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| <h1 class="title topictitle1" id="ariaid-title1">Querying Heap Objects (OQL)</h1> |
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| <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"><code>SELECT * |
| FROM [ INSTANCEOF ] <class name="name"> |
| [ WHERE <filter-expression> ] |
| </filter-expression></class></code></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 <span class="ph uicontrol">F5</span> or <span class="ph uicontrol">ctrl+enter</span> 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"><code> |
| SELECT * |
| FROM [ INSTANCEOF ] <class name> |
| [ WHERE <filter-expression> ] |
| </code></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><abbr title="and then"> > </abbr><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> |
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| </div> |
| |
| <div class="related-links"> |
| <div class="linklist relinfo relref" xml:lang="en-us" lang="en-us"><strong>Related reference</strong><br /> |
| <ul class="linklist"> |
| <li class="linklist"><a class="link" href="../reference/oqlsyntax.html">OQL Syntax</a></li></ul></div> |
| </div> |
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