Datastax Cassandra PHP 驱动程序

Posted 2023-03-22

【中文标题】Datastax Cassandra PHP 驱动程序

【英文标题】：Datastax Cassandra PHP Driver

【发布时间】：2016-02-27 05:16:51

【问题描述】：

我正在使用适用于 php 的 Datastax Cassandra 驱动程序，并希望能够检查查询是否失败，是否在数据库中找不到结果。现在，如果查询失败，日志会报告以下内容

PHP Fatal error:  Uncaught exception 'Cassandra\\Exception\\RuntimeException' with message 'No hosts available for the control connection' in /var/www/html/includes/conditions.php:153\nStack trace:\n#0 /var/www/html/includes/conditions.php(153): Cassandra\\DefaultCluster->connect('loop_non_hadoop')\n#1 /var/www/html/index.php(159): check_key('0x851702c16d824...')\n#2 main\n  thrown in /var/www/html/includes/conditions.php on line 153, referer: http://172.29.195.10:5050/html/index.php

如果查询成功，它将按预期返回数据。这是函数

function check_key($key)
    $cluster = Cassandra::cluster()->build();
    //set this to the appropriate keyspace
    $keyspace = 'loop_non_hadoop'; 
    $session = $cluster->connect($keyspace);
    $query = "SELECT * FROM events WHERE key=$key";
    $statement = new Cassandra\SimpleStatement($query);

    $results = $session->execute($statement);

    if(empty($results))
        return;
    
    else 
        foreach ($results as $row) 
            echo "<tr id='cell'><td>Title</td><td>" . $row['title'] . "</td></tr>";
            echo "<tr><td>Location</td><td>" . $row['locationName'] . "</td></tr>";
            echo "<tr id='cell'><td>City</td><td>" . $row['city'] . "</td></tr>";
            echo "<tr><td>State</td><td>" . $row['state'] . "</td></tr>";
            echo "<tr id='cell'><td>Zip</td><td>" . $row['zipcode'] . "</td></tr>";
            echo "<tr><td>Address</td><td>" . $row['street'] . "</td></tr>";
            echo "<tr id='cell'><td>Description</td><td>" . $row['summary'] . "</td></tr>";
            echo "<tr><td>Url</td><td>" . $row['url'] . "</td></tr>";
            echo "<tr id='cell'><td>Start</td><td>" . $row['start'] . "</td></tr>";
            echo "<tr><td>End</td><td>" . $row['end'] . "</td></tr>";
        
        return true;
    
   

提前感谢您的帮助

更新

我之前发布的错误可能与我的 VM 和 cassandra 崩溃有关，无论哪种方式，我仍然需要检查空结果。

谢谢

更新

按照发布的建议，我最终做了以下事情

function check_key($key)
    try
        $cluster = Cassandra::cluster()->build();
        //set this to the appropriate keyspace
        $keyspace = 'loop_non_hadoop'; 
        $session = $cluster->connect($keyspace);
        $query = "SELECT * FROM events WHERE key=$key";
        $statement = new Cassandra\SimpleStatement($query);

        $results = $session->execute($statement);

        foreach ($results as $row) 
            echo "<tr id='cell'><td>Title</td><td>" . $row['title'] . "</td></tr>";
            echo "<tr><td>Location</td><td>" . $row['locationName'] . "</td></tr>";
            echo "<tr id='cell'><td>City</td><td>" . $row['city'] . "</td></tr>";
            echo "<tr><td>State</td><td>" . $row['state'] . "</td></tr>";
            echo "<tr id='cell'><td>Zip</td><td>" . $row['zipcode'] . "</td></tr>";
            echo "<tr><td>Address</td><td>" . $row['street'] . "</td></tr>";
            echo "<tr id='cell'><td>Description</td><td>" . $row['summary'] . "</td></tr>";
            echo "<tr><td>Url</td><td>" . $row['url'] . "</td></tr>";
            echo "<tr id='cell'><td>Start</td><td>" . $row['start'] . "</td></tr>";
            echo "<tr><td>End</td><td>" . $row['end'] . "</td></tr>";
        
        return true;
    
    catch(Exception $e)
        //Casandra error
        var_dump($e->getMessage());
    
    finally 
        return;
    

感谢您的建议

【参考方案1】：

使用try catch:

function check_key($key)
    try
        $cluster = Cassandra::cluster()->build();
        //set this to the appropriate keyspace
        $keyspace = 'loop_non_hadoop'; 
        $session = $cluster->connect($keyspace);
        $query = "SELECT * FROM events WHERE key=$key";
        $statement = new Cassandra\SimpleStatement($query);

        $results = $session->execute($statement);

        if(empty($results))
            return;
        
        else 
            foreach ($results as $row) 
                echo "<tr id='cell'><td>Title</td><td>" . $row['title'] . "</td></tr>";
                echo "<tr><td>Location</td><td>" . $row['locationName'] . "</td></tr>";
                echo "<tr id='cell'><td>City</td><td>" . $row['city'] . "</td></tr>";
                echo "<tr><td>State</td><td>" . $row['state'] . "</td></tr>";
                echo "<tr id='cell'><td>Zip</td><td>" . $row['zipcode'] . "</td></tr>";
                echo "<tr><td>Address</td><td>" . $row['street'] . "</td></tr>";
                echo "<tr id='cell'><td>Description</td><td>" . $row['summary'] . "</td></tr>";
                echo "<tr><td>Url</td><td>" . $row['url'] . "</td></tr>";
                echo "<tr id='cell'><td>Start</td><td>" . $row['start'] . "</td></tr>";
                echo "<tr><td>End</td><td>" . $row['end'] . "</td></tr>";
            
            return true;
        
    catch(\Exception $e)
        //Casandra error
        var_dump($e->getMessage());
    
 

【讨论】：

我会试试的，谢谢。对 PHP 相当陌生