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<title>psqlODBC HOWTO - Access Large Objects</title>
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<h1>psqlODBC HOWTO - Access Large Objects</h1>
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Release Date: Unknown<br>
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Description: Using large objects in Microsoft Access (notes from the original psqlODBC docs)
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<h2>Using Large Objects for handling LongVarBinary (OLE Objects in Access)</h2>
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<p>Large objects are mapped to LONGVARBINARY in the driver to allow storing things like
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OLE objects in Microsoft Access. Multiple SQLPutData and SQLGetData calls are usually
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used to send and retrieve these objects. The driver creates a new large object and simply
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inserts its 'identifier' into the respective table. However, since PostgreSQL uses an 'Oid'
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to identify a Large Object, it is necessary to create a new PostgreSQL type to be able
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to discriminate between an ordinary Oid and a Large Object Oid. Until this new type
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becomes an official part of PostgreSQL, it must be added into the desired database and
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looked up for each connection. The type used in the driver is simply called "lo" and
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here is the command used to create it:</p>
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<p>Once this is done, simply use the new 'lo' type to define columns in that database. Note
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that this must be done for each database you want to use large objects in with the driver.
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When the driver sees an 'lo' type, it will handle it as LONGVARBINARY.</p>
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<p>Another important note is that this new type is lacking in functionality. It will not
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cleanup after itself on updates and deletes, thus leaving orphans around and using up
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extra disk space. And currently, PostgreSQL does not support the vacuuming of large
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objects. Hopefully in the future, a real large object data type will be available.</p>
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<p>But for now, it sure is fun to stick a Word document, Visio document, or avi of a dancing
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baby into a database column, even if you will fill up your server's hard disk after a while!</p>
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