« prev index next »

5. Database Schema extraction

• Principle
• Details of dbmetadata-maven-plugin
• Simple Usage

Principle

The database schema extraction is performed by the extract-metadata goal of the dbmetadata-maven-plugin, a Maven plugin provided by Jaxio.

This plugin connects to a relational database using JDBC, retrieves the database schema metadata and write it into an XML file named metadata.xml.

Note

The metadata file produced by the dbmetadata plugin is not meant to be edited manually. If you need to change some settings, you should either change your database schema or use Celerio’s configuration file.

While pretty straightforward the schema extraction may take several minutes on large database schemas (e.g. more than 200 tables). To prevent useless extraction , the simplest approach is to declare a Maven profile dedicated to database extraction and activate it only when needed (i.e. each time you modify the database schema).

The metadata.xml file produced by this plugin is used by Celerio’s generate goal.

Details of dbmetadata-maven-plugin

Full name

• name: com.jaxio.celerio:dbmetadata-maven-plugin
• goal: extract-metadata
• maven phase: generate-sources

Attributes

skip

• expression: celerio-maven-plugin.skip
• default value: false
• description: Should the database meta data extraction be skipped ? This is a common pattern in Maven, where you can skip plugins using profiles to fully adapt your build.

jdbcDriver

• expression: jdbc.driver
• description: Set the JDBC driver class
• example: org.postgresql.Driver

jdbcUrl

• expression: jdbc.url
• description: Set the JDBC url to connect to your database. Make sure that you connect with enough privileges to access the meta data information.
• example: jdbc:h2:~/.h2/sampledatabase

jdbcUser

• expression: jdbc.user
• description: Set the JDBC user, this user needs to have the privilege to access the database metadata.

jdbcPassword

• expression: jdbc.password
• description: Set the JDBC password.

jdbcCatalog

• expression: jdbc.catalog
• description: Set the JDBC catalog.

jdbcOracleRetrieveRemarks

• expression: jdbc.oracleRetrieveRemarks
• default value: false
• description: Should the Oracle remarks be retrieved ? Please note that this will impact the speed of the reverse engineering of your database.

jdbcOracleRetrieveSynonyms

• expression: jdbc.oracleRetrieveSynonyms
• default value: true
• description: Should the synonyms be retrieved ?

jdbc.reverseIndexes

• expression: jdbc.reverseIndexes
• default value: true
• description: When false, disable completely reverse of indexes. Can be useful when reversing large database full of data as reversing indexes can be slow.

jdbc.reverseOnlyUniqueIndexes

• expression: jdbc.reverseOnlyUniqueIndexes
• default value: true
• description: When true, reverse only indexes for unique values; when false, reverse indexes regardless of whether unique or not. Can be useful when reversing large database full of data as reversing indexes can be slow.

jdbcReverseViews

• expression: jdbc.reverseViews
• default value: false
• description: Should this plugin also reverse VIEWS?

jdbcSchema

• expression: jdbc.schema
• description: Set the JDBC schema.

targetFilename

• expression: maven-metadata-plugin.targetFilename
• default value: ${basedir}/src/main/config/celerio-maven-plugin/metadata.xml
• description: The fully qualified name of the XML file created by this plugin.

jdbcTableNamePatterns

• type: List
• default value: %
• description: In case DB reverse is too slow you may use this configuration to filter out tables during DB reverse phase. By default Celerio reverses all the tables and you can filter them out afterward, during code generation phase.

Simple Usage

In your pom.xml, declare as properties the necessary expressions that the plugin needs to connect to your database and reverse it. Then create a dedicated profile to execute the plugin.

<properties>
  <jdbc.groupId>com.h2database</jdbc.groupId>
  <jdbc.artifactId>h2</jdbc.artifactId>
  <jdbc.version>1.3.167</jdbc.version>
  <jdbc.driver>org.h2.Driver</jdbc.driver>
  <jdbc.url>jdbc:h2:~/.h2/mydbname;MVCC=TRUE</jdbc.url>
  <jdbc.user>admin</jdbc.user>
  <jdbc.password></jdbc.password>
</properties>

<!-- skip -->
	
<profile>
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <!-- Extract the database metadata -->
  <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -->
  <id>metadata</id>
  <build>
    <defaultGoal>generate-sources</defaultGoal>
    <plugins>
      <plugin>
        <groupId>com.jaxio.celerio</groupId>
        <artifactId>dbmetadata-maven-plugin</artifactId>
        <version>${celerio-maven-plugin.version}</version>
        <executions>
          <execution>
            <id>Extract the database schema.</id>
            <goals>
              <goal>extract-metadata</goal>
          	</goals>
            <configuration>
              <jdbcTableNamePatterns><!-- pre-filtering, configurable since 4.0.7, optional, will be % by default -->
                <param>%</param> <!-- "%" means match any substring of 0 or more characters, and "_" means match any one character -->
              </jdbcTableNamePatterns>
            </configuration>						
          </executions>
          <dependencies>
            <dependency>
              <groupId>${jdbc.groupId}</groupId>
              <artifactId>${jdbc.artifactId}</artifactId>
              <version>${jdbc.version}</version>
            </dependency>
        </dependencies>
      </plugin>
    </plugins>
  </build>
</profile>