Postgres Npgsql Connection Pooling
I'd like to better understand Connection Pooling when using Npgsql for Postgres. (http://www.npgsql.org/)
When I use the connection string:
UserID=root;Password=myPassword;Host=localhost;Port=5432;Database=myDataBase;Pooling=true;Minimum Pool Size=0;Maximum Pool Size=100;
Where is the "Pooling" going to take place? On my application server or on the database?
When I call connection.Open(), what happens? Is a connection taken from the pool if one exists and if not, a pool is created?
Any other general info around Connection Pooling would be appreciated.
Thanks.
Answer
Npgsql connection pooling is implemented inside your application process - it has nothing to do with PostgreSQL, which is completely unaware of it.
The mechanism is very simple. When you close a pooled connection, instead of physically closing the connection to PostgreSQL the physical connection is kept around idle in memory (in a "pool"). The next time you open a new connection, if its connection string matches a physical connection already present in the pool, that physical connection is reused instead of opening a new physical connection.
Since opening/closing physical connections is an expensive process, this considerably speeds up your application.