NpgsqlCommand.Dispose() should execute "DEALLOCATE <name>" for a prepared command about npgsql HOT 3 CLOSED

I think you have a good point here.

I think this issue didn't appear before because we are always asking users to use the pattern of open the connection, use it and then close it. This way, it isn't normal to accumulate too much prepared statements.

Another point is that we discouraged the use of prepared statements because they had poor performance. Now that Glen added a lot of optimizations, I think more and more prepared statements will be used and this issue may start to be noticed.

Thank you very much, Udo, for bringing our attention to this. We will work on it for the 2.2 release. I'll add a milestone to indicate that.

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Guys, this is a pretty important item, I'll take a look at it, hopefully it will make it into 2.2.

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Implementation note to self: we can't do any sort of database interaction from with Dispose() (i.e. DEALLOCATE) since when executed from the finalizer (can be whenver) this causes contention on the database connection with whatever query is actually being executed.

Can't lock either, since any sort of blocking within a finalizer is a big no-no.

So need to push the DEALLOCATE to a queue to be processed at the earliest convenience. It would be nice to be able to check, from Dispose(), whether the connection is in use (TryLock) and have a fast-path, but there's no such lock currently in Npgsql. This mechanism would also be relevant for #270.

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