Robert Haas <robertmh...@gmail.com> writes: > On Mon, Jun 16, 2014 at 8:10 PM, Tom Lane <t...@sss.pgh.pa.us> wrote: >> On a micro-optimization level, it might be worth passing the TID as >> ItemPointer not ItemPointerData (ie, pass a pointer until we get to >> the point of actually inserting the TID into the index tuple). >> I'm not sure that copying odd-size structs should be assumed to be >> efficient.
> Yeah, true. Checking existing precedent, it looks like we usually > pass ItemPointer rather than ItemPointerData, so it's probably a good > idea to do this that way too for reasons of style if nothing else. I > kind of wonder whether it's really more efficient to pass an 8-byte > pointer to a 6-byte structure than to just pass the structure itself, > but it might be. The pointer will certainly be passed in a register, or whatever passes for registers on the particular machine architecture. Weird-size structs, though, tend to have arcane and not-so-efficient rules for being passed by value. It's not unlikely that what the compiler will do under the hood is pass a pointer anyhow, and then do a memcpy to make a local copy in the called function. regards, tom lane -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers