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Uniquness of ctid 2+ messages / 2 participants [nested] [flat]
* Uniquness of ctid @ 2023-07-19 17:21 PG Doc comments form <noreply@postgresql.org> 2023-07-19 21:39 ` Re: Uniquness of ctid David G. Johnston <david.g.johnston@gmail.com> 0 siblings, 1 reply; 2+ messages in thread From: PG Doc comments form @ 2023-07-19 17:21 UTC (permalink / raw) To: pgsql-docs@lists.postgresql.org; +Cc: heonieb@gmail.com The following documentation comment has been logged on the website: Page: https://www.postgresql.org/docs/15/ddl-system-columns.html Description: Hi, Looking at the explanation abour ctid, it is "The physical location of the row version within its table. " From that line, I think ctid is unique in the table. And I also think ctid might be unique across the database since it is the physical location. But I was not sure about this. Please confirm if my assumption is right or not. Thanks Brian ^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: Uniquness of ctid 2023-07-19 17:21 Uniquness of ctid PG Doc comments form <noreply@postgresql.org> @ 2023-07-19 21:39 ` David G. Johnston <david.g.johnston@gmail.com> 0 siblings, 0 replies; 2+ messages in thread From: David G. Johnston @ 2023-07-19 21:39 UTC (permalink / raw) To: heonieb@gmail.com; pgsql-docs@lists.postgresql.org On Wed, Jul 19, 2023 at 2:31 PM PG Doc comments form <noreply@postgresql.org> wrote: > The following documentation comment has been logged on the website: > > Page: https://www.postgresql.org/docs/15/ddl-system-columns.html > Description: > > Hi, > Looking at the explanation abour ctid, it is "The physical location of the > row version within its table. " > From that line, I think ctid is unique in the table. > Unique but not stable - if you give your actual record an ID value the associated ctid for it may very well change over time and a given ctid can be associated with any number of IDs > And I also think ctid might be unique across the database since it is the > physical location. > The concept doesn't even apply - the value itself only makes sense within a given physical table. i.e., the table is implied. It's like saying "I live at 123 Main St." to someone. Sure in any given place there can only be a single 123 Main St. but that really isn't useful by itself. And to extend back to the previous point, you may live there now but you will likely have a different address in the future and someone else will have 123 Main St. David J. ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2023-07-19 21:39 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2023-07-19 17:21 Uniquness of ctid PG Doc comments form <noreply@postgresql.org> 2023-07-19 21:39 ` David G. Johnston <david.g.johnston@gmail.com>
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