I'm successfully using ZF2.2
Everything was working fine until a requirement arised to close the sql connection explicitly.
I know PHP closes all extra db connections after some time.
But I wanted to do this explicity something like $adapter->closeConnection();
Please tell me there is something which can help me.
If you have the adapter in $adapter, this should work:
$adapter->getDriver()->getConnection()->disconnect();
You should get the db_adapter and then get the connection (getConnection()) and with this object you will be able to use the disconnect() method.
Related
i'm using Slim framework to provide an API to our clients. I'm focused on Java so that could the the point, because the problem is related with database connection.
Every request connect to the database throw PDO like
$dbh = new PDO($param1, $param2, $param3);//php 7.1
So as php don't have a connection pool i understand each request (maybe at the same time) starts a new connection throw the database.
But i'm experimenting a kind of situation here.
If one request starts a transaction for inserting or updating something, next requests will wait until this transaction finish, but it is on a different thread, so i'm thinking on table locks? or something like each request is getting the same connection.
THE PROBLEM:
So if they are in different threads with a different connection how
they need to wait until transaction ends for the first request.
My database source class is something like
class DataBaseConfig {
public static function getConn()
{
$dbh = new PDO($param1, $param2, $param3);
$dbh->exec("set names utf8");
return $dbh;
}
}
And i use it like
$db = DataBaseConfig::getConn();
$db->beginTransaction();
//code
$db->commit();
I'm missing something sure, so can someone help me with this problem?
Thanks!
NEWS! EDIT
#YourCommonSense thank you it was finally a session configuration. I
didn't know that php start_session(); locks the session file so that's
what was happening. Thanks a lot!
link: https://ma.ttias.be/php-session-locking-prevent-sessions-blocking-in-requests/
I am doing project using mongodb and zendframework 2 so here I create connection in the constructor
private $conn;
public function __construct(){
$this->conn = new \MongoClient('mongodb://example.com:27017', array("connect" => TRUE));
}
It contain several actions to perform database operations like createdb, dropdb, renamedb like wise. so I close that connection within the __distruct() method
public function __destruct(){
$this->conn->close();
}
my code works fine. but I would like to know is this ok?
PHP closes database connections automatically.
You can read more about this in this post
however
read this
quote:
"Open connections (and similar resources) are automatically destroyed at the end of script execution. However, you should still close or free all connections, result sets and statement handles as soon as they are no longer required. This will help return resources to PHP and MySQL faster."
So basically, in case you have tons of things going in and out of the database, then yes, you might want to close right after.
In my opinion it is rather optional and your own choice wether to kill the process or not.
I am using Zend Framework for my PHP developments and here is a small function I used to execute a query. This is not about an error. The code and everything works fine. But I want to know some concept behind this.
/**
* Get dataset by executing sql statement
*
* #param string $sql - SQL Statement to be executed
*
* #return bool
*/
public function executeQuery($sql)
{
$this->sqlStatement = $sql;
if ($this->isDebug)
{
echo $sql;
exit;
}
$objSQL = $this->objDB->getAdapter()->prepare($sql);
try
{
return $objSQL->execute();
}
catch(Exception $error)
{
$this->logMessage($error->getMessage() . " SQL : " .$sql);
return false;
}
return false;
}
Bellow are unclear areas for me.
How Zend_Db_Table_Abstract Maintain database connections?
Is it creating new connection all the time when I call this function or Does it have some connection pooling?
I didn't write any coding to open or close database connection. So will zend framework automatically close connections?
If this open and close connection works all the time if I execute this function, Is there any performance issue?
Thank you and appreciate your suggestions and opinion on this.
Creating Connection
Creating an instance of an Adapter class does not immediately connect to the RDBMS server. The Adapter saves the connection parameters, and makes the actual connection on demand, the first time you need to execute a query. This ensures that creating an Adapter object is quick and inexpensive. You can create an instance of an Adapter even if you are not certain that you need to run any database queries during the current request your application is serving.
If you need to force the Adapter to connect to the RDBMS, use the getConnection() method. This method returns an object for the connection as represented by the respective PHP database extension. For example, if you use any of the Adapter classes for PDO drivers, then getConnection() returns the PDO object, after initiating it as a live connection to the specific database.
It can be useful to force the connection if you want to catch any exceptions it throws as a result of invalid account credentials, or other failure to connect to the RDBMS server. These exceptions are not thrown until the connection is made, so it can help simplify your application code if you handle the exceptions in one place, instead of at the time of the first query against the database.
Additionally, an adapter can get serialized to store it, for example, in a session variable. This can be very useful not only for the adapter itself, but for other objects that aggregate it, like a Zend_Db_Select object. By default, adapters are allowed to be serialized, if you don't want it, you should consider passing the Zend_Db::ALLOW_SERIALIZATION option with FALSE, see the example above. To respect lazy connections principle, the adapter won't reconnect itself after being unserialized. You must then call getConnection() yourself. You can make the adapter auto-reconnect by passing the Zend_Db::AUTO_RECONNECT_ON_UNSERIALIZE with TRUE as an adapter option.
Closing a Connection
Normally it is not necessary to close a database connection. PHP automatically cleans up all resources and the end of a request. Database extensions are designed to close the connection as the reference to the resource object is cleaned up.
However, if you have a long-duration PHP script that initiates many database connections, you might need to close the connection, to avoid exhausting the capacity of your RDBMS server. You can use the Adapter's closeConnection() method to explicitly close the underlying database connection.
Since release 1.7.2, you could check you are currently connected to the RDBMS server with the method isConnected(). This means that a connection resource has been initiated and wasn't closed. This function is not currently able to test for example a server side closing of the connection. This is internally use to close the connection. It allow you to close the connection multiple times without errors. It was already the case before 1.7.2 for PDO adapters but not for the others.
More information
I have a webpage with some mysql querys,
I must start new db connection and db close after every query or its more efficiently start an only one db connection at the top of the code and close at the bottom of the script?
Thanks!
Never create a new connection for every query; it's very wasteful and will overburden your MySQL server.
Creating one connection at the top of your script is enough - all subsequent queries will use that connection until the end of the page. You can even use that connection in other scripts that are include()ed into the script with your mysql_connect() call in it.
I prefer to create some sort of class called Database of which upon creation will create a database connection using mysqli (OOP version of mysql).
This way i do not have to worry about that and i have a static class that has access to the database.
class MyAPI {
private static $database = false;
public static function GetDatabase() {
if (MyAPI::$database === false) {
MyAPI::$database = new Database(credentials can go here)
}
return MyAPI::$database;
}
}
Now your system with the includsion of your API and your database can access the database and its initialization code does not have to be peppered around your files depending on what part of the program is running and your database/connection will not be created if it is not needed (only until it is called).
Just for fun i also like to have a function in my Database class that will perform a query and return its results, this way i do not have to have the SAME while loop over and over again throughout my code depending on where i make these calls.
I also forgot to answer your question. No multiple connections! its baaaad.
Only create one connection. You don't even have to close it manually.
multiple connexion is better for security and tracking.
if you're going though a firewall between front and back there will be a timeout defined so a single connection will be a problem.
but if your web server is on the same host as mysql, a single connection will be more efficient.
I'm using PDO to access two SQLite 3 databases in PHP. I want to switch the database files during a query by renaming them but I can't do that while the files are open as it gives an error that the file is being used by another process. I've tried turning off persistent connections and setting the handles to null but neither work.
Is there really no way to close a PDO handle and release the lock on the database file?
I believe unset($var) does that, I use it on my pdo sqlite project and it works like I want it to :)
Set all references to the handle to null (or to anything except the PDO object, really) and the runtime will destruct the object, which will close the connection.
$db = new PDO('...');
// Do some stuff
$db = null;
// Assuming this was the last reference to that PDO
// object, the runtime will destroy the object and
// its connection.