On Sun, Dec 6, 2015 at 4:25 PM, Peter Geoghegan <p...@heroku.com> wrote:
> Maybe we should consider trying to get patch 0002 (the memory > pool/merge patch) committed first, something Greg Stark suggested > privately. That might actually be an easier way of integrating this > work, since it changes nothing about the algorithm we use for merging > (it only improves memory locality), and so is really an independent > piece of work (albeit one that makes a huge overall difference due to > the other patches increasing the time spent merging in absolute terms, > and especially as a proportion of the total). I have a question about the terminology used in this patch. What is a tuple proper? What is it in contradistinction to? I would think that a tuple which is located in its own palloc'ed space is the "proper" one, leaving a tuple allocated in the bulk memory pool to be called...something else. I don't know what the non-judgmental-sounding antonym of postpositive "proper" is. Also, if I am reading this correctly, when we refill a pool from a logical tape we still transform each tuple as it is read from the disk format to the memory format. This inflates the size quite a bit, at least for single-datum tuples. If we instead just read the disk format directly into the pool, and converted them into the in-memory format when each tuple came due for the merge heap, would that destroy the locality of reference you are seeking to gain? Cheers, Jeff -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
