Connecting to any database from code is
a time consuming process. Of course,may not be more than few milliseconds but when thousands of users are accessing your website it
will affect the performance of the application.Similar database
connections will be opened and closed to perform the client requests.
To optimize the creation and
utilization of data base connections ADO.NET provided a concept
called connection pooling.If
connection polling is enabled and user calls connection Open,
instead of directly creating
the connection, the ADO.NET will first check if there are any active
connections in the pool,If any active connections are available it
will return the connection from the pool otherwise a new connection
will be created.When the application Close the
connection it will be returned to the pool.
Connection
pools are created based on Connection strings.Two connection pools
will be created if two connection strings differed even in the order
of connection properties though their values are same.
By
Default connection Pooling is Enabled in ADO.NET
Below
are the important Connection Pooling attributes or properties.
Pooling:When
its true,A connection
will be created in the first request and will be returned to the pool
after its usage.
Connection
Lifetime (or Load Balance Timeout): Life time of the active
connections in the pool.If a connection exceeds this value then
connection will be destroyed. This time out is useful in load balance
scenarios.
Default
value is 0 seconds. Value 0 causes the maximum time out for
connections.
Connection
Timeout: Maximum time the connection waits for response to be
returned by the server. Default value is 15 seconds.
Enlist:
When Enlist is true, pooler enlists the connection in creation
threads current transaction context.
Max
Pool Size: Indicates the maximum number of connections allowed inside
the connection pool. Default value is 100. Max Pool Size should
always be greater than or equal to Min Pool Size.
Min
Pool Size:Indicates the minimum number of connections allowed inside
the pool.Default value is 0. Min Pool Size should always be less than
or equal to Max Pool Size.
Sample
connection string with
connection pooling:
<add
name="SampleConnectionString"
connectionString="Data
Source=localhost;Initial Catalog=SampleDataBase;Persist Security
Info=True;User ID=sa;Password=Sky#1;Connection Timeout=30;Min
Pool Size=5;Max Pool Size=20;Pooling=True;Connection
Lifetime=0;Enlist=True;"
providerName="System.Data.SqlClient"
/>
