| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Hannu Krosing <hannu(at)krosing(dot)net> |
| Cc: | Jim Nasby <jim(at)nasby(dot)net>, Simon Riggs <simon(at)2ndquadrant(dot)com>, Christopher Browne <cbbrowne(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: Future In-Core Replication |
| Date: | 2012-05-04 13:01:28 |
| Message-ID: | CA+TgmoYCC37GHcA0-0cKwiLGvBY7e0AbgVfY52o756A-VVdX-g@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, May 4, 2012 at 8:32 AM, Hannu Krosing <hannu(at)krosing(dot)net> wrote:
> For logical we don't really need to uniquely identify such rows - it
> should sufficient if we just update exactly one of the matching rows.
>
> The way to do this is to put all fields of the OLD.* tuple in the WHERE
> clause and then update just one matching row.
>
> IIRC updating (or deleting) CURRENT OF a cursor is currently supported
> only in pl/pgsql so this needs to be done using a plpgsql cursor.
>
> If the table has no indexes or index lookup returns lots of rows, then
> this is bound to be slow, but in this case it was probably slow on
> master too :)
I was about to write a reply saying exactly this, but you said it
better than I would have been able to manage.
I think this is all exactly right.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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