Re: Group-count estimation statistics

>>>>> "Tom" == Tom Lane <tgl@sss.pgh.pa.us> writes:

    Tom> The only real solution, of course, is to acquire cross-column
    Tom> statistics, but I don't see that happening in the near
    Tom> future.

Another approach is a hybrid hashing scheme where we use a hash table
until we run out of memory at which time we start spilling to disk. In
other words, no longer use SortAgg at all ..

Under what circumstances will a SortAgg consumer more IOs than a
hybrid hash strategy ?

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Sailesh
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