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OCT 24 / 9AM ET Register nowHow to Use Alter Hints
After the RDM Logical Model (tables and relationships between them) is defined, deployed, and filled with data, most changes to it require adding an additional configuration file alter-hints.xml
to the configuration ZIP file before deploying changes to the model (see how-to-deploy-an-rdm-web-app-configuration.adoc).
Alter hints are necessary to preserve permissions and data on existing objects or pre-fill data on a new column that must not be empty.
Alter hints structure
The alter-hints.xml
file has the following structure:
<alter-hints>
<entities>
<entity sourceName="tableA" targetName="tableB">
<columns>
<column targetName="columnB" expression="columnA" permissionsFrom="columnA"
/>
</columns>
</entity>
</entities>
</alter-hints>
Element | Attribute | Description | ||
---|---|---|---|---|
entity |
sourceName |
Old name of the table. |
||
entity |
targetName |
New name of the table. |
||
column |
targetName |
Name of the new column. |
||
column |
expression |
Expression used to fill the data.
|
||
column |
permissionsFrom |
Name of the column from which to inherit viewing and editing rights. |
The following sections present practical examples.
Add a new string column
The following example shows alter-hints.xml
configuration for adding a new column of the string type, filling it with a constant value, and inheriting viewing and editing rights from a different column:
<alter-hints>
<entities>
<entity sourceName="tableA" targetName="tableA">
<columns>
<column
targetName="newStringColumn"
expression="'string enclosed in single quotes'"
permissionsFrom="anotherStringColumn"
/>
</columns>
</entity>
</entities>
</alter-hints>
Add a new integer column
The following example shows alter-hints.xml
configuration for adding a new column of the integer-type domain, filling it with a constant value, and inheriting viewing and editing rights from a different column:
<alter-hints>
<entities>
<entity sourceName="tableA" targetName="tableA">
<columns>
<column
targetName="newIntegerColumn"
expression="0"
permissionsFrom="anotherIntegerColumn"
/>
</columns>
</entity>
</entities>
</alter-hints>
Add a new datetime column
The following example shows alter-hints.xml
configuration for adding two new columns of the datetime-type domain, filling them with a constant value, and inheriting viewing and editing rights from a different column.
This example can be used when transforming a table to using business dates (see Tables, section Business date columns).
<alter-hints>
<entities>
<entity sourceName="tableA" targetName="tableA">
<columns>
<column
targetName="VERSION_FROM"
expression="to_date('2015-01-01 00:00:00', 'YYYY-MM-DD HH24:MI:SS')"
permissionsFrom="ID_tableA"
/>
<column
targetName="VERSION_TO"
expression="to_date('2015-12-31 00:00:00', 'YYYY-MM-DD HH24:MI:SS')"
permissionsFrom="ID_tableA"
/>
</columns>
</entity>
</entities>
</alter-hints>
Change column data type
The following example shows alter-hints.xml
configuration for changing a column data type from integer to string.
In reality, a new column is created in the RDM repository; therefore, viewing and editing rights are configured to be inherited too:
<alter-hints>
<entities>
<entity sourceName="tableA" targetName="tableA">
<columns>
<column
targetName="columnA"
expression="to_char(columnA)"
permissionsFrom="columnA"
/>
</columns>
</entity>
</entities>
</alter-hints>
Renaming a column
The following example shows alter-hints.xml
configuration for renaming a column.
In reality, a new column is created in the RDM repository; therefore, viewing and editing rights are configured to be inherited too:
<alter-hints>
<entities>
<entity sourceName="tableA" targetName="tableA">
<columns>
<column
targetName="NewColumnA"
expression="OldColumnA"
permissionsFrom="OldColumnA"
/>
</columns>
</entity>
</entities>
</alter-hints>
Renaming the foreign key column
Renaming a foreign key column is necessary when changing the relationship name between tables: child tables contain foreign key columns to parent tables and are named using the following naming convention: [prefix]_[relationship_name], where prefix is set to GENERATEDPK
.
The following example shows alter-hints.xml
configuration for renaming a foreign key column:
<alter-hints>
<entities>
<entity sourceName="tableA" targetName="tableA">
<columns>
<column
targetName="GENERATEDPK_NewRelationshipName"
expression="GENERATEDPK_OldRelationshipName"
/>
</columns>
</entity>
</entities>
</alter-hints>
Rename a table
The following example shows alter-hints.xml
configuration for renaming a table.
A new table is created in the database, therefore all table columns inherit their own data and permissions automatically.
For this reason, you should not define the columns
element:
<alter-hints>
<entities>
<entity sourceName="tableA" targetName="tableB">
</entity>
</entities>
</alter-hints>
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