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157 lines
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<h1 id="lob-objects"><span id="lobobj"></span>LOB Objects<a class="headerlink" href="#lob-objects" title="Permalink to this headline">¶</a></h1>
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<div class="admonition note">
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<p class="first admonition-title">Note</p>
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<p class="last">This object is an extension the DB API. It is returned whenever Oracle
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<tt class="xref docutils literal"><span class="pre">CLOB</span></tt>, <tt class="xref docutils literal"><span class="pre">BLOB</span></tt> and <tt class="xref docutils literal"><span class="pre">BFILE</span></tt> columns are fetched.</p>
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<div class="admonition note">
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<p class="first admonition-title">Note</p>
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<p class="last">Internally, Oracle uses LOB locators which are allocated based on the
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cursor array size. Thus, it is important that the data in the LOB object be
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manipulated before another internal fetch takes place. The safest way to do
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this is to use the cursor as an iterator. In particular, do not use the
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fetchall() method. The exception “LOB variable no longer valid after
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subsequent fetch” will be raised if an attempt to access a LOB variable
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after a subsequent fetch is detected.</p>
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</div>
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<dl class="method">
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<dt id="LOB.close">
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<!--#LOB.close#--><tt class="descclassname">LOB.</tt><tt class="descname">close</tt><big>(</big><big>)</big><a class="headerlink" href="#LOB.close" title="Permalink to this definition">¶</a></dt>
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<dd>Close the <tt class="xref docutils literal"><span class="pre">LOB</span></tt>. Call this when writing is completed so that the
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indexes associated with the LOB can be updated.</dd></dl>
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<dl class="method">
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<dt id="LOB.fileexists">
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<!--#LOB.fileexists#--><tt class="descclassname">LOB.</tt><tt class="descname">fileexists</tt><big>(</big><big>)</big><a class="headerlink" href="#LOB.fileexists" title="Permalink to this definition">¶</a></dt>
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<dd>Return a boolean indicating if the file referenced by the <tt class="xref docutils literal"><span class="pre">BFILE</span></tt>
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type LOB exists.</dd></dl>
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<dl class="method">
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<dt id="LOB.getchunksize">
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<!--#LOB.getchunksize#--><tt class="descclassname">LOB.</tt><tt class="descname">getchunksize</tt><big>(</big><big>)</big><a class="headerlink" href="#LOB.getchunksize" title="Permalink to this definition">¶</a></dt>
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<dd>Return the chunk size for the internal LOB. Reading and writing to the LOB
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in chunks of multiples of this size will improve performance.</dd></dl>
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<dl class="method">
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<dt id="LOB.getfilename">
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<!--#LOB.getfilename#--><tt class="descclassname">LOB.</tt><tt class="descname">getfilename</tt><big>(</big><big>)</big><a class="headerlink" href="#LOB.getfilename" title="Permalink to this definition">¶</a></dt>
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<dd>Return a two-tuple consisting of the directory alias and file name for a
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<tt class="xref docutils literal"><span class="pre">BFILE</span></tt> type LOB.</dd></dl>
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<dl class="method">
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<dt id="LOB.isopen">
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<!--#LOB.isopen#--><tt class="descclassname">LOB.</tt><tt class="descname">isopen</tt><big>(</big><big>)</big><a class="headerlink" href="#LOB.isopen" title="Permalink to this definition">¶</a></dt>
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<dd>Return a boolean indicating if the LOB is opened.</dd></dl>
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<dl class="method">
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<dt id="LOB.open">
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<!--#LOB.open#--><tt class="descclassname">LOB.</tt><tt class="descname">open</tt><big>(</big><big>)</big><a class="headerlink" href="#LOB.open" title="Permalink to this definition">¶</a></dt>
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<dd>Open the LOB for writing. This will improve performance when writing to a
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LOB in chunks and there are functional or extensible indexes associated with
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the LOB.</dd></dl>
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<dl class="method">
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<dt id="LOB.read">
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<!--#LOB.read#--><tt class="descclassname">LOB.</tt><tt class="descname">read</tt><big>(</big><span class="optional">[</span><em>offset=1</em><span class="optional">[</span>, <em>amount</em><span class="optional">]</span><span class="optional">]</span><big>)</big><a class="headerlink" href="#LOB.read" title="Permalink to this definition">¶</a></dt>
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<dd>Return a portion (or all) of the data in the LOB object.</dd></dl>
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<dl class="method">
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<dt id="LOB.setfilename">
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<!--#LOB.setfilename#--><tt class="descclassname">LOB.</tt><tt class="descname">setfilename</tt><big>(</big><em>dirAlias</em>, <em>name</em><big>)</big><a class="headerlink" href="#LOB.setfilename" title="Permalink to this definition">¶</a></dt>
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<dd>Set the directory alias and name of the <tt class="xref docutils literal"><span class="pre">BFILE</span></tt> type LOB.</dd></dl>
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<dl class="method">
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<dt id="LOB.size">
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<!--#LOB.size#--><tt class="descclassname">LOB.</tt><tt class="descname">size</tt><big>(</big><big>)</big><a class="headerlink" href="#LOB.size" title="Permalink to this definition">¶</a></dt>
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<dd>Returns the size of the data in the LOB object.</dd></dl>
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<dl class="method">
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<dt id="LOB.trim">
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<!--#LOB.trim#--><tt class="descclassname">LOB.</tt><tt class="descname">trim</tt><big>(</big><span class="optional">[</span><em>newSize=0</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#LOB.trim" title="Permalink to this definition">¶</a></dt>
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<dd>Trim the LOB to the new size.</dd></dl>
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<dl class="method">
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<dt id="LOB.write">
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<!--#LOB.write#--><tt class="descclassname">LOB.</tt><tt class="descname">write</tt><big>(</big><em>data</em><span class="optional">[</span>, <em>offset=1</em><span class="optional">]</span><big>)</big><a class="headerlink" href="#LOB.write" title="Permalink to this definition">¶</a></dt>
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<dd>Write the data to the LOB object at the given offset. Note that if you want
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to make the LOB value smaller, you must use the trim() function.</dd></dl>
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© Copyright 2008, Anthony Tuininga.
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Last updated on Dec 11, 2008.
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