Narendra Pradeep U U <narendra.prad...@zohocorp.com> writes: > Recently I came across a case where the planner choose larger table on > hash side. I am not sure whether it is an intended behavior or we are > missing something.
Probably the reason is that the smaller table has a less uniform
distribution of the hash key. You don't want to hash with a nonuniform
distribution of the hashtable key; if many keys go into the same bucket
then performance degrades drastically.
regards, tom lane
