tid scan - is it ever used?
I realize this might be "hackers" question, but I was wondering if anyone
has ever seen a "tid scan" in a query plan?
I think a tid scan would only be used if you did something like:
select ctid from mytable;
are there any other uses for a tid scan?
-- Thanks, Murphy
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murphy pope wrote:
I realize this might be "hackers" question, but I was wondering if anyone
has ever seen a "tid scan" in a query plan?I think a tid scan would only be used if you did something like:
select ctid from mytable;
AFAIK the tidscan is used when one specifies "WHERE ctid =
...".
are there any other uses for a tid scan?
Currently it is the fastest possible access to a single row.
So an application that selects data and wants to update rows
is optimized for PostgreSQL if it knows about that fact and
qualifies the updates by ctid.
I thought about getting ctid as a junk attribute when doing a
SELECT ... FOR UPDATE in a cursor and using that information
in UPDATE ... WHERE CURRENT OF <cursorname>.
Jan
--
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hi,
i am trying to remove a column from a table, but i have not been successful
yet...
can anyone help me?
sorry if it is too simple, but i'm a new user and there was nothing to help me
in the guides i have read.
thanks,
Fabricio
On Thu, 6 Jun 2002 15:39:11 -0300
"Fabricio Boppre" <fabricio@gprog.com.br> wrote:
i am trying to remove a column from a table, but i have not been successful
yet...
http://www.ca.postgresql.org/docs/faq-english.html#4.4
Cheers,
Neil
--
Neil Conway <neilconway@rogers.com>
PGP Key ID: DB3C29FC
"NC" == Neil Conway <nconway@klamath.dyndns.org> writes:
NC> On Thu, 6 Jun 2002 15:39:11 -0300
NC> "Fabricio Boppre" <fabricio@gprog.com.br> wrote:
i am trying to remove a column from a table, but i have not been successful
yet...
NC> http://www.ca.postgresql.org/docs/faq-english.html#4.4
Which is useless if you have foreign keys referencing your table.
--
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