On Sat, Mar 25, 2017 at 10:13 AM, Mithun Cy <mithun...@enterprisedb.com> wrote: > On Tue, Mar 21, 2017 at 8:16 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: >> Sure, I was telling you based on that. If you are implicitly treating >> it as 2-dimensional array, it might be easier to compute the array >>offsets. > > I think calculating spares offset will not become anyway much simpler > we still need to calculate split group and split phase separately. I > have added a patch to show how a 2-dimensional spares code looks like > and where all we need changes. >

I think one-dimensional patch has fewer places to touch, so that looks better to me. However, I think there is still hard coding and assumptions in code which we should try to improve. 1. + /* + * The first 4 bucket belongs to first splitpoint group 0. And since group + * 0 have 4 = 2^2 buckets, we double them in group 1. So total buckets + * after group 1 is 8 = 2^3. Then again at group 2 we add another 2^3 + * buckets to double the total number of buckets, which will become 2^4. I + * think by this time we can see a pattern which say if num_bucket > 4 + * splitpoint group = log2(num_bucket) - 2 + */ + if (num_bucket <= 4) + splitpoint_group = 0; /* converted to base 0. */ + else + splitpoint_group = _hash_log2(num_bucket) - 2; This patch defines split point group zero has four buckets and based on that above calculation is done. I feel you can define it like #define Buckets_First_Split_Group 4 and then use it in above code. Also, in else part number 2 looks awkward, can we define it as log2_buckets_first_group = _hash_log2(Buckets_First_Split_Group) or some thing like that. I think that way code will look neat. I don't like the way above comment is worded even though it is helpful to understand the calculation. If you want, then you can add such a comment in file header, here it looks out of place. 2. +power-of-2 groups, called "split points" in the code. That means on every new +split points we double the existing number of buckets. split points/split point 3. + * which phase of allocation the bucket_num belogs to with in the group. /belogs/belongs I have still not completely reviewed the patch as I have ran out of time for today. -- With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers