Hi hackers, Vik Fearing asked off-list why hash joins appear to read slightly more temporary data than they write. The reason is that we notch up a phantom block read when we hit the end of each file. Harmless but it looks a bit weird and it's easily fixed.
Unpatched, a 16 batch hash join reports that we read 30 more blocks than we wrote (2 per batch after the first, as expected): Buffers: shared hit=434 read=16234, temp read=5532 written=5502 With the attached patch: Buffers: shared hit=547 read=16121, temp read=5502 written=5502 -- Thomas Munro http://www.enterprisedb.com
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