Tomas, * Tomas Vondra (t...@fuzzy.cz) wrote: > However it's likely there are queries where this may not be the case, > i.e. where rebuilding the hash table is not worth it. Let me know if you > can construct such query (I wasn't).
Thanks for working on this! I've been thinking on this for a while and this seems like it may be a good approach. Have you considered a bloom filter over the buckets..? Also, I'd suggest you check the archives from about this time last year for test cases that I was using which showed cases where hashing the larger table was a better choice- those same cases may also show regression here (or at least would be something good to test). Have you tried to work out what a 'worst case' regression for this change would look like? Also, how does the planning around this change? Are we more likely now to hash the smaller table (I'd guess 'yes' just based on the reduction in NTUP_PER_BUCKET, but did you make any changes due to the rehashing cost?)? Thanks, Stephen
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