None at the moment, but I'm open to suggestions. It seems like we might need different stats for equality probes than range probes.
What about my suggestion from August 2000:
"There might be a way to side-step the issue here. I assume that the index nodes contain a pointer to a record in a file, which has some kind of file position. By comparing the file positions on one leaf node, and then averaging the node cluster values, you might be able to get a pretty good idea of the *real* clustering."
I don't use the CLUSTER command, but I have clustered data and would like to be able to take advantage of the fact if possible. *If* the record pointers can be used to indicate closeness, then the same approach of randomly sampling index nodes would seem to work. Then again, maybe I don't know enough about the storage techniques...
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