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POSQLite/C# Connection Pooling and Prepared Statement Confusion
 

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    <p>I have been spending some time reading different best practices for databases and for SQLite specifically. While reading I found I was doing many things I shouldn't be doing and when attempting to fix these issues I became confused when thinking about some of the finer details of using SQLite with it's ADO implementation.</p> <p>My confusion stems specifically from prepared statements and connection pooling. </p> <p>While reading <a href="http://msdn.microsoft.com/en-us/library/ms971481.aspx" rel="nofollow noreferrer">http://msdn.microsoft.com/en-us/library/ms971481.aspx</a> I found that connections should only be opened for a transaction. Once the transaction is complete then the connection should be closed. I do not have a firm grasp as to why this is the case, but I have been working off the assumption that the author(s) know better then I. I understand that when a connection is closed it doesn't mean it has actually been closed. It simply means that it has been put back into the pool.</p> <p>Now to improve my queries and inserts I read about using prepared statements. <a href="https://stackoverflow.com/questions/1703203/in-sqlite-do-prepared-statements-really-improve-performance">In SQLite, do prepared statements really improve performance?</a> and <a href="http://petesbloggerama.blogspot.com/2007/02/sqlite-adonet-prepared-statements.html" rel="nofollow noreferrer">http://petesbloggerama.blogspot.com/2007/02/sqlite-adonet-prepared-statements.html</a> both seemed to indicate that when executing a query that will be done multiple times prepared statements are the way to go. I have also read that a prepared statement is specific to a connection and that once the connection is closed the prepared statement is lost.</p> <p>My confusion is this. If I am opening and closing my connection (which may or may not mean the connection is being closed due to the thread pool) then how much use am I really getting from a prepared statement? I can understand that if I have 1000 objects I need to save in a single transaction that the prepared statement can help a lot. However I don't believe I would see a benefit from saving a single object in a transaction because once I close the connection the prepared statement that was generated from the first object is now lost. Is this a true statement?</p> <p>My confusion is furthered by the fact that I believe a prepared statement is linked to the scope of my SQLiteCommand object.</p> <p>If I create a SQLiteCommand that represents a query that I will be executing often do I need to keep that SQLiteCommand in memory for the prepared statement to stay active?</p> <p>If I create a new SQLiteCommand with the same SQLite statement is it recognized that the new SQLiteCommand is the same as the previous and thus has a prepared statement that can be used?</p> <p>If I keep a SQLiteCommand in memory and change it's parameters and connection as I open and close the connection for different transactions am I essentially keeping a prepared statement alive between different connections?</p> <p>I am most likely over thinking things at this point but I hope you can help me better understand how these things interact so I can get the most benefit out of them.</p>
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    1. COI'm not well versed in SQLite, but with respect to why one should close connections ASAP, you came rather close to answering it yourself: The underlying physical connection isn't closed, you merely return the connection to the pool. The implication is that it can be used by other threads. Clearly, if you hang on to a connection but don't actually use it, that will limit the maximum possible utilization. (Equally clearly: if you're in a single-threaded context, connection pooling doesn't make a whole lot of sense, though it is unlikley to hurt you much.)
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