From: Phillip Wood Date: Fri, 19 Nov 2021 10:05:32 GMT Subject: Re: [PATCH 1/3] diff histogram: intern strings Message-ID: <86d38148-7b97-76aa-148b-346cc179615a@gmail.com> In-Reply-To: On 18/11/2021 15:42, Jeff King wrote: > On Thu, Nov 18, 2021 at 04:35:48PM +0100, Johannes Schindelin wrote: > >> I think the really important thing to point out is that >> `xdl_classify_record()` ensures that the `ha` attribute is different for >> different text. AFAIR it even "linearizes" the `ha` values, i.e. they >> won't be all over the place but start at 0 (or 1). >> >> So no, I'm not worried about collisions. That would be a bug in >> `xdl_classify_record()` and I think we would have caught this bug by now. > > Ah, thanks for that explanation. That addresses my collision concern from > earlier in the thread completely. Yes, thanks for clarifying I should have been clearer in my reply to Stolee. The reason I was waffling on about file sizes is that there can only be a collision if there are more than 2^32 unique lines. I think the minimum file size where that happens is just below 10GB when one side of the diff has 2^31 lines and the other has 2^31 + 1 lines and all the lines are unique. Best Wishes Phillip