Re: Documenting serializable vs snapshot isolation levels

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От Robert Haas
Тема Re: Documenting serializable vs snapshot isolation levels
Дата
Msg-id 603c8f070812291916tce34d2fqa56c442c7ea11e7c@mail.gmail.com
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Ответ на Re: Documenting serializable vs snapshot isolation levels  (Gregory Stark <stark@enterprisedb.com>)
Ответы Re: Documenting serializable vs snapshot isolation levels  ("Kevin Grittner" <Kevin.Grittner@wicourts.gov>)
Список pgsql-hackers
On Mon, Dec 29, 2008 at 9:28 PM, Gregory Stark <stark@enterprisedb.com> wrote:
> "Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
>> (3)  A finer-grained approach would be to make no-effect updates to
>> rows to lock them if they are to be read for purposes of updating
>> something else in the transaction.  This could have a high cost in
>> disk access and table bloat.  It has the advantage of providing a
>> simple technique which, if applied consistently, doesn't require
>> knowledge of software beyond what is under development.
>
> "no-effect updates" would be just the same as SELECT FOR UPDATE

...except that SELECT FOR UPDATE won't create table bloat, or as much
I/O... I think?

> However this has the same problem that we previously discussed where someone
> can still add new records which would have changed the results of the query.

...Robert


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