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Importing XML data using noChecks

To ensure that any new data does not conflict with existing data, Proximity’s import process restricts when and how you can add additional elements to an existing database. In many instance, however, careful data management can eliminate such conflicts. In such cases, users can override the default import restrictions by setting the noChecks import option to true.

When noChecks is true, Proximity makes no checks to see if the imported data conflicts with the existing database. If imported objects or links already exist in the database, Proximity creates duplicate entries for these items. When noChecks is false or not specified, adding new objects or links to a database that already contains such items results in an error. You can also use the noChecks option to import additional values for previously defined attributes (an error without this option). The only check in this case is ensuring that the “new” attribute is of the same type as the previously defined attribute.

When noChecks is true, Proximity automatically recodes container identifiers when imported containers conflict with containers already present in the database. For example, if the database already has a container with an ID of 2, and the XML data file to be imported also includes a container with an ID of 2, the import process assigns a new, non-conflicting identifier to the imported container. Any associated data (container attributes and nesting relationships) are similarly recoded.

The following exercise adds a small number of new link_tag attribute values to the database. The new values are added solely for illustrative purposes; they are not used in later Tutorial exercises.

Exercise 3.3. Importing additional link_tag attribute values:

Before beginning, make sure that you are serving the ProxWebKB database (created in Exercise 3.1) using Mserver. You must have completed Exercise 3.1 before running the current exercise. Data files must be on the same machine as that serving the database.

  1. Try to import the new link_tag attribute values without using the noChecks option. (Substitute the appropriate port number if you are using a different port.) 

    > bin/import-xml.sh localhost:30000 \
  $PROX_HOME/doc/user/tutorial/examples/more-linktag-values.xml

    Proximity attempts to import the new attribute values, but reports an error because the link_tag attribute already exists. 

    ERROR app.ImportXMLApp: java.lang.IllegalArgumentException:
Attribute already exists in the database: link_tag. You may use the
noChecks flag if you want to ignore this check.

  2. Import the additional link_tag attribute values, specifying that noChecks is true. 

    > bin/import-xml.sh localhost:30000 \
  $PROX_HOME/doc/user/tutorial/examples/more-linktag-values.xml true

    When the import process is finished, Proximity reports on the number of database entities created (leading information showing elapsed time and execution thread has been omitted from the trace for brevity): 

    INFO  app.ImportXMLApp: * importing database from
   /proximity/doc/user/tutorial/examples/more-linktag-values.xml
   NOT CHECKING FOR DUPLICATES 
INFO  app.ImportXMLApp: * converting xml to bulk import text files;
   dir: /tmp/prox-xml-import62294
INFO  app.ImportXMLApp:   attributes
INFO  app.ImportXMLApp:   attribute: link_tag, L, str
INFO  app.ImportTextApp: * importing database from /tmp/prox-xml-import62294
INFO  app.ImportTextApp:   Loading object table
INFO  app.ImportTextApp:   Loading link table
INFO  app.ImportTextApp:   Loading attributes
INFO  app.ImportTextApp:   Loading attribute: av_0
INFO  app.ImportTextApp:   Loading containers
INFO  app.ImportTextApp: * done importing
INFO  app.ImportXMLApp: * done importing; counts:
   0 objects, 0 links, 1 attributes, 5 attribute values,
   0 containers, 0 subgraph items

    Note that the start of the trace includes a warning that the import process is not checking for duplicates.

  3. If you want, examine link 1 in the Proximity Database Browser to see its attribute values. (A summary of steps for examining link 1’s attribute values is included, below. See Chapter 4, Exploring Data for complete information on using the Proximity Database Browser.)

    1. From the Proximity Database Browser start page, click Links.

    2. Click 1.

    3. Click attrs.

    Because link 1 already had a value of “OFFSITE” for the link_tag attribute, the new data is added as an additional value for this attribute.

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