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| <div class="subTitle">org.apache.hawq.pxf.plugins.hdfs</div> |
| <h2 title="Class HdfsAtomicDataAccessor" class="title">Class HdfsAtomicDataAccessor</h2> |
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| <ul class="inheritance"> |
| <li>java.lang.Object</li> |
| <li> |
| <ul class="inheritance"> |
| <li><a href="../../../../../../org/apache/hawq/pxf/api/utilities/Plugin.html" title="class in org.apache.hawq.pxf.api.utilities">org.apache.hawq.pxf.api.utilities.Plugin</a></li> |
| <li> |
| <ul class="inheritance"> |
| <li>org.apache.hawq.pxf.plugins.hdfs.HdfsAtomicDataAccessor</li> |
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| </dl> |
| <dl> |
| <dt>Direct Known Subclasses:</dt> |
| <dd><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/QuotedLineBreakAccessor.html" title="class in org.apache.hawq.pxf.plugins.hdfs">QuotedLineBreakAccessor</a></dd> |
| </dl> |
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| <br> |
| <pre>public abstract class <span class="typeNameLabel">HdfsAtomicDataAccessor</span> |
| extends <a href="../../../../../../org/apache/hawq/pxf/api/utilities/Plugin.html" title="class in org.apache.hawq.pxf.api.utilities">Plugin</a> |
| implements <a href="../../../../../../org/apache/hawq/pxf/api/ReadAccessor.html" title="interface in org.apache.hawq.pxf.api">ReadAccessor</a></pre> |
| <div class="block">Base class for enforcing the complete access of a file in one accessor. |
| Since we are not accessing the file using the splittable API, but instead are |
| using the "simple" stream API, it means that we cannot fetch different parts |
| (splits) of the file in different segments. Instead each file access brings |
| the complete file. And, if several segments would access the same file, then |
| each one will return the whole file and we will observe in the query result, |
| each record appearing number_of_segments times. To avoid this we will only |
| have one segment (segment 0) working for this case - enforced with |
| isWorkingSegment() method. Naturally this is the less recommended working |
| mode since we are not making use of segment parallelism. HDFS accessors for |
| a specific file type should inherit from this class only if the file they are |
| reading does not support splitting: a protocol-buffer file, regular file, ...</div> |
| </li> |
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| <th class="colLast" scope="col">Field and Description</th> |
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| <tr class="altColor"> |
| <td class="colFirst"><code>protected java.io.InputStream</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/HdfsAtomicDataAccessor.html#inp">inp</a></span></code> </td> |
| </tr> |
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| <code><a href="../../../../../../org/apache/hawq/pxf/api/utilities/Plugin.html#inputData">inputData</a></code></li> |
| </ul> |
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| <tr> |
| <th class="colOne" scope="col">Constructor and Description</th> |
| </tr> |
| <tr class="altColor"> |
| <td class="colOne"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/HdfsAtomicDataAccessor.html#HdfsAtomicDataAccessor-org.apache.hawq.pxf.api.utilities.InputData-">HdfsAtomicDataAccessor</a></span>(<a href="../../../../../../org/apache/hawq/pxf/api/utilities/InputData.html" title="class in org.apache.hawq.pxf.api.utilities">InputData</a> input)</code> |
| <div class="block">Constructs a HdfsAtomicDataAccessor object.</div> |
| </td> |
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| <th class="colLast" scope="col">Method and Description</th> |
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| <tr id="i0" class="altColor"> |
| <td class="colFirst"><code>void</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/HdfsAtomicDataAccessor.html#closeForRead--">closeForRead</a></span>()</code> |
| <div class="block">Closes the access stream when finished reading the file</div> |
| </td> |
| </tr> |
| <tr id="i1" class="rowColor"> |
| <td class="colFirst"><code>boolean</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/HdfsAtomicDataAccessor.html#isThreadSafe--">isThreadSafe</a></span>()</code> |
| <div class="block">Checks if the plugin is thread safe or not, based on inputData.</div> |
| </td> |
| </tr> |
| <tr id="i2" class="altColor"> |
| <td class="colFirst"><code>boolean</code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/HdfsAtomicDataAccessor.html#openForRead--">openForRead</a></span>()</code> |
| <div class="block">Opens the file using the non-splittable API for HADOOP HDFS file access |
| This means that instead of using a FileInputFormat for access, we use a |
| Java stream.</div> |
| </td> |
| </tr> |
| <tr id="i3" class="rowColor"> |
| <td class="colFirst"><code><a href="../../../../../../org/apache/hawq/pxf/api/OneRow.html" title="class in org.apache.hawq.pxf.api">OneRow</a></code></td> |
| <td class="colLast"><code><span class="memberNameLink"><a href="../../../../../../org/apache/hawq/pxf/plugins/hdfs/HdfsAtomicDataAccessor.html#readNextObject--">readNextObject</a></span>()</code> |
| <div class="block">Fetches one record from the file.</div> |
| </td> |
| </tr> |
| </table> |
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| <h3>Methods inherited from class java.lang.Object</h3> |
| <code>clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait</code></li> |
| </ul> |
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| <a name="inp"> |
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| <h4>inp</h4> |
| <pre>protected java.io.InputStream inp</pre> |
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| <h4>HdfsAtomicDataAccessor</h4> |
| <pre>public HdfsAtomicDataAccessor(<a href="../../../../../../org/apache/hawq/pxf/api/utilities/InputData.html" title="class in org.apache.hawq.pxf.api.utilities">InputData</a> input)</pre> |
| <div class="block">Constructs a HdfsAtomicDataAccessor object.</div> |
| <dl> |
| <dt><span class="paramLabel">Parameters:</span></dt> |
| <dd><code>input</code> - all input parameters coming from the client</dd> |
| </dl> |
| </li> |
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| <a name="openForRead--"> |
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| <h4>openForRead</h4> |
| <pre>public boolean openForRead() |
| throws java.lang.Exception</pre> |
| <div class="block">Opens the file using the non-splittable API for HADOOP HDFS file access |
| This means that instead of using a FileInputFormat for access, we use a |
| Java stream.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="../../../../../../org/apache/hawq/pxf/api/ReadAccessor.html#openForRead--">openForRead</a></code> in interface <code><a href="../../../../../../org/apache/hawq/pxf/api/ReadAccessor.html" title="interface in org.apache.hawq.pxf.api">ReadAccessor</a></code></dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>true for successful file open, false otherwise</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.lang.Exception</code> - if opening the resource failed</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="readNextObject--"> |
| <!-- --> |
| </a> |
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| <h4>readNextObject</h4> |
| <pre>public <a href="../../../../../../org/apache/hawq/pxf/api/OneRow.html" title="class in org.apache.hawq.pxf.api">OneRow</a> readNextObject() |
| throws java.io.IOException</pre> |
| <div class="block">Fetches one record from the file.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="../../../../../../org/apache/hawq/pxf/api/ReadAccessor.html#readNextObject--">readNextObject</a></code> in interface <code><a href="../../../../../../org/apache/hawq/pxf/api/ReadAccessor.html" title="interface in org.apache.hawq.pxf.api">ReadAccessor</a></code></dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>a <a href="../../../../../../org/apache/hawq/pxf/api/OneRow.html" title="class in org.apache.hawq.pxf.api"><code>OneRow</code></a> record as a Java object. Returns null if none.</dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.io.IOException</code></dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="closeForRead--"> |
| <!-- --> |
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| <h4>closeForRead</h4> |
| <pre>public void closeForRead() |
| throws java.lang.Exception</pre> |
| <div class="block">Closes the access stream when finished reading the file</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Specified by:</span></dt> |
| <dd><code><a href="../../../../../../org/apache/hawq/pxf/api/ReadAccessor.html#closeForRead--">closeForRead</a></code> in interface <code><a href="../../../../../../org/apache/hawq/pxf/api/ReadAccessor.html" title="interface in org.apache.hawq.pxf.api">ReadAccessor</a></code></dd> |
| <dt><span class="throwsLabel">Throws:</span></dt> |
| <dd><code>java.lang.Exception</code> - if closing the resource failed</dd> |
| </dl> |
| </li> |
| </ul> |
| <a name="isThreadSafe--"> |
| <!-- --> |
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| <li class="blockList"> |
| <h4>isThreadSafe</h4> |
| <pre>public boolean isThreadSafe()</pre> |
| <div class="block"><span class="descfrmTypeLabel">Description copied from class: <code><a href="../../../../../../org/apache/hawq/pxf/api/utilities/Plugin.html#isThreadSafe--">Plugin</a></code></span></div> |
| <div class="block">Checks if the plugin is thread safe or not, based on inputData.</div> |
| <dl> |
| <dt><span class="overrideSpecifyLabel">Overrides:</span></dt> |
| <dd><code><a href="../../../../../../org/apache/hawq/pxf/api/utilities/Plugin.html#isThreadSafe--">isThreadSafe</a></code> in class <code><a href="../../../../../../org/apache/hawq/pxf/api/utilities/Plugin.html" title="class in org.apache.hawq.pxf.api.utilities">Plugin</a></code></dd> |
| <dt><span class="returnLabel">Returns:</span></dt> |
| <dd>true if plugin is thread safe</dd> |
| </dl> |
| </li> |
| </ul> |
| </li> |
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