Hi all,
looking at how ctid is used is clear to me:


insert line (A) in a table;      ==> ctid = (0, 1);
rollback an update for the line (A);
insert a line (B) in the table;  ==> ctid = (0, 3);
vacuum full;
insert a line (C) in the table;  ==> ctid = (0, 2);

I was expecting this for a normal vacuum not for a vacuum full.

for a vacuum full I was expecting:

insert line (A) in a table;      ==> ctid = (0, 1);
rollback an update for the line (A);
insert a line (B) in the table;  ==> ctid = (0, 3);
vacuum full; ( line B moved in ctid ( 0, 2) )
insert a line (C) in the table;  ==> ctid = (0, 3);


could this due the fact that moving that tuple will not
save any storage space ?

If not, am I missing something ?



Regards
Gaetano Mendola
















Tue, 17 Aug 2004 15:43:38 +0200
Gaetano Mendola <mendola@bigfoot.com>
vacuums  and  ctid
Gaetano Mendola <mendola@bigfoot.com> writes:
> could this due the fact that moving that tuple will not
> save any storage space ?

Yup.  VACUUM FULL is not interested in collapsing out unused CTID slots.

			regards, tom lane

Tue, 17 Aug 2004 11:05:49 -0400
Tom Lane <tgl@sss.pgh.pa.us>
Re: vacuums and ctid 