Convert Data Source (Magic xpa 4.x)
There are two cases in which a Magic xpa data source can change:
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Due to a direct change of the column properties. In this case, Magic xpa automatically launches the conversion screen.
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Due to a change in a model, which is used in the Data Source columns, In this case, the conversion screen is not launched automatically. The user can go to the specific (or all) table and select Convert data source from the Options menu.
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If you change an index definition from non-unique to unique, the conversion process deletes all the rows that meet the duplicate index condition.
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Magic xpa maintains the structure of the DBMS table as it existed before the changes, along with the new structure, until the DBMS table row is exited or until the Data repository is exited. If you cancel the conversion process, an inconsistency between the physical and logical structures of the DBMS table may remain. In this case, Magic xpa will not be able to perform an automatic conversion at a later stage and may report an error the next time it accesses the DBMS table.
The conversion process consists of the following stages:
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Magic xpa opens the Confirm Convert Operation dialog box. Click Yes to convert the DBMS table automatically. If you click No, no conversion will take place, in which case you may have to redo the modifications manually.
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If you confirm the convert operation, and depending on the database used, Magic xpa opens the Confirm Backup Operation dialog box. If you want to preserve a copy of the original DBMS table, as it was before it was modified, click Yes. The process creates a BCK file in the current database.
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If you confirm the convert operation, Magic xpa displays the Convert dialog box. In this dialog box, you can request that Magic xpa rearrange the DBMS table according to one of its previously defined indexes. Index 0 arranges the rows in their physical sequence. If you want to arrange the DBMS table according to an index, either type the index's identifier number (from the Index repository), or zoom to the Index list to select an index. [Note: The Index list will include only those indexes which existed before your current editing session; newly-defined indexes are not available.] It is advisable to rearrange a DBMS table according to the index that is most frequently used, to enhance performance when scanning the DBMS table or in any I/O operation with the selected index.
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After you click Yes in the Convert dialog box, Magic xpa carries out the conversion. A Convert dialog box appears and displays the number of rows converted so far. When the dialog box disappears, the DBMS table is fully converted.
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When a model is changed, there is a Cancel button available. If you click Cancel, the Confirm Convert dialog box will close. Magic xpa will remember that the model was changed, so if the user runs the Options/Convert data source again, the user will see the screen again.
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Remember to modify variable pictures in forms to keep them consistent with any changes you make to the columns. Magic xpa cannot change the display pictures of variables displayed in task forms when changes are made to the Data repository. You can use Edit/Find and Replace/Find Reference (Ctrl+F) to find forms that may need changes.
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When possible, Magic xpa uses underlying database utilities for table conversion, for example using the SQL ALTER statement when the underlying database is SQL. See SQL Considerations.
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Data Source Properties
