44 lines
2.0 KiB
Markdown
44 lines
2.0 KiB
Markdown
---
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layout: default_docs
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title: Chapter 11. Connection Pools and Data Sources
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header: Chapter 11. Connection Pools and Data Sources
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resource: media
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previoustitle: Chapter 10. Using the Driver in a Multithreaded or a Servlet Environment
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previous: thread.html
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nexttitle: Application Servers ConnectionPoolDataSource
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next: ds-cpds.html
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---
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**Table of Contents**
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* [Overview](datasource.html#ds-intro)
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* [Application Servers: `ConnectionPoolDataSource`](ds-cpds.html)
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* [Applications: `DataSource`](ds-ds.html)
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* [Tomcat setup](tomcat.html)
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* [Data Sources and JNDI](jndi.html)
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JDBC 2 introduced standard connection pooling features in an add-on API known as
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the JDBC 2.0 Optional Package (also known as the JDBC 2.0 Standard Extension).
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These features have since been included in the core JDBC 3 API.
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<a name="ds-intro"></a>
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# Overview
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The JDBC API provides a client and a server interface for connection pooling.
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The client interface is `javax.sql.DataSource`, which is what application code
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will typically use to acquire a pooled database connection. The server interface
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is `javax.sql.ConnectionPoolDataSource`, which is how most application servers
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will interface with the PostgreSQL™ JDBC driver.
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In an application server environment, the application server configuration will
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typically refer to the PostgreSQL™ `ConnectionPoolDataSource` implementation,
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while the application component code will typically acquire a `DataSource`
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implementation provided by the application server (not by PostgreSQL™).
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For an environment without an application server, PostgreSQL™ provides two
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implementations of `DataSource` which an application can use directly. One
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implementation performs connection pooling, while the other simply provides
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access to database connections through the `DataSource` interface without any
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pooling. Again, these implementations should not be used in an application server
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environment unless the application server does not support the `ConnectionPoolDataSource`
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interface. |