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Executing ad-hoc queries with RavenDB
time to read 1 min | 50 words
I just managed to solve the most annoying problem with implementing this feature, which is how to successfully run the queries in a separate AppDomain without serializing all the data:
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Wow, what a code. Looks like you have yet to work on ad-hoc query feature.
Just a question, why would I want to run a query from a different AppDomain?
Am I understanding this right -- you're "serializing" to the database instead of across app domains? If so, then how is this faster? Aren't you trading memory access for network access?
Why not simply use MarshalByRefObjects to contain the data that would have been serialized?
I'm curious, what use-case does an ad-hoc query have? Are these designed to be used e.g., by an administrator inspecting data in the document store, who wants to be able to query and filter the data? Or, are these actually intended for use by client code?
Oh, you are using them - the QueryRunner is one. Am I right here?
Can you please elaborate? It is clear that there was a query from a different AppDomain, but it is not clear what is actually serialized.
Also please explain if this is a feature or just an optimization for the different AppDomain use case.
Thanks.
@Nathan, RavenDB compiles queries dynamically, but the runtime compiles them to a new assembly. Since unloading assemblies at run time isn't supported, those assemblies generated from the queries will stick around for the lifetime of the server instance - that's a memory leak. Unloading entire AppDomains IS supported, though - so the only way to avoid this memory leak is to load the assemblies in a new AppDomain, and then unload it when it's no longer needed.
I believe using Reflection.Emit instead of Expression.Compile would also avoid it (because you're creating a DynamicMethod instance, not a new assembly), but that would require writing a library to generate IL for arbitrary expression trees, which is a potentially arduous undertaking.
I LOVE your understatement
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