> What's strange about it? A probe into an in-memory hashtable is a lot > cheaper than a probe into an index, so this type of plan makes plenty > of sense if the hashtable will fit in RAM and there are going to be a > lot of probes. (Where "a lot" means "enough to amortize the cost of > building the hashtable", of course.)
Hmm... it didn't occur to me that the index probe itself might be more expensive than a hash probe. Is that due to concurrency control, or are you talking about the need to possibly read index pages in from disk? >> Experimentation shows this is actually about 25% faster. > > Well, that just says your cost parameters need a bit of adjustment > if you'd like the planner to get the crossover point exactly right. Any sense of which ones might be worth fiddling with? ...Robert -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
