specifically, from the moment a user locks the record until that user releases the record, the record cannot be modified by another user. The physical lock is implemented as follows: When Magic xpa locks a record according to its locking strategy, Magic xpa issues a Select statement with a FOR UPDATE clause.

The FOR UPDATE clause prevents other applications from making changes to the record until the end of the transaction.

Table Locking

Table locking is available only within a Magic xpa transaction. Magic xpa will ignore the request if it is issued outside of a transaction. Therefore, Share None refers to an Exclusive table lock and Share Read refers to a Share table lock.

Unique Identifier

Magic xpa must have a unique row identifier for each table that it opens. Whenever possible, Magic xpa will use Oracle’s ROWID as the unique identifier. If the data view is built from fields from more than one Oracle database table, there will be no Oracle ROWID, and a unique index must be entered. This may be a virtual index.

Views

A View must have a virtual unique index defined. Insert, Update, and Delete operations are allowed on Views, but only if that View has a ROWID. A View that is defined on more than one table does not have a ROWID. Therefore, the Position property on the SQL tab in the Data Source Properties dialog should be Unique Index, and not Default or ROWID.

The Magic xpa Single User Edition does not support the Oracle database.