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| <meta name="DC.Title" content="Querying Heap Objects (OQL)"/> |
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| <h1 class="title topictitle1">Querying Heap Objects (OQL)</h1> |
| |
| |
| |
| <div class="body taskbody"> |
| <div class="section context"> |
| <p class="p">Memory Analyzer allows to query the heap dump with custom |
| SQL-like queries. OQL represents classes as tables, objects as rows, |
| and fields as columns.</p> |
| |
| <pre class="pre codeblock">SELECT * |
| FROM [ INSTANCEOF ] <class name="name"> |
| [ WHERE <filter-expression> ] |
| </filter-expression></class></pre> |
| |
| <p class="p">To open an OQL editor use the toolbar button <img class="image" src="../mimes/i-oqleditor.png" alt="open object query language button"/>:</p> |
| |
| <p class="p">OQL editor is divided into two areas:</p> |
| |
| <ul class="ul"><li class="li">Text area to type in the query (upper area)</li> |
| |
| <li class="li">Result area to display the result of the query execution</li> |
| </ul> |
| |
| <img class="image" src="../mimes/m2fd32fba.png" alt="screen shot of query result"/> |
| <p class="p">Use F5 or Ctrl-Enter or toolbar button <img class="image" src="../mimes/4fd3f07a.png" alt="Execute Query button"/> to execute the query.</p> |
| |
| <p class="p">Basic OQL syntax is as follows:</p> |
| |
| <pre class="pre codeblock"> |
| SELECT * |
| FROM [ INSTANCEOF ] <class name> |
| [ WHERE <filter-expression> ] |
| </pre> |
| |
| <p class="p"> |
| The text area has autocompletion for class names, class name regular expressions, |
| field names, attributes and methods. |
| See <a class="xref" href="../reference/tipsandtricks.html#oqlcompletion">OQL autocompletion</a>. |
| </p> |
| |
| <p class="p"> |
| The navigation history shows previous OQL queries. Clicking on a previous query |
| executes it again. On many result panes, selecting some objects, then |
| <span class="ph menucascade"><span class="ph uicontrol">Copy</span> > <span class="ph uicontrol">OQL Query</span></span> |
| copies an OQL representation of the objects. This OQL can then be pasted |
| into the OQL editor text area. |
| This works from the OQL result area itself, and also copies the column details as well as the objects. |
| <img class="image" src="../mimes/oqlsaveresult.png" alt="screen shot of OQL navigation and copy OQL query"/> |
| </p> |
| |
| </div> |
| |
| </div> |
| |
| <div class="related-links"><div class="relinfo relref"><strong>Related reference</strong><br/> |
| <div><a class="link" href="../reference/oqlsyntax.html">OQL Syntax</a></div> |
| </div> |
| </div> |
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