Optimize data structures in SelectResultValueBuilder

[leventov]

MinMaxPriorityQueue is never needed. Also, when there is no threshold of the number of results, it's practically faster better to aggregate results in an ArrayList from the beginning and then sort in the end, than aggregate in a priority queue (because quick sort is considered faster than heap sort).

Also, I don't understand the meaning of pagingIdentifiers - it's not explained anywhere. Is it important for this Map to put entries in order?

[gianm]

@leventov are you using the Select query today? In general it is worse than the Scan query, except in one way - it supports time ordering. But we can add that to Scan as well. See #5006, #6088.

[leventov]

@gianm no, we don't - I was just passing by this code. However still curious about pagingIdentifiers

[gianm]

I'm not super familiar with how the pagingIdentifiers work exactly, but I think the idea is they represent cursors into specific segments, and are used when you have a paginated select query. I am not sure if the order matters, but I would guess no.

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