I have been researching bloom filters and discussed it on IRC with RhodiumToad and David Fetter, and they pointed me to the various places that could potentially have bloom filters, apart from the places that already have them currently.
I have been reading the current implementation of hash joins, and in ExecScanHashBucket, which I understand is the actual lookup function, we could potentially look at a bloom filter per bucket. Instead of actually looking up each hash value for the outer relation, we could just check the corresponding bloom filter for that bucket, and if we get a positive, then lookup the actual values i.e. continue with our current behaviour (since we could be looking at a false positive).
Exactly this was suggested by me on the NTUP_PER_BUCKET thread last week.
