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Natively Connect to HDFS Data in PHP

The CData ODBC driver for HDFS enables you to create PHP applications with connectivity to HDFS data. Leverage the native support for ODBC in PHP.

Drop the CData ODBC Driver for HDFS into your LAMP or WAMP stack to build HDFS-connected Web applications. This article shows how to use PHP's ODBC built-in functions to connect to HDFS data, execute queries, and output the results.

Configure a DSN

If you have not already, first specify connection properties in an ODBC DSN (data source name). This is the last step of the driver installation. You can use the Microsoft ODBC Data Source Administrator to create and configure ODBC DSNs.

In order to authenticate, set the following connection properties:

  • Host: Set this value to the host of your HDFS installation.
  • Port: Set this value to the port of your HDFS installation. Default port: 50070

Establish a Connection

Open the connection to HDFS by calling the odbc_connect or odbc_pconnect methods. To close connections, use odbc_close or odbc_close_all.

$conn = odbc_connect("CData ODBC HDFS Source","user","password");

Connections opened with odbc_connect are closed when the script ends. Connections opened with the odbc_pconnect method are still open after the script ends. This enables other scripts to share that connection when they connect with the same credentials. By sharing connections among your scripts, you can save system resources, and queries execute faster.

$conn = odbc_pconnect("CData ODBC HDFS Source","user","password"); ... odbc_close($conn); //persistent connection must be closed explicitly

Create Prepared Statements

Create prepared statements and parameterized queries with the odbc_prepare function.

$query = odbc_prepare($conn, "SELECT * FROM Files WHERE FileId = ?");

Execute Queries

Execute prepared statements with odbc_execute.

$conn = odbc_connect("CData ODBC HDFS Source","user","password"); $query = odbc_prepare($conn, "SELECT * FROM Files WHERE FileId = ?"); $success = odbc_execute($query, array('119116'));

Execute nonparameterized queries with odbc_exec.

$conn = odbc_connect("CData ODBC HDFS Source","user","password"); $query = odbc_exec($conn, "SELECT FileId, ChildrenNum FROM Files WHERE FileId = '119116'");

Process Results

Access a row in the result set as an array with the odbc_fetch_array function.

$conn = odbc_connect("CData ODBC HDFS data Source","user","password"); $query = odbc_exec($conn, "SELECT FileId, ChildrenNum FROM Files WHERE FileId = '119116'"); while($row = odbc_fetch_array($query)){ echo $row["FileId"] . "\n"; }

Display the result set in an HTML table with the odbc_result_all function.

$conn = odbc_connect("CData ODBC HDFS data Source","user","password"); $query = odbc_prepare($conn, "SELECT * FROM Files WHERE FileId = ?"); $success = odbc_execute($query, array('119116')); if($success) odbc_result_all($query);

More Example Queries

You will find complete information on the driver's supported SQL in the help documentation. The code examples above are HDFS-specific adaptations of the PHP community documentation for all ODBC functions.