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docs/documentation/92/ext.md

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+---
+layout: default_docs
+title: Chapter 9. PostgreSQL™ Extensions to the JDBC API
+header: Chapter 9. PostgreSQL™ Extensions to the JDBC API
+resource: media
+previoustitle: Escaped scalar functions
+previous: escaped-functions.html
+nexttitle: Geometric Data Types
+next: geometric.html
+---
+
+**Table of Contents**
+
+* [Accessing the Extensions](ext.html#extensions)
+* [Geometric Data Types](geometric.html)
+* [Large Objects](largeobjects.html)
+* [Listen / Notify](listennotify.html)
+* [Server Prepared Statements](server-prepare.html)
+
+PostgreSQL™ is an extensible database system. You can add your own functions to
+the server, which can then be called from queries, or even add your own data types.
+As these are facilities unique to PostgreSQL™, we support them from Java, with a
+set of extension APIs. Some features within the core of the standard driver
+actually use these extensions to implement Large Objects, etc.
+
+<a name="extensions"></a>
+# Accessing the Extensions
+
+To access some of the extensions, you need to use some extra methods in the
+`org.postgresql.PGConnection` class. In this case, you would need to case the
+return value of `Driver.getConnection()`. For example:
+
+`Connection db = Driver.getConnection(url, username, password);`  
+`// ...`  
+`// later on`  
+`Fastpath fp = db.unwrap(org.postgresql.PGConnection.class).getFastpathAPI();`