Re: incoherent view of serializable transactions - Mailing list pgsql-hackers

From Kevin Grittner
Subject Re: incoherent view of serializable transactions
Date
Msg-id 4961CA11.EE98.0025.0@wicourts.gov
Whole thread Raw
In response to Re: incoherent view of serializable transactions  (Peter Eisentraut <peter_e@gmx.net>)
Responses Re: incoherent view of serializable transactions  (Peter Eisentraut <peter_e@gmx.net>)
List pgsql-hackers
>>> Peter Eisentraut <peter_e@gmx.net> wrote:
> A language lawyer might also point out that the note that contains 
> the "explicitness" isn't actually part of the formal standard.  The
only 
> thing that the standard formally defines are the excluded phenomena.
Previously quoted, from the standard:
"The execution of concurrent SQL-transactions at isolation level
SERIALIZABLE is guaranteed to be serializable. A serializable
execution is defined to be an execution of the operations of
concurrently executing SQL-transactions that produces the same
effect as some serial execution of those same SQL-transactions. A
serial execution is one in which each SQL-transaction executes to
completion before the next SQL-transaction begins."
> More to the point, think about how a user might want to think about
these 
> issues.
> 
> "The standard also requires that serializable transactions behave as
though 
> [...]" --- User: The standard requires it, but is it also
implemented?  
> (Apparently not, but that is explained somewhere else.)
That's something I thought about, but failed to find a good way to
incorporate at that point, and I thought the discussion in the
following sections covered it.  Perhaps a reference to those following
sections at the point of definition?
> "is a natural consequence of the fact" --- There is nothing natural
> about any of this.  Why is it a consequence and how?
How could you possibly get any of those phenomena if there are no
concurrent transactions?
-Kevin


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