[英]Cassandra Prepared Statements error with datastax php driver
我在使用 DataStax php 驅動程序 1.0.0-rc 和 Cassandra 2.2.3 的 Prepared Statements 時遇到了奇怪的錯誤。 我在這條線上得到了一個例外:
$statement = $this->session->prepare("SELECT ? FROM ? WHERE ? = ?");
我看到這個錯誤:
"error_code":33562624
"error_message":"Bind variables cannot be used for keyspace names"
下面是用於與 Cassandra 通信的類的存根:
class ClsCassandra extends ClsDbObject
{
private $hostname="";
private $username="";
private $password="";
private $keyspace="";
private $poi_table="";
private $poi_table_key_field="";
private $poi_table_content_field="";
private $cluster = NULL;
private $session = NULL;
private $threads = 1;
function __construct()
{
...
...
//
// i set up all the properties above
//
...
...
}
public function runQuery(&$error)
{
try
{
$this->cluster = Cassandra::cluster()
->withContactPoints($this->hostname)
->withCredentials($this->username, $this->password)
->withIOThreads($this->threads)
->build();
$this->session = $this->cluster->connect($this->keyspace);
// error on next line...
$statement = $this->session->prepare("SELECT ? FROM ? WHERE ? = ?");
$results = $this->session->execute($statement, new Cassandra\ExecutionOptions(array(
'arguments' => array($this->poi_table_content_field, $this->poi_table, $this->poi_table_key_field, $keypattern)
)));
}
catch(Cassandra\Exception $ce)
{
$error->setError($ce->getCode(), $ce->getMessage(), $ce->getTraceAsString());
$this->log(LOG_LEVEL, $error->getErrorMessage(), __FILE__, __LINE__, __CLASS__);
return false;
}
return true;
}
...
...
...
}
如果我將 Simple Statemetn 與標准選擇查詢一起使用,則它可以工作。
有什么建議?
您看到此錯誤是因為您只能將變量綁定到 WHERE 子句。 准備好的語句機制不僅僅是一個美化的字符串格式化程序。 它有關於什么可以綁定和什么不能綁定的規則,以及在發送到 Cassandra 時你必須如何綁定以消除任何歧義。
你需要嘗試這樣的事情:
$statement = $this->session->prepare(
"SELECT key1, key2, col1, col2 FROM yourKeyspaceName.yourTableName WHERE key1 = ? AND key2 = ?");
$results = $this->session->execute($statement, new Cassandra\ExecutionOptions(array(
'arguments' => array($key1,$key2)
)));
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