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authorTom Lane <tgl@sss.pgh.pa.us>2006-06-07 17:08:07 +0000
committerTom Lane <tgl@sss.pgh.pa.us>2006-06-07 17:08:07 +0000
commitae0c8d09fb05d39c4f2c548bfc4720dadbd83532 (patch)
tree41c52c469cf75c5207158592862ac6fb95f8957a /src/backend/executor/nodeAppend.c
parentca9d50304ff664ec2fbf6ddf4cafe3d031c319cb (diff)
Remove "fuzzy comparison" logic in qsort comparison function for
choose_bitmap_and(). It was way too fuzzy --- per comment, it was meant to be 1% relative difference, but was actually coded as 0.01 absolute difference, thus causing selectivities of say 0.001 and 0.000000000001 to be treated as equal. I believe this thinko explains Maxim Boguk's recent complaint. While we could change it to a relative test coded like compare_fuzzy_path_costs(), there's a bigger problem here, which is that any fuzziness at all renders the comparison function non-transitive, which could confuse qsort() to the point of delivering completely wrong results. So forget the whole thing and just do an exact comparison.
Diffstat (limited to 'src/backend/executor/nodeAppend.c')
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