On 20 December 2012 14:56, Amit Kapila <amit.kap...@huawei.com> wrote:
>> > 1. There is no performance change for cloumns that have all valid >> > values(non- NULLs). I don't see any tests (at all) that measure this. I'm particularly interested in lower numbers of columns, so we can show no regression for the common case. >> > 2. There is a visible performance increase when number of columns >> containing >> > NULLS are more than > 60~70% in table have large number of columns. >> > >> > 3. There are visible space savings when number of columns containing >> NULLS >> > are more than > 60~70% in table have large number of columns. Agreed. I would call that quite disappointing though and was expecting better. Are we sure the patch works and the tests are correct? The lack of any space saving for lower % values is strange and somewhat worrying. There should be a 36? byte saving for 300 null columns in an 800 column table - how does that not show up at all? -- Simon Riggs http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
