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| <h1 class="title topictitle1" id="ariaid-title1">FROM Clause</h1> |
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| <div class="body refbody"><p class="shortdesc"></p> |
| |
| <div class="section"><h2 class="title sectiontitle">Specify the class</h2> |
| |
| <p class="p"> |
| The <code class="ph codeph">FROM</code> clause defines the classes on which to operate. |
| Specify the class by one of the following means: |
| </p> |
| |
| <strong class="ph b">by class name:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM java.lang.String</code></pre> |
| <strong class="ph b">by a regular expression matching the class name:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM "java\.lang\..*"</code></pre> |
| <strong class="ph b">by the object address of the class:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM 0x2b7468c8</code></pre> |
| <strong class="ph b">by the object addresses of more than one class:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM 0x2b7468c8,0x2b74aee0</code></pre> |
| <strong class="ph b">by the object id of the class:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM 20815</code></pre> |
| <strong class="ph b">by the object ids of more than one class:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM 20815,20975</code></pre> |
| <strong class="ph b">by a sub select:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM ( SELECT * |
| FROM java.lang.Class c |
| WHERE c implements org.eclipse.mat.snapshot.model.IClass )</code></pre> |
| <p class="p"> |
| The statement returns all objects in the heap. The |
| <code class="ph codeph">implements</code> |
| check is necessary, as the heap dump can contain |
| <code class="ph codeph">java.lang.Class</code> |
| instances caused by proxy classes or classes representing |
| primitive types such as |
| <code class="ph codeph">int.class</code> or <code class="ph codeph">Integer.TYPE</code>. |
| The following query has |
| the same effect, which calls a method directly on |
| the ISnapshot object: |
| </p> |
| |
| <pre class="pre codeblock"><code>SELECT * FROM ${snapshot}.getClasses()</code></pre> |
| </div> |
| |
| <div class="section"><h2 class="title sectiontitle">Include sub classes</h2> |
| |
| <p class="p"> |
| Use the |
| <code class="ph codeph">INSTANCEOF</code> |
| keyword to include objects of sub-classes into the |
| query: |
| </p> |
| |
| <pre class="pre codeblock"><code>SELECT * FROM INSTANCEOF java.lang.ref.Reference</code></pre> |
| <p class="p"> |
| The resulting table contains, amongst others, |
| WeakReference and SoftReference objects because both |
| classes extend from |
| <code class="ph codeph">java.lang.ref.Reference</code> |
| . By the way, the same result has the following query |
| </p> |
| |
| <pre class="pre codeblock"><code>SELECT * FROM ${snapshot}.getClassesByName("java.lang.ref.Reference", true)</code></pre> |
| </div> |
| |
| <div class="section"><h2 class="title sectiontitle"> |
| Prevent interpretation of the from term as classes |
| </h2> |
| |
| <p class="p"> |
| Use the OBJECTS keyword if you do not want to process |
| the term as classes. |
| Specify the object or objects by one of the following means: |
| </p> |
| |
| <strong class="ph b">by class name:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM OBJECTS java.lang.String</code></pre> |
| <p class="p"> |
| The result is just one object, the java.lang.String |
| class object. |
| </p> |
| |
| <strong class="ph b">by the object address of the particular object:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM OBJECTS 0x2b7468c8</code></pre> |
| <strong class="ph b">by the object addresses of particular objects:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM OBJECTS 0x2b7468c8,0x2b746868</code></pre> |
| <strong class="ph b">by the object id of the particular object:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM OBJECTS 20815</code></pre> |
| <strong class="ph b">by the object ids of particular objects:</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM OBJECTS 20815,20814</code></pre> |
| <strong class="ph b">by a sub expression (Memory Analyzer 1.4 or later):</strong> |
| <pre class="pre codeblock"><code>SELECT * FROM OBJECTS (1 + ${snapshot}.GCRoots.length)</code></pre> |
| <strong class="ph b">by a sub select returning an object list</strong> |
| <pre class="pre codeblock"><code>SELECT v, v.@length FROM OBJECTS ( SELECT OBJECTS s.value FROM java.lang.String s ) v</code></pre> |
| <strong class="ph b">In Memory Analyzer 1.10 and later, sub-selects are now also permitted which have select items.</strong> |
| <pre class="pre codeblock"><code>SELECT v,v.s,v.val FROM OBJECTS ( SELECT s,s.value as val FROM java.lang.String s ) v</code></pre> |
| See <a class="xref" href="https://wiki.eclipse.org/MemoryAnalyzer/OQL#Sub_SELECT_with_select_items">Wiki Sub select with select items</a> |
| for more details. |
| <div class="note"><span class="notetitle">Note:</span> |
| Please note, that currently the <code class="ph codeph">FROM OBJECTS</code> term is in |
| the test phase! |
| </div> |
| |
| </div> |
| |
| <div class="section" id="ref_oqlsyntaxfrom__unindexed"><h2 class="title sectiontitle"> |
| Unindexed objects |
| </h2> |
| |
| <div class="p"> |
| Normally heap objects are indexed in the snapshot and are referred to |
| by an object id, not an address. |
| If objects have been discarded from the snapshot during parsing, |
| either because they are unreachable, or because of the discard option |
| then sometimes they can still be accessed in OQL. |
| If you know the object address, then a query such as |
| <pre class="pre codeblock"><code>SELECT * FROM OBJECTS 0x2b7468c8</code></pre> |
| will retrieve it. |
| The result of the query is different however. Instead of the |
| object being processed as an object id and displayed in a |
| list objects query tree view, it is returned as part of a list |
| of IObject and is displayed as a table view. |
| </div> |
| |
| <div class="p">Unindexed objects will not be returned as a result of |
| <ul class="ul"> |
| <li class="li"><code class="ph codeph">outbound()</code> |
| </li> |
| |
| <li class="li"><code class="ph codeph">inbound()</code> |
| </li> |
| |
| <li class="li"><code class="ph codeph">dominators()</code> |
| </li> |
| |
| <li class="li"><code class="ph codeph">dominatorof()</code> |
| </li> |
| |
| </ul> |
| |
| and will cause an error if supplied as an argument to those |
| functions. |
| The built-in function <code class="ph codeph">classof()</code> does work |
| with unindexed objects. |
| </div> |
| |
| <p class="p">See how unindexed objects appear in the inspector view when |
| retrieved by OQL. Note the |
| <img class="image" src="../mimes/message_warning.png" alt="yellow warning triangle icon" /> |
| warning triangle and the <samp class="ph msgph">Unindexed</samp> |
| in the inspector view top panel, and the <samp class="ph msgph">Unindexed</samp> suffix |
| in the object view. The retained size is 0 as the retained size is not |
| calculated for unindexed objects. |
| <img class="image" src="../mimes/inspector_unindexed.png" height="682" width="1267" alt="Inspector View with unindexed object"" /> |
| </p> |
| |
| <div class="note"><span class="notetitle">Note:</span> |
| Please note, that currently the unindexed objects facility is in |
| the test phase! |
| </div> |
| |
| </div> |
| |
| <div class="section"><h2 class="title sectiontitle"> |
| Autocompletion |
| </h2> |
| |
| <p class="p"> |
| The OQL pane now has autocompletion for class names, class name regular expressions, |
| field names, attributes and methods. |
| See <a class="xref" href="tipsandtricks.html#oqlcompletion">OQL autocompletion</a>. |
| </p> |
| |
| </div> |
| |
| </div> |
| |
| <div class="related-links"> |
| <div class="familylinks"> |
| <div class="parentlink"><strong>Parent topic:</strong> <a class="link" href="../reference/oqlsyntax.html">OQL Syntax</a></div> |
| </div> |
| </div></body> |
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