title: spark - No schema defined, and no Parquet data file or summary file found under
body: <p>first I started   </p>
  
  <pre><code>$SPARK_HOME/bin/pyspark
  </code></pre>
  
  <p>and write this code   </p>
  
  <pre><code>sqlContext.load("jdbc", url="jdbc:mysql://IP:3306/test", driver="com.mysql.jdbc.Driver", dbtable="test.test_tb")
  </code></pre>
  
  <p><strong>when I write only dbtable= "test_db", the error is same.</strong></p>
  
  <p>After this error is occurred,</p>
  
  <blockquote>
    <p>py4j.protocol.Py4JJavaError: An error occurred while calling o66.load.
    : java.lang.AssertionError: assertion failed: No schema defined, and no Parquet data file or summary file found under .
    at scala.Predef$.assert(Predef.scala:179)
    at org.apache.spark.sql.parquet.ParquetRelation2$MetadataCache.org$apache$spark$sql$parquet$ParquetRelation2$MetadataCache$$readSchema(newParquet.scala:429)
    .....</p>
  </blockquote>
  
  <p>why this error was occured??
  I want to know and solve this problem.</p>
  
  <p>thank you.</p>