Simulator; only modified postgresql optimizer

Hi,

There was a project done over Postgresql 9.1.1 - it is a preference aware
query optimizer. It consists of modified parser(which provides the users
with an option for additional parser syntax) and modified optimizer(early
prunning, additional cost metric). It is generating optimized plan.

My task now is to migrate only the modified optimizer and develop it
further on 10.4. This means that I will have to input directly a parser
tree to the optimizer module and output the new tree generated by the
optimizer.

How can I efficiently approach such a simulator? I mean, I will need only
to provide specific trees to the optimizer module and return results, not
to develop a whole new version of postgresql dbms. In general, when I was
developing over the whole postgresql it was fine as I can create a db in
the regular dbms and then just compile the modified files and start it
again over the already created database. Now I am really not sure what
should be the right and smart approach.

Can you share any advice/information/links/articles, please?

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