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<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="sect1" lang="en">
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<a name="catalog-pg-largeobject"></a>41.19.�<tt class="structname">pg_largeobject</tt></h2></div></div>
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<a name="id2726158"></a><p> The catalog <tt class="structname">pg_largeobject</tt> holds the data making up
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“<span class="quote">large objects</span>”. A large object is identified by an
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OID assigned when it is created. Each large object is broken into
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segments or “<span class="quote">pages</span>” small enough to be conveniently stored as rows
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in <tt class="structname">pg_largeobject</tt>.
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The amount of data per page is defined to be <tt class="literal">LOBLKSIZE</tt> (which is currently
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<tt class="literal">BLCKSZ/4</tt>, or typically 2 kB).
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<a name="id2726202"></a><p class="title"><b>Table�41.19.�<tt class="structname">pg_largeobject</tt> Columns</b></p>
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<table summary="pg_largeobject Columns" border="1">
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<td><tt class="structfield">loid</tt></td>
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<td><tt class="type">oid</tt></td>
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<td>Identifier of the large object that includes this page</td>
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<td><tt class="structfield">pageno</tt></td>
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<td><tt class="type">int4</tt></td>
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<td>Page number of this page within its large object
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(counting from zero)</td>
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<td><tt class="structfield">data</tt></td>
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<td><tt class="type">bytea</tt></td>
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<td> Actual data stored in the large object.
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This will never be more than <tt class="symbol">LOBLKSIZE</tt> bytes and may be less.
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<p> Each row of <tt class="structname">pg_largeobject</tt> holds data
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for one page of a large object, beginning at
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byte offset (<tt class="literal">pageno * LOBLKSIZE</tt>) within the object. The implementation
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allows sparse storage: pages may be missing, and may be shorter than
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<tt class="literal">LOBLKSIZE</tt> bytes even if they are not the last page of the object.
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Missing regions within a large object read as zeroes.
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docs/en_US/pg/catalog-pg-largeobject.html
