| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Noah Misch <noah(at)leadboat(dot)com> |
| Cc: | Alvaro Herrera <alvherre(at)commandprompt(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: foreign key locks, 2nd attempt |
| Date: | 2012-03-13 17:09:57 |
| Message-ID: | CA+TgmoYA4HdOTm-w7g73=NYXC4m5SYJMYtxazO67aKWOHOxv3g@mail.gmail.com |
| Views: | Raw Message | Whole Thread | Download mbox | Resend email |
| Thread: | |
| Lists: | pgsql-hackers |
On Mon, Mar 12, 2012 at 9:24 PM, Noah Misch <noah(at)leadboat(dot)com> wrote:
> When we lock an update-in-progress row, we walk the t_ctid chain and lock all
> descendant tuples. They may all have uncommitted xmins. This is essential to
> ensure that the final outcome of the updating transaction does not affect
> whether the locking transaction has its KEY SHARE lock. Similarly, when we
> update a previously-locked tuple, we copy any locks (always KEY SHARE locks)
> to the new version. That new tuple is both uncommitted and has locks, and we
> cannot easily sacrifice either property. Do you see a way to extend your
> scheme to cover these needs?
No, I think that sinks it. Good analysis.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
| From | Date | Subject | |
|---|---|---|---|
| Next Message | Bruce Momjian | 2012-03-13 17:26:04 | Re: Website stylesheet for local docs |
| Previous Message | Bruce Momjian | 2012-03-13 17:00:52 | Re: foreign key locks, 2nd attempt |