Error while executing operator "Read Database" with the name "Read total instances" in Java

akochsic · January 2018

Hello,

I am new to rapidminer and I am trying to get an old program running. It is an Java project using the rapidminer command line mode.

Since it is an older project it was developed with a rapidminer version 5.x. I tried to run it with several newer versions, which are available with maven.
While running the program throws following error:
com.rapidminer.operator.UserError: The dummy operator Read total instances (replacing null) cannot be executed.

The process it self is runnable inside rapidminer studio.

I also tried playing aroung with the versioning in rapidminer studio, but with no success.

You can find the process attached.

I don't know what my mistake could be. Hopefully you have an idea.

Thanks

sgenzer · January 2018

hello @akochsic - so dummy operators are created usually when you are using an operator in your process that RapidMiner does not recognize. I've not heard of "Read Total Instances" before...

Scott

akochsic · January 2018

Hello @sgenzer,

thanks for your quick reply.

Sorry for the misunderstanding. "Read total instances" is the name of the operator "Read Database".

The operator is configured as follows:

<operator activated="true" class="jdbc_connectors:read_database" compatibility="8.0.001" expanded="true" height="68" name="Read total instances" width="90" x="179" y="210">
<parameter key="define_connection" value="predefined"/>
<parameter key="connection" value="local (master)"/>
<parameter key="database_system" value="MySQL"/>
<parameter key="define_query" value="query"/>
<parameter key="query" value="(SELECT `size`
FROM `category_sizes`
WHERE category=? LIMIT 1)
UNION (SELECT 0); -- default value in case category is not in table."/>
<parameter key="use_default_schema" value="true"/>
<parameter key="prepare_statement" value="true"/>
<enumeration key="parameters">
<parameter key="parameter" value="VARCHAR.%{category}"/>
</enumeration>
<parameter key="datamanagement" value="double_array"/>
<parameter key="data_management" value="auto"/>
</operator>

Thanks

sgenzer · January 2018

yes those look like parameters from an old Read Database operator. I'd look at the XML created from a new Read Database operator and xfer your settings & query. For example:

  <operator activated="true" class="process" compatibility="8.0.001" expanded="true" name="Process">
    <process expanded="true">
      <operator activated="true" class="jdbc_connectors:read_database" compatibility="8.0.001" expanded="true" height="68" name="Read Database" width="90" x="246" y="34">
        <parameter key="connection" value="MyCoolSQLDB"/>
        <parameter key="query" value="SELECT `bar`&#10;FROM `foo`"/>
        <enumeration key="parameters"/>
      </operator>
      <portSpacing port="source_input 1" spacing="0"/>
      <portSpacing port="sink_result 1" spacing="0"/>
    </process>
  </operator>

Note you need to set up a database connection first in order to make this work.

Scott

akochsic · January 2018

I tried creating a new repository with a new process and a new "Read database" operator, but I am still facing the same error. I can't really see any difference in the operator I am using and the example code you posted, since also both have the compatibility set to version 8.0.001.

The process is still running perfectly in Rapidminer Studio. I am only facing the issue using Java with the Command Line Execution mode.

This is the new example process I tried now:

<?xml version="1.0" encoding="UTF-8"?><process version="8.0.001">
  <context>
    <input/>
    <output/>
    <macros/>
  </context>
  <operator activated="true" class="process" compatibility="8.0.001" expanded="true" name="Process">
    <parameter key="logverbosity" value="init"/>
    <parameter key="random_seed" value="2001"/>
    <parameter key="send_mail" value="never"/>
    <parameter key="notification_email" value=""/>
    <parameter key="process_duration_for_mail" value="30"/>
    <parameter key="encoding" value="SYSTEM"/>
    <process expanded="true">
      <operator activated="true" class="jdbc_connectors:read_database" compatibility="8.0.001" expanded="true" height="68" name="Read Database (2)" width="90" x="179" y="289">
        <parameter key="define_connection" value="predefined"/>
        <parameter key="connection" value="local (master)"/>
        <parameter key="database_system" value="MySQL"/>
        <parameter key="define_query" value="query"/>
        <parameter key="query" value="SELECT `s`&#10;FROM `article_categories`"/>
        <parameter key="use_default_schema" value="true"/>
        <parameter key="prepare_statement" value="false"/>
        <enumeration key="parameters"/>
        <parameter key="datamanagement" value="double_array"/>
        <parameter key="data_management" value="auto"/>
      </operator>
      <portSpacing port="source_input 1" spacing="0"/>
      <portSpacing port="sink_result 1" spacing="0"/>
    </process>
  </operator>
</process>

sgenzer · January 2018

hmm sorry - don't know what to tell you. Just curious - why are you insisting on using the command line execution rather than setting up a RM Server?

Scott

akochsic · January 2018

Since it's an rather old project, I tried setting it up without the need changing it too much. Maybe it would be a good idea to try working with an RM Server. Thanks for your help.

I now found a way to get the old project running: I built the rapidminer.jar from the rapidminer5 repository and added it as an external jar to the project. This is obviously not a perfect solution, but a workaround. With the old rapidminer version I don't get any error messages.

Error while executing operator "Read Database" with the name "Read total instances" in Java

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