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(Out of) Memory

If you get an OutOfMemoryError, first increase the Java heap size by a -Xmx environment setting (e.g. by adding -Xmx1024m to the BENERATOR_OPTS in the script files).

Another potential cause for OutOfMemoryErrors is the application of distributions to very large data sets. Most sequences and all other types of distribution require the source data to fit into RAM. So either use an 'unlimited' sequence like 'expand', 'repeat' or 'randomWalk' or simply repeat data set iteration by adding cyclic="true" to the configuration.

temp Directory

In some environments, the temp directory has a very restrictive disk quota. If you need more space for data generation, you can specify another directory by the environment setting (e.g. by adding to the BENERATOR_OPTS in the script files)

File Encoding

If no file encoding was specified, benerator uses the default file encoding of the system it runs on - except if the file itself contains encoding info (like XML).

If all used files have the same encoding and it is different to your system's encoding, you can change set benerator's default encoding by the -Dfile.encoding environment setting (e.g. by adding -Dfile.encoding=iso-8859-1 to the BENERATOR_OPTS in the script files)

When generating data in heterogeneous environments, it is good practice setting the defaultEncoding property of the benerator descriptor file's root element. If only single files have a different encoding, you can specify an encoding property for all built-in file importers and file-based consumers.

A typical error that may arise from wrong file encoding configuration is that file import (e.g. for a CSV file) stops before the end of file is reached.


Benerator logs its event using slf4j as a logging facade to integrate with the logging tools used by libraries which are used by Benerator. As logging implementation, Apache Log4j 2 is used. For troubleshooting, it is useful to check and fine-tune logging configuration for tracking down your issue. This is done by editing the log4j2.xml file in your BENERATOR_HOME/bin directory. Some interesting logging categories to start with:

Set a category to debug for getting detailed information about its execution. The most important log categories are:

name description
com.rapiddweller.benerator.main Events of benerator's main classes, e.g. detailed information about which entities are currently generated
com.rapiddweller.benerator.STATE generator state handling for information which component generator caused termination of the composite generator
com.rapiddweller.benerator.factory Creating generators from descriptor information
com.rapiddweller.benerator Top-level directory for all generators and main classes
com.rapiddweller.SQL SQL commands, e.g. DDL, queries, inserts, updates
com.rapiddweller.JDBC JDBC operations, e.g. connection / transaction handling
com.rapiddweller.jdbacl.model.jdbc Database meta data import
com.rapiddweller.platform.db All database related information that does not fit into the SQL or JDBC category
com.rapiddweller.platform.xml XML-related activities
com.rapiddweller.domain benerator domain packages
com.rapiddweller.model descriptor related information
com.rapiddweller.common low-level operations like data conversion

Locating Errors

When configuring data generation you are likely to encounter error messages.

Depending on the settings it may be difficult to find out what caused the problem. For tracking database-related errors, set batch="false" in your <database> setup and use pagesize="1" in the <generate>. These are default settings, so you do not need to specify them explicitly if you did not change the default.

If that alone does not help, set the log category com.rapiddweller.benerator.main to debug level to find out which element caused the error. If there is a stack trace, check it to get a hint of which part of the element's generation went wrong. If that does not help, remove one attribute/reference/id after the other for finding the actual troublemaker. If you still cannot solve the problem, post a message in the benerator forum. You can check out the benerator sources from the SVN source repository, open it in Eclipse and debug through the code.

Database Privilege Problems

When importing database metadata, you might encounter exceptions when Benerator tries to get metadata of catalogs or schemas it has no access privileges to.

Usually can fix this by choosing the right schema for your database, e.g.

<database id="db" ... schema="PUBLIC" />

If you are not sure which schema is applicable in your case, edit the logging configuration in log4j.xml (as described above) and set the category com.rapiddweller.platform.db to debug.

You will then get a list of schemas as Benerator scans the database metadata, e.g. for an Oracle system:

06:03:45,203 DEBUG [DBSystem] parsing metadata...
06:03:45,203 DEBUG [JDBC] opening connection to jdbc:oracle:thin:@
06:03:45,226 DEBUG [JDBC] Created connection #4: oracle.jdbc.driver.T4CConnection@741827d1
06:03:45,385 DEBUG [JDBC] opening connection to jdbc:oracle:thin:@
06:03:45,417 INFO [JDBCDBImporter] Importing database metadata. Be patient, this may take some time...
06:03:45,417 DEBUG [JDBCDBImporter] Product name: Oracle
06:03:45,419 INFO [JDBCDBImporter] Importing catalogs
06:03:45,430 INFO [JDBCDBImporter] Importing schemas
06:03:45,438 DEBUG [JDBCDBImporter] found schema ANONYMOUS
06:03:45,438 DEBUG [JDBCDBImporter] found schema DBSNMP
06:03:45,438 DEBUG [JDBCDBImporter] found schema DIP
06:03:45,438 DEBUG [JDBCDBImporter] found schema FLOWS_FILES
06:03:45,439 DEBUG [JDBCDBImporter] found schema FLOWS_020100
06:03:45,439 DEBUG [JDBCDBImporter] found schema HR
06:03:45,439 DEBUG [JDBCDBImporter] found schema MDSYS
06:03:45,440 DEBUG [JDBCDBImporter] found schema OUTLN
06:03:45,440 DEBUG [JDBCDBImporter] found schema SHOP
06:03:45,440 DEBUG [JDBCDBImporter] importing schema SHOP
06:03:45,441 DEBUG [JDBCDBImporter] found schema SYS
06:03:45,441 DEBUG [JDBCDBImporter] found schema SYSTEM
06:03:45,441 DEBUG [JDBCDBImporter] found schema TSMSYS
06:03:45,441 DEBUG [JDBCDBImporter] found schema XDB

Cross-checking this with your access information should make it easy to figure out which one is appropriate in your case.

See the Usual Database Settings.

Constraint Violations

Some constraint violations may arise when using database batch with nested create-entities. Switch batch off. If the problem does not occur any more, stick with non-batch generation. Otherwise, you need further investigation. When using Oracle, a constraint violation typically looks like this:

java.sql.SQLException: ORA-00001: Unique Constraint (MYSCHEMA.SYS_C0011664) violated

It contains a constraint name you can look up on the database like this:

select * from user_constraints where constraint_name like '%SYS_C0011541%'

The query result will tell you the table name and the constraint type. The constraint types are encoded as follows:

P: Primary key constraint

U: Unique constraint

R: Foreign key constraint

'value too large for column' in Oracle

Depending on the character set, oracle may report a multiple of the real column with, e.g. 80 instead of 20. So, automatic generation of varchar2 columns may fail. This typically results in Exceptions like this:

java.sql.SQLException: ORA-12899: value too large for column "SCHEM"."TBL"."COL" (actual: 40, maximum: 10)

This is Oracle bug #4485954, see and .

The solution is using the newest JDBC driver, at least or 11.0. BTW: It is backward compatible with the Oracle 9 databases.

Time is cut off in Oracle dates

Oracle changed back and forth the mapping of internal types to JDBC times in Oracle 8 and 11, the mapping in Oracle 9 and 10 is wrong, see . In order to fix the behaviour, use the newest available Oracle 11 JDBC driver you can get, it is backward compatible down to Oracle 9 and provides a proper mapping of the date type for all Oracle database versions.

Composite Keys

Benerator expects single-valued ids. It does not automatically support composite keys and composite references.

Since composite keys typically have a business meaning, most composite keys cannot be automatically generated. So there is no need to support this.

If you encounter a composite key, manually configure how to create each key component.

Importing Excel Sheets

For a beginner it is sometimes confusing, how Benerator handles imported Excel sheets. For this task it completely relies on the cell type configured in the original sheet. So if you have a Date cell in the Excel sheet and format it as number or text, benerator will interpret it as double or string.

Another popular error comes from columns that contain long code numbers and have the default format: They are imported as numbers and e.g. leading zeros are lost. In such case explicitly format the column as text in Excel.

Apache POI represents all numbers as variables of type double. So there are numbers which are simple in decimal format but not so in binary: when importing the number 1.95 from an Excel sheet, the user gets a value of 1.95000000002. For now, you need to round the values yourself, e.g. by a converter.

Number Generation on Oracle

When generating very large decimal values (> in an Oracle database you may observe that smaller numbers are written to the database, losing some trailing zeros or even cutting the whole number to a decimal with one prefix digit and several fractional digits. This results from a bug in Oracles older JDBC drivers and can be fixed by using the newest driver version (note that you can even use 11.x JDBC drivers for 10.x databases).

Unknown Column Type

If your application makes use of a database's proprietary column types, you may run into an exception when Benerator encounters it. If you know how to create and handle data for this column type, you can do so by configuring the database to accept unknown column types :

<database ... acceptUnknownColumnTypes="true">

Table 'X' not found in the expected catalog 'Y' and schema 'Z'

This message tells you, that you database configuration is wrong. Check and fix the 'schema' and 'catalog' settings in your database configuration, e.g.

<database  catalog="main" schema="Z" />

or your environment configuration, e.g.




Note: On most systems (e.g. Oracle, HSQL) no catalog needs to be specified.

Method isApplicationDetached() not found in class Xyz

See 'Migration from 1.1.x to 3.0.0'.