Hi,
Can we support loser tree first and set the default value of enable_loser_tree to off?
Anyway, I attach 2 patches. (pass check-world)
v2-0001: support tuplesort_heap_build() which can build a valid heap in O(n), better
than currently O(n log n). This also make beginmerge() more clear and simple when
supporting loser tree.
v2-0002: support the loser tree.
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Regards,
ChangAo Chen
