| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Kevin Grittner <Kevin(dot)Grittner(at)wicourts(dot)gov> |
| Cc: | Markus Wanner <markus(at)bluegap(dot)ch>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: determine snapshot after obtaining locks for first statement |
| Date: | 2009-12-17 15:06:50 |
| Message-ID: | 603c8f070912170706o57161394ie68f672c4da09bf6@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Dec 17, 2009 at 10:05 AM, Kevin Grittner
<Kevin(dot)Grittner(at)wicourts(dot)gov> wrote:
> "Markus Wanner" <markus(at)bluegap(dot)ch> wrote:
>
>> Another line of thought: isn't this like READ COMMITTED for just
>> the first operation in a SERIALIZABLE transaction?
>
> I've mulled it over and I have two different logical proofs that
> this is safe; if anyone is dubious I'd be happy to share.
>
> This seems likely to be of significant benefit in some workloads,
> and I can't see anywhere that it is likely to cost much. Any
> objections to adding this to the TODO list as a performance item?
I thought you concluded two emails ago that it wouldn't work for PG?
It's certainly not clear to me what exactly the TODO would be.
...Robert
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