Re: POC, WIP: OR-clause support for indexes

I agree with your code in general, but to be honest, double qsort confused me a little. 

I understood why it is needed - we need to sort the elements so that they stand next to each other if they can be assigned to the same group, and then sort the groups themselves according to the set identifier. 

I may be missing something, but in the worst case we can get the complexity of qsort O(n^2), right? And I saw the letter where you mentioned this, but it is possible to use mergesort algorithm  instead of qsort, which in the worst case gives n * O(n) complexity?

No, sorry, I was wrong here and it is impossible to rewrite it this way. I apologize, I agree with your code.

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Regards,
Alena Rybakina
Postgres Professional