| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | Aidan Van Dyk <aidan(at)highrise(dot)ca>, Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov>, drkp(at)csail(dot)mit(dot)edu, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: SSI predicate locking on heap -- tuple or row? |
| Date: | 2011-05-23 14:36:23 |
| Message-ID: | BANLkTiknh-QyVOU9NXeR+mrj_+oR4UqcUQ@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Mon, May 23, 2011 at 10:20 AM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> Aidan Van Dyk <aidan(at)highrise(dot)ca> writes:
>> So, if SSI conflicts something on the UPDATE case, it would necessrily
>> have to conflict the DELETE+INSERT case as well, and vice-versa.
>
> This argument is fundamentally bogus, because an UPDATE is not the same
> thing as DELETE followed by INSERT. In the former case the new tuple
> will have a ctid link from the old one; in the latter case not. And
> that will affect the behavior of subsequent operations.
Right. The point I was driving at is - in what way will that affect
the behavior of subsequent operations?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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