In article <20100308213549.gb...@svana.org>, Martijn van Oosterhout <klep...@svana.org> writes:
>> "subsequent ... will store a null value" would imply that deleted columns >> will still take some place, while "the space will be reclaimed ..." would >> suggest that new rows (insert or updates in mvcc) don't have the deleted >> column anymore - I'm not quite sure how to interpret this. What is pg >> doing? > What you're missing is that in postgres NULLs are stored as a bit in > the header and there is no data. So in a sense NULLs take no space > (well, one bit) which means both statements are true. But if you already have eight nullable columns, the (maybe originally non-null) column which has been dropped would cause the header to be one byte larger, wouldn't it? -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
