On Thu, Dec 22, 2011 at 12:38 PM, Robert Newson <[email protected]> wrote:
> It reads well as an article but needs some polish before it could be a > great wiki page. I suggest that if it does go up, it is clearly marked > as a draft, and we all chip in to sculpt it into shape. > Great idea. Agreed that it is no where as clean/factual as it would need to be for an appropriate wiki/ref-doc-style entry, but if it can be massaged into that, it would hopefully make a great resource. > There are a > few parts of the article that are inaccurate (like the assertion we > have good locality for the id and seq trees. If this were true we > wouldn't have seen such a huge improvement in compaction by > temporarily separating them). I'd look forward to more detail on this... it was my understanding the updates were appended out in the [doc rev][_id idx diff][_seq idx diff] format at the end of the data file. Sounds like I may have misunderstood that? > The 'COMPETE recreation' paragraph also > strikes me as factually awry. > I'd appreciate a detailed correction on this if it is wrong; all the digging I've done (in this thread and other partial resources) suggests that the path from the changed doc ref back to the root (including a copy of all internal nodes and all of their child references) is written so as being able to read-back into the index from the tail of the data file quickly... specifically slides 17, 18 and 19 from this slidedeck ( http://www.slideshare.net/jchrisa/btree-nosql-oak?from=embed) -- note that the interim nodes [A..M] and [A..Z] are rewritten (including any and all child pointers they contained). This is what I was referring to; I should either clean up my wording (confusing) or I got it wrong in which case I'd appreciate any and all corrections. Thanks for helping move this forward and the feedback Robert. -Riyad
