Jim C. Nasby wrote: >> No, hash joins and hash indexes are unrelated.
I know they are now, but does that have to be the case?
I mean, the algorithms are fundamentally unrelated. They share a bit of code such as the hash functions themselves, but they are really solving two different problems (disk based indexing with (hopefully) good concurrency and WAL logging vs. in-memory joins via hashing with spill to disk if needed).
Like I said, I don't know the history, so I don't know why we even have them to begin with.
As I said, the idea of using hash indexes for better performance on equality scans is perfectly valid, it is just the implementation that needs work.
-Neil
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