| <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> |
| <!-- NewPage --> |
| <html lang="en"> |
| <head> |
| <!-- Generated by javadoc --> |
| <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> |
| <title>org.apache.drill.exec.vector.accessor.writer.dummy (Drill : 1.20.3 API)</title> |
| <link rel="stylesheet" type="text/css" href="../../../../../../../../stylesheet.css" title="Style"> |
| <script type="text/javascript" src="../../../../../../../../script.js"></script> |
| </head> |
| <body> |
| <script type="text/javascript"><!-- |
| try { |
| if (location.href.indexOf('is-external=true') == -1) { |
| parent.document.title="org.apache.drill.exec.vector.accessor.writer.dummy (Drill : 1.20.3 API)"; |
| } |
| } |
| catch(err) { |
| } |
| //--> |
| </script> |
| <noscript> |
| <div>JavaScript is disabled on your browser.</div> |
| </noscript> |
| <!-- ========= START OF TOP NAVBAR ======= --> |
| <div class="topNav"><a name="navbar.top"> |
| <!-- --> |
| </a> |
| <div class="skipNav"><a href="#skip.navbar.top" title="Skip navigation links">Skip navigation links</a></div> |
| <a name="navbar.top.firstrow"> |
| <!-- --> |
| </a> |
| <ul class="navList" title="Navigation"> |
| <li><a href="../../../../../../../../overview-summary.html">Overview</a></li> |
| <li class="navBarCell1Rev">Package</li> |
| <li>Class</li> |
| <li><a href="package-use.html">Use</a></li> |
| <li><a href="package-tree.html">Tree</a></li> |
| <li><a href="../../../../../../../../deprecated-list.html">Deprecated</a></li> |
| <li><a href="../../../../../../../../index-all.html">Index</a></li> |
| <li><a href="../../../../../../../../help-doc.html">Help</a></li> |
| </ul> |
| </div> |
| <div class="subNav"> |
| <ul class="navList"> |
| <li><a href="../../../../../../../../org/apache/drill/exec/vector/accessor/writer/package-summary.html">Prev Package</a></li> |
| <li><a href="../../../../../../../../org/apache/drill/exec/vector/complex/package-summary.html">Next Package</a></li> |
| </ul> |
| <ul class="navList"> |
| <li><a href="../../../../../../../../index.html?org/apache/drill/exec/vector/accessor/writer/dummy/package-summary.html" target="_top">Frames</a></li> |
| <li><a href="package-summary.html" target="_top">No Frames</a></li> |
| </ul> |
| <ul class="navList" id="allclasses_navbar_top"> |
| <li><a href="../../../../../../../../allclasses-noframe.html">All Classes</a></li> |
| </ul> |
| <div> |
| <script type="text/javascript"><!-- |
| allClassesLink = document.getElementById("allclasses_navbar_top"); |
| if(window==top) { |
| allClassesLink.style.display = "block"; |
| } |
| else { |
| allClassesLink.style.display = "none"; |
| } |
| //--> |
| </script> |
| </div> |
| <a name="skip.navbar.top"> |
| <!-- --> |
| </a></div> |
| <!-- ========= END OF TOP NAVBAR ========= --> |
| <div class="header"> |
| <h1 title="Package" class="title">Package org.apache.drill.exec.vector.accessor.writer.dummy</h1> |
| <div class="docSummary"> |
| <div class="block">This package provides a "dummy" set of writers.</div> |
| </div> |
| <p>See: <a href="#package.description">Description</a></p> |
| </div> |
| <div class="contentContainer"> |
| <ul class="blockList"> |
| <li class="blockList"> |
| <table class="typeSummary" border="0" cellpadding="3" cellspacing="0" summary="Class Summary table, listing classes, and an explanation"> |
| <caption><span>Class Summary</span><span class="tabEnd"> </span></caption> |
| <tr> |
| <th class="colFirst" scope="col">Class</th> |
| <th class="colLast" scope="col">Description</th> |
| </tr> |
| <tbody> |
| <tr class="altColor"> |
| <td class="colFirst"><a href="../../../../../../../../org/apache/drill/exec/vector/accessor/writer/dummy/DummyArrayWriter.html" title="class in org.apache.drill.exec.vector.accessor.writer.dummy">DummyArrayWriter</a></td> |
| <td class="colLast"> |
| <div class="block">Dummy scalar array writer that allows a client to write values into |
| the array, but discards all of them.</div> |
| </td> |
| </tr> |
| <tr class="rowColor"> |
| <td class="colFirst"><a href="../../../../../../../../org/apache/drill/exec/vector/accessor/writer/dummy/DummyArrayWriter.DummyOffsetVectorWriter.html" title="class in org.apache.drill.exec.vector.accessor.writer.dummy">DummyArrayWriter.DummyOffsetVectorWriter</a></td> |
| <td class="colLast"> </td> |
| </tr> |
| <tr class="altColor"> |
| <td class="colFirst"><a href="../../../../../../../../org/apache/drill/exec/vector/accessor/writer/dummy/DummyDictWriter.html" title="class in org.apache.drill.exec.vector.accessor.writer.dummy">DummyDictWriter</a></td> |
| <td class="colLast"> </td> |
| </tr> |
| <tr class="rowColor"> |
| <td class="colFirst"><a href="../../../../../../../../org/apache/drill/exec/vector/accessor/writer/dummy/DummyScalarWriter.html" title="class in org.apache.drill.exec.vector.accessor.writer.dummy">DummyScalarWriter</a></td> |
| <td class="colLast"> |
| <div class="block">Represents a non-projected column.</div> |
| </td> |
| </tr> |
| </tbody> |
| </table> |
| </li> |
| </ul> |
| <a name="package.description"> |
| <!-- --> |
| </a> |
| <h2 title="Package org.apache.drill.exec.vector.accessor.writer.dummy Description">Package org.apache.drill.exec.vector.accessor.writer.dummy Description</h2> |
| <div class="block">This package provides a "dummy" set of writers. The dummy writers provide |
| the same API as the "real" writers, but the dummy writers simply discard |
| their data. The dummy writers are used when implementing projection: |
| non-projected columns may still have to be processed (as in a CSV file, |
| say), but their values are not needed. One way to do this is to do an |
| if-statement for each value:<pre><code> |
| if (column-a-is-projected) { |
| aWriter.setSomething(value); |
| }</code></pre> |
| The dummy writers convert the if-statement into a virtual function call, |
| same as is done to handle the type-specific nature of vectors: |
| <pre><code> |
| aWriter.setSomething(value); |
| </code></pre> |
| <p> |
| The theory is that the virtual function dispatch is simpler, and faster, |
| than doing continual if-checks everywhere in the code. |
| <p> |
| The dummy writers reside in this package so that the various factory |
| methods can automatically build the dummy versions when given a null |
| value vector (which we then interpret to mean that there is no physical |
| backing to the column.) |
| <p> |
| At present, most methods that return a value simply return zero or |
| null. |
| Experience will show whether it is worthwhile implementing some |
| basics, such as a value type or index. For now, these return null, |
| assuming that the caller won't do anything with the column other |
| than set a value. |
| <p> |
| Some simpler dummy writers appear as nested classes inside the |
| "real" writers.</div> |
| </div> |
| <!-- ======= START OF BOTTOM NAVBAR ====== --> |
| <div class="bottomNav"><a name="navbar.bottom"> |
| <!-- --> |
| </a> |
| <div class="skipNav"><a href="#skip.navbar.bottom" title="Skip navigation links">Skip navigation links</a></div> |
| <a name="navbar.bottom.firstrow"> |
| <!-- --> |
| </a> |
| <ul class="navList" title="Navigation"> |
| <li><a href="../../../../../../../../overview-summary.html">Overview</a></li> |
| <li class="navBarCell1Rev">Package</li> |
| <li>Class</li> |
| <li><a href="package-use.html">Use</a></li> |
| <li><a href="package-tree.html">Tree</a></li> |
| <li><a href="../../../../../../../../deprecated-list.html">Deprecated</a></li> |
| <li><a href="../../../../../../../../index-all.html">Index</a></li> |
| <li><a href="../../../../../../../../help-doc.html">Help</a></li> |
| </ul> |
| </div> |
| <div class="subNav"> |
| <ul class="navList"> |
| <li><a href="../../../../../../../../org/apache/drill/exec/vector/accessor/writer/package-summary.html">Prev Package</a></li> |
| <li><a href="../../../../../../../../org/apache/drill/exec/vector/complex/package-summary.html">Next Package</a></li> |
| </ul> |
| <ul class="navList"> |
| <li><a href="../../../../../../../../index.html?org/apache/drill/exec/vector/accessor/writer/dummy/package-summary.html" target="_top">Frames</a></li> |
| <li><a href="package-summary.html" target="_top">No Frames</a></li> |
| </ul> |
| <ul class="navList" id="allclasses_navbar_bottom"> |
| <li><a href="../../../../../../../../allclasses-noframe.html">All Classes</a></li> |
| </ul> |
| <div> |
| <script type="text/javascript"><!-- |
| allClassesLink = document.getElementById("allclasses_navbar_bottom"); |
| if(window==top) { |
| allClassesLink.style.display = "block"; |
| } |
| else { |
| allClassesLink.style.display = "none"; |
| } |
| //--> |
| </script> |
| </div> |
| <a name="skip.navbar.bottom"> |
| <!-- --> |
| </a></div> |
| <!-- ======== END OF BOTTOM NAVBAR ======= --> |
| <p class="legalCopy"><small>Copyright © 1970 <a href="https://www.apache.org/">The Apache Software Foundation</a>. All rights reserved.</small></p> |
| </body> |
| </html> |
