Q: Clear Simple Data Writer csv file in jmeter Can you please tell me how to clear/reset the csv file written by Simple Data Writer everytime I run the thread?
Currently every time I run the thread, new results are getting appended to the end of the old results. I am a newbie, Thank you for your help.
Code
<?xml version="1.0" encoding="UTF-8"?>
<jmeterTestPlan version="1.2" properties="2.4" jmeter="2.9 r1437961">
<hashTree>
 <TestPlan guiclass="TestPlanGui" testclass="TestPlan" testname="Test Plan" enabled="true">
  <stringProp name="TestPlan.comments"></stringProp>
  <boolProp name="TestPlan.functional_mode">false</boolProp>
  <boolProp name="TestPlan.serialize_threadgroups">true</boolProp>
  <elementProp name="TestPlan.user_defined_variables" elementType="Arguments" guiclass="ArgumentsPanel" testclass="Arguments" testname="User Defined Variables" enabled="true">
    <collectionProp name="Arguments.arguments"/>
  </elementProp>
  <stringProp name="TestPlan.user_define_classpath"></stringProp>
</TestPlan>
<hashTree>
  <ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup" testname="Thread Group-1" enabled="true">
    <stringProp name="ThreadGroup.on_sample_error">continue</stringProp>
    <elementProp name="ThreadGroup.main_controller" elementType="LoopController" guiclass="LoopControlPanel" testclass="LoopController" testname="Loop Controller" enabled="true">
      <boolProp name="LoopController.continue_forever">false</boolProp>
      <stringProp name="LoopController.loops">1</stringProp>
    </elementProp>
    <stringProp name="ThreadGroup.num_threads">1</stringProp>
    <stringProp name="ThreadGroup.ramp_time">1</stringProp>
    <longProp name="ThreadGroup.start_time">1371005294000</longProp>
    <longProp name="ThreadGroup.end_time">1371005294000</longProp>
    <boolProp name="ThreadGroup.scheduler">false</boolProp>
    <stringProp name="ThreadGroup.duration"></stringProp>
    <stringProp name="ThreadGroup.delay"></stringProp>
  </ThreadGroup>
  <hashTree>
    <HTTPSamplerProxy guiclass="HttpTestSampleGui" testclass="HTTPSamplerProxy" testname="GET Patient list" enabled="true">
      <elementProp name="HTTPsampler.Arguments" elementType="Arguments" guiclass="HTTPArgumentsPanel" testclass="Arguments" testname="User Defined Variables" enabled="true">
        <collectionProp name="Arguments.arguments"/>
      </elementProp>
      <stringProp name="HTTPSampler.domain">http://sampleurl</stringProp>
      <stringProp name="HTTPSampler.port"></stringProp>
      <stringProp name="HTTPSampler.connect_timeout"></stringProp>
      <stringProp name="HTTPSampler.response_timeout"></stringProp>
      <stringProp name="HTTPSampler.protocol"></stringProp>
      <stringProp name="HTTPSampler.contentEncoding"></stringProp>
      <stringProp name="HTTPSampler.path">http://sampleurl</stringProp>
      <stringProp name="HTTPSampler.method">GET</stringProp>
      <boolProp name="HTTPSampler.follow_redirects">true</boolProp>
      <boolProp name="HTTPSampler.auto_redirects">false</boolProp>
      <boolProp name="HTTPSampler.use_keepalive">true</boolProp>
      <boolProp name="HTTPSampler.DO_MULTIPART_POST">false</boolProp>
      <boolProp name="HTTPSampler.monitor">false</boolProp>
      <stringProp name="HTTPSampler.embedded_url_re"></stringProp>
    </HTTPSamplerProxy>
    <hashTree>
      <AuthManager guiclass="AuthPanel" testclass="AuthManager" testname="HTTP Authorization Manager" enabled="true">
        <collectionProp name="AuthManager.auth_list">
          <elementProp name="" elementType="Authorization">
            <stringProp name="Authorization.url">http://sampurl</stringProp>
            <stringProp name="Authorization.username">samp</stringProp>
            <stringProp name="Authorization.password">samp</stringProp>
            <stringProp name="Authorization.domain"></stringProp>
            <stringProp name="Authorization.realm"></stringProp>
          </elementProp>
        </collectionProp>
      </AuthManager>
      <hashTree/>
      <RegexExtractor guiclass="RegexExtractorGui" testclass="RegexExtractor" testname="Regular Expression Extractor" enabled="true">
        <stringProp name="RegexExtractor.useHeaders">false</stringProp>
        <stringProp name="RegexExtractor.refname">Ary</stringProp>
        <stringProp name="RegexExtractor.regex">\[([^\]]+)\]</stringProp>
        <stringProp name="RegexExtractor.template">$1$</stringProp>
        <stringProp name="RegexExtractor.default"></stringProp>
        <stringProp name="RegexExtractor.match_number">1</stringProp>
      </RegexExtractor>
      <hashTree/>
      <RegexExtractor guiclass="RegexExtractorGui" testclass="RegexExtractor" testname="Parse ECN array" enabled="true">
        <stringProp name="RegexExtractor.useHeaders">false</stringProp>
        <stringProp name="RegexExtractor.refname">vals</stringProp>
        <stringProp name="RegexExtractor.regex">&quot;([^&quot;]+)&quot;</stringProp>
        <stringProp name="RegexExtractor.template">$1$</stringProp>
        <stringProp name="RegexExtractor.default"></stringProp>
        <stringProp name="RegexExtractor.match_number">-1</stringProp>
        <stringProp name="Scope.variable">PatientArray</stringProp>
        <stringProp name="Sample.scope">variable</stringProp>
      </RegexExtractor>
      <hashTree/>
    </hashTree>
    <DebugSampler guiclass="TestBeanGUI" testclass="DebugSampler" testname="RegX output" enabled="true">
      <boolProp name="displayJMeterProperties">false</boolProp>
      <boolProp name="displayJMeterVariables">true</boolProp>
      <boolProp name="displaySystemProperties">false</boolProp>
    </DebugSampler>
    <hashTree/>
    <ForeachController guiclass="ForeachControlPanel" testclass="ForeachController" testname="ForEach Controller" enabled="true">
      <stringProp name="ForeachController.inputVal">vals</stringProp>
      <stringProp name="ForeachController.returnVal">userid</stringProp>
      <boolProp name="ForeachController.useSeparator">true</boolProp>
    </ForeachController>
    <hashTree>
      <DebugSampler guiclass="TestBeanGUI" testclass="DebugSampler" testname="${userid}" enabled="true">
        <boolProp name="displayJMeterProperties">true</boolProp>
        <boolProp name="displayJMeterVariables">true</boolProp>
        <boolProp name="displaySystemProperties">false</boolProp>
      </DebugSampler>
      <hashTree>
        <ResultCollector guiclass="SimpleDataWriter" testclass="ResultCollector" testname="Simple Data Writer" enabled="true">
          <boolProp name="ResultCollector.error_logging">false</boolProp>
          <objProp>
            <name>saveConfig</name>
            <value class="SampleSaveConfiguration">
              <time>false</time>
              <latency>false</latency>
              <timestamp>false</timestamp>
              <success>false</success>
              <label>true</label>
              <code>false</code>
              <message>false</message>
              <threadName>false</threadName>
              <dataType>false</dataType>
              <encoding>false</encoding>
              <assertions>false</assertions>
              <subresults>false</subresults>
              <responseData>false</responseData>
              <samplerData>false</samplerData>
              <xml>false</xml>
              <fieldNames>false</fieldNames>
              <responseHeaders>false</responseHeaders>
              <requestHeaders>false</requestHeaders>
              <responseDataOnError>false</responseDataOnError>
              <saveAssertionResultsFailureMessage>false</saveAssertionResultsFailureMessage>
              <assertionsResultsToSave>0</assertionsResultsToSave>
            </value>
          </objProp>
          <stringProp name="filename">C:\Documents and Settings\valliammaim\My Documents\Downloads\apache-jmeter-2.9\apache-jmeter-2.9\bin\RegXoutput.csv</stringProp>
        </ResultCollector>
        <hashTree/>
      </hashTree>
    </hashTree>
    <ResultCollector guiclass="ViewResultsFullVisualizer" testclass="ResultCollector" testname="View Results Tree" enabled="true">
      <boolProp name="ResultCollector.error_logging">false</boolProp>
      <objProp>
        <name>saveConfig</name>
        <value class="SampleSaveConfiguration">
          <time>true</time>
          <latency>true</latency>
          <timestamp>true</timestamp>
          <success>true</success>
          <label>true</label>
          <code>true</code>
          <message>true</message>
          <threadName>true</threadName>
          <dataType>true</dataType>
          <encoding>false</encoding>
          <assertions>true</assertions>
          <subresults>true</subresults>
          <responseData>false</responseData>
          <samplerData>false</samplerData>
          <xml>false</xml>
          <fieldNames>false</fieldNames>
          <responseHeaders>false</responseHeaders>
          <requestHeaders>false</requestHeaders>
          <responseDataOnError>false</responseDataOnError>
          <saveAssertionResultsFailureMessage>false</saveAssertionResultsFailureMessage>
          <assertionsResultsToSave>0</assertionsResultsToSave>
          <bytes>true</bytes>
        </value>
      </objProp>
      <stringProp name="filename"></stringProp>
    </ResultCollector>
    <hashTree/>
    <ResultCollector guiclass="StatVisualizer" testclass="ResultCollector" testname="Aggregate Report" enabled="true">
      <boolProp name="ResultCollector.error_logging">false</boolProp>
      <objProp>
        <name>saveConfig</name>
        <value class="SampleSaveConfiguration">
          <time>true</time>
          <latency>true</latency>
          <timestamp>true</timestamp>
          <success>true</success>
          <label>true</label>
          <code>true</code>
          <message>false</message>
          <threadName>true</threadName>
          <dataType>true</dataType>
          <encoding>false</encoding>
          <assertions>true</assertions>
          <subresults>true</subresults>
          <responseData>false</responseData>
          <samplerData>false</samplerData>
          <xml>false</xml>
          <fieldNames>true</fieldNames>
          <responseHeaders>false</responseHeaders>
          <requestHeaders>false</requestHeaders>
          <responseDataOnError>false</responseDataOnError>
          <saveAssertionResultsFailureMessage>false</saveAssertionResultsFailureMessage>
          <assertionsResultsToSave>0</assertionsResultsToSave>
          <bytes>true</bytes>
        </value>
      </objProp>
      <stringProp name="filename">C:\Documents and Settings\valliammaim\My Documents\Downloads\apache-jmeter-2.9\apache-jmeter-2.9\bin\report.csv</stringProp>
      <boolProp name="useGroupName">true</boolProp>
    </ResultCollector>
    <hashTree/>
  </hashTree>
  <ThreadGroup guiclass="ThreadGroupGui" testclass="ThreadGroup" testname="Thread Group-2" enabled="true">
    <stringProp name="ThreadGroup.on_sample_error">continue</stringProp>
    <elementProp name="ThreadGroup.main_controller" elementType="LoopController" guiclass="LoopControlPanel" testclass="LoopController" testname="Loop Controller" enabled="true">
      <boolProp name="LoopController.continue_forever">false</boolProp>
      <stringProp name="LoopController.loops">1</stringProp>
    </elementProp>
    <stringProp name="ThreadGroup.num_threads">1</stringProp>
    <stringProp name="ThreadGroup.ramp_time">1</stringProp>
    <longProp name="ThreadGroup.start_time">1372725732000</longProp>
    <longProp name="ThreadGroup.end_time">1372725732000</longProp>
    <boolProp name="ThreadGroup.scheduler">false</boolProp>
    <stringProp name="ThreadGroup.duration"></stringProp>
    <stringProp name="ThreadGroup.delay"></stringProp>
  </ThreadGroup>
  <hashTree>
    <WhileController guiclass="WhileControllerGui" testclass="WhileController" testname="While Controller" enabled="true">
      <stringProp name="WhileController.condition">&quot;${userid}&quot; != &quot;&lt;EOF&gt;&quot;</stringProp>
    </WhileController>
    <hashTree>
      <LoopController guiclass="LoopControlPanel" testclass="LoopController" testname="Loop Controller" enabled="true">
        <boolProp name="LoopController.continue_forever">true</boolProp>
        <stringProp name="LoopController.loops">1</stringProp>
      </LoopController>
      <hashTree>
        <HTTPSamplerProxy guiclass="HttpTestSampleGui" testclass="HTTPSamplerProxy" testname="GET Patient" enabled="true">
          <elementProp name="HTTPsampler.Arguments" elementType="Arguments" guiclass="HTTPArgumentsPanel" testclass="Arguments" testname="User Defined Variables" enabled="true">
            <collectionProp name="Arguments.arguments"/>
          </elementProp>
          <stringProp name="HTTPSampler.domain">http://sampurl/${patientECN}</stringProp>
          <stringProp name="HTTPSampler.port"></stringProp>
          <stringProp name="HTTPSampler.connect_timeout"></stringProp>
          <stringProp name="HTTPSampler.response_timeout"></stringProp>
          <stringProp name="HTTPSampler.protocol"></stringProp>
          <stringProp name="HTTPSampler.contentEncoding"></stringProp>
          <stringProp name="HTTPSampler.path">http://sampleurl/${patientECN}</stringProp>
          <stringProp name="HTTPSampler.method">GET</stringProp>
          <boolProp name="HTTPSampler.follow_redirects">true</boolProp>
          <boolProp name="HTTPSampler.auto_redirects">false</boolProp>
          <boolProp name="HTTPSampler.use_keepalive">true</boolProp>
          <boolProp name="HTTPSampler.DO_MULTIPART_POST">false</boolProp>
          <boolProp name="HTTPSampler.monitor">false</boolProp>
          <stringProp name="HTTPSampler.embedded_url_re"></stringProp>
        </HTTPSamplerProxy>
        <hashTree>
          <ConstantTimer guiclass="ConstantTimerGui" testclass="ConstantTimer" testname="Constant Timer" enabled="true">
            <stringProp name="ConstantTimer.delay">100</stringProp>
          </ConstantTimer>
          <hashTree/>
          <AuthManager guiclass="AuthPanel" testclass="AuthManager" testname="HTTP Authorization Manager" enabled="true">
            <collectionProp name="AuthManager.auth_list">
              <elementProp name="" elementType="Authorization">
                <stringProp name="Authorization.url">http://sampurl/${userid}</stringProp>
                <stringProp name="Authorization.username">sample</stringProp>
                <stringProp name="Authorization.password">sample</stringProp>
                <stringProp name="Authorization.domain"></stringProp>
                <stringProp name="Authorization.realm"></stringProp>
              </elementProp>
            </collectionProp>
          </AuthManager>
          <hashTree/>
        </hashTree>
      </hashTree>
      <CSVDataSet guiclass="TestBeanGUI" testclass="CSVDataSet" testname="CSV Data Set Config" enabled="true">
        <stringProp name="delimiter">,</stringProp>
        <stringProp name="fileEncoding"></stringProp>
        <stringProp name="filename">RegXoutput.csv</stringProp>
        <boolProp name="quotedData">true</boolProp>
        <boolProp name="recycle">false</boolProp>
        <stringProp name="shareMode">All threads</stringProp>
        <boolProp name="stopThread">true</boolProp>
        <stringProp name="variableNames">userid</stringProp>
      </CSVDataSet>
      <hashTree/>
    </hashTree>
    <ResultCollector guiclass="StatVisualizer" testclass="ResultCollector" testname="Aggregate Report" enabled="true">
      <boolProp name="ResultCollector.error_logging">false</boolProp>
      <objProp>
        <name>saveConfig</name>
        <value class="SampleSaveConfiguration">
          <time>true</time>
          <latency>true</latency>
          <timestamp>true</timestamp>
          <success>true</success>
          <label>true</label>
          <code>true</code>
          <message>true</message>
          <threadName>true</threadName>
          <dataType>true</dataType>
          <encoding>false</encoding>
          <assertions>true</assertions>
          <subresults>true</subresults>
          <responseData>false</responseData>
          <samplerData>false</samplerData>
          <xml>false</xml>
          <fieldNames>false</fieldNames>
          <responseHeaders>false</responseHeaders>
          <requestHeaders>false</requestHeaders>
          <responseDataOnError>false</responseDataOnError>
          <saveAssertionResultsFailureMessage>false</saveAssertionResultsFailureMessage>
          <assertionsResultsToSave>0</assertionsResultsToSave>
          <bytes>true</bytes>
        </value>
      </objProp>
      <stringProp name="filename"></stringProp>
    </ResultCollector>
    <hashTree/>
    <ResultCollector guiclass="ViewResultsFullVisualizer" testclass="ResultCollector" testname="View Results Tree" enabled="true">
      <boolProp name="ResultCollector.error_logging">false</boolProp>
      <objProp>
        <name>saveConfig</name>
        <value class="SampleSaveConfiguration">
          <time>true</time>
          <latency>true</latency>
          <timestamp>true</timestamp>
          <success>true</success>
          <label>true</label>
          <code>true</code>
          <message>true</message>
          <threadName>true</threadName>
          <dataType>true</dataType>
          <encoding>false</encoding>
          <assertions>true</assertions>
          <subresults>true</subresults>
          <responseData>false</responseData>
          <samplerData>false</samplerData>
          <xml>false</xml>
          <fieldNames>false</fieldNames>
          <responseHeaders>false</responseHeaders>
          <requestHeaders>false</requestHeaders>
          <responseDataOnError>false</responseDataOnError>
          <saveAssertionResultsFailureMessage>false</saveAssertionResultsFailureMessage>
          <assertionsResultsToSave>0</assertionsResultsToSave>
          <bytes>true</bytes>
        </value>
      </objProp>
      <stringProp name="filename"></stringProp>
    </ResultCollector>
    <hashTree/>
  </hashTree>
</hashTree>




A: *

*The *Simple Data Writer has no property that lets you truncate the file which is a pity. Alternatively you could put a timestamp in teh filename to make sure it is empty at the start of the test (like RegXoutput${__time(yyyyMMdd-HHmm,)}.csv) and cleanup afterwards or use a BeanShell script to truncate the file.* – rsp 2 days ago

*Thank you rsp timestamp solution is the best alternative for this question. 
