It can save space because the line pointers have less alignment
requirements. But I don't see any point in the current state.
--
Greg
On 2009-12-04, at 3:48 PM, Tom Lane <t...@sss.pgh.pa.us> wrote:
Greg Stark <gsst...@mit.edu> writes:
I'm not sure why I said "including ctid". We would have to move
everything transactional to the line pointer, including xmin, xmax,
ctid, all the hint bits, the updated flags, hot flags, etc. The only
things left in the tuple header would be things that have to be there
such as HAS_OIDS, HAS_NULLS, natts, hoff, etc. It would be a pretty
drastic change, though a fairly logical one. I recall someone
actually
submitted a patch to separate out the transactional bits anyways a
while back, just to save a few bytes in in-memory tuples. If we could
save on disk-space usage it would be a lot more compelling. But it
doesn't look to me like it really saves enough often enough to be
worth so much code churn.
It would also break things for indexes, which don't need all that
stuff
in their line pointers.
More to the point, moving the same bits to someplace else on the page
doesn't save anything at all.
regards, tom lane
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
