Why Caching A DataBase Connection Is A Bad Idea






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Feb 11, 2002
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Caching Data in Application or Session objects is a good idea. Caching Database connections in Application or Session objects however is not a good idea. This article explains why and how to best use your database connections.
While caching data in the Application
or Session
object can be a good idea, caching database connections is usually a bad one.
Take for example the Connection
object, if you store a connection in a Session
object, you no longer have the benefit of connection pooling. Connection pooling
is beneficial when connections are shared across multiple clients and resources
are in use only as long as they are needed i.e. If the Connection
object is
stored in the ASP Session
object, then a database connection will be created for
every user. Similarly, if one Connection
object is stored in the Application
object and used on all pages, then all pages will contend for use of this
connection. This puts unnecessarily high stress on both the Web server and the
database.
Instead of caching database connections, create and destroy ADO objects on every ASP page that uses ADO. This is efficient because IIS has database connection pooling built in. More accurately, IIS automatically enables OLEDB and ODBC connection pooling. This ensures that creating and destroying connections on each page will be efficient.
Since connected recordsets store a reference to a
database connection, it follows that you should not cache connected recordsets
in the Application
or Session
objects. However, you can safely cache
disconnected recordsets, which don't hold a reference to their data connection.
To disconnect a recordset, take the following two steps:
Set rs = Server.CreateObject("ADODB.RecordSet")
rs.CursorLocation = adUseClient ' step 1
' Populate the recordset with data
rs.Open strSQL, strProv
' Now disconnect the recordset from the data provider and data source
rs.ActiveConnection = Nothing ' step 2