On 09/25/2014 05:40 PM, Andres Freund wrote:
There's two reasons for that: a) dynahash just isn't very good and it does a lot of things that will never be necessary for these hashes. b) the key into the hash table is*far* too wide. A significant portion of the time is spent comparing buffer/lock tags.
Hmm. Is it the comparing, or calculating the hash? We could precalculate the hash for RelFileNode+ForkNumber, and store it RelationData. At a lookup, you'd only need to mix in the block number.
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