Tool for instantiating a C++ template at runtime?

I'm working on a query engine, essentially a tool to scan/filter/annotate by lookups/group by/aggregate a large dataset, tens-of-terabytes range. The compute part seems to be a bottleneck for me (I'll be doing around 80-300 GB/s of reads, and yes, I will have hardware capable of providing that kind of throughput). My hypothesis is that by encoding query in form of template arguments I can make the compiler generate code optimized for a specific type of query (like, the filtering or aggregation keys). But I do not know what queries will users send, so I need a way to instantiate templates at runtime.

Sounds simple: for a new type of query invoke a compiler at runtime to build a dynamic library with a new instantiation, then dynload it and off we go. Some prior work is here, though I'm pretty sure any JIT compiler also can counts here. But there's enough technical details to worry about, and at the same time this idea isn't novel, so I wonder—are there any packaged solutions for this kind of approach?