That is a very awesome system. I am constantly impressed at the awesomeness of Postgresql. Alex On Feb 4, 2008 1:06 PM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > Jorge Godoy <jgodoy@xxxxxxxxx> writes: > > Em Monday 04 February 2008 07:03:47 Dawid Kuroczko escreveu: > >> Well, but PostgreSQL's NULLs occupy almost no space, or rather a bit of > >> space, that is one bit exactly. ;-) I am pretty much sure that > >> storage-wise looking NULLs > >> are more efficient. > > > I'd say 1 byte every 8 NULLs instead of 1 bit. If you only have 1 NULL, it > > will cost you 1 byte (not 1 bit). If you have 9, it will cost you 2 bytes > > (not 9 bits). > > This is not quite right --- the amount of space used doesn't change if > you have more or fewer nulls in a row. A null bitmap is present in a > row if there are any nulls at all in the row, and its size will be equal > to the defined number of columns in the table. As you say, there's > padding overhead too ... > > regards, tom lane > > > ---------------------------(end of broadcast)--------------------------- > TIP 4: Have you searched our list archives? > > http://archives.postgresql.org/ > ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
