Обсуждение: Re: AW: AW: BLERe: AW: AW: relation ### modified while in use

At 09:36 25/10/00 +0200, Zeugswetter Andreas SB wrote:
>
>> I have not followed the entire thread, but if you are in a serializable OR
>> repeatable-read transaction,
>
>Serializable and repeatable read are the same thing, different wording.

Not last time I looked. RR ensures that rows you have seen will still
return the same data, but allows a reexecuted cursor to return more rows.
Serializable means cursors always return expected data the second time they
are executed.


>> I would think that read-only statements will
>> need to keep some kind of lock on the rows they read (or the table).
>
>Yes, we were talking about the other isolation levels. Most,
>but not all of my mails in this thread state this difference.

The bit that worried me was that most emails only referred to serializable,
not RR (which they should have, I think).


----------------------------------------------------------------
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Albatross Consulting Pty. Ltd.   |----/       -  \
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Philip Warner wrote:

> At 09:36 25/10/00 +0200, Zeugswetter Andreas SB wrote:
> >
> >> I have not followed the entire thread, but if you are in a serializable OR
> >> repeatable-read transaction,
> >
> >Serializable and repeatable read are the same thing, different wording.
>
> Not last time I looked. RR ensures that rows you have seen will still
> return the same data, but allows a reexecuted cursor to return more rows.
> Serializable means cursors always return expected data the second time they
> are executed.
>

Currently PostgreSQL doesn't support REPEATABLE READ isolation level.
But we could use SERIALIZABLE isolation level instead of RR isolaiton level
because SERIALIZABLE isolation level satisfies the condition of RR isolation
level(as you mentioned above).

>
> >> I would think that read-only statements will
> >> need to keep some kind of lock on the rows they read (or the table).
> >
> >Yes, we were talking about the other isolation levels. Most,
> >but not all of my mails in this thread state this difference.
>
> The bit that worried me was that most emails only referred to serializable,
> not RR (which they should have, I think).
>
> ----------------------------------------------------------------
> Philip Warner                    |     __---_____
> Albatross Consulting Pty. Ltd.   |----/       -  \
> (A.B.N. 75 008 659 498)          |          /(@)   ______---_
> Tel: (+61) 0500 83 82 81         |                 _________  \
> Fax: (+61) 0500 83 82 82         |                 ___________ |
> Http://www.rhyme.com.au          |                /           \|
>                                  |    --________--
> PGP key available upon request,  |  /
> and from pgp5.ai.mit.edu:11371   |/