> I took at a first crack at coding up an implementation of > relation_is_distinct_for() tonight.
I am not sure if this will help or not, but on the 8.4 code base we implemented two functions: - getCandidateKeys() - would recursively traverse a tree from a given node to the leaf nodes and determine the candidate keys for the intermediate relation produced by that node - getJoinCard() - determined the join cardinality of a hash join node (1:1, 1:N, etc.) based on the candidate keys of the two input relations It worked pretty well for our tests with equi-joins, but I am sure it is missing many cases. I have attached the code which we used (cardinalityFuncs.c). Some of the helper functions may also be useful (convertUniqueIndexesToCandidateKeys, getJoinAttrs). -- Ramon Lawrence
cardinalityFuncs.c
Description: cardinalityFuncs.c
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