Re: hamsterdb Transactional Storage (thanks to all of you)

From: <>
Date: Sun, 2 Aug 2009 00:41:52 -0700 (PDT)
Message-ID: <>

On Jul 31, 7:10 am, Christoph Rupp <> wrote:
> On Jul 22, 1:21 pm, wrote:
> > you still don't understand the basic concepts.
> feel free to explain them to me.

In my previous message I meant to bear bad tidings, but I didn't mean to have an attitude.

To expand on my previous message:
1. You have locks.
"Locking" just means others' access is constrained. Latches and mutexes are locks.
2. A system only has concurrency if each user's sequence of transactions proceeds despite other transactions. Isolation level is one way to define the kind of atomic changes that a transaction is a sequence of from the user's point of view.
(You don't seem to understand that isolation levels other than serializable violate ACID, unless you interpret the atomic changes as nested transactions.)
The system must produce some interleaving of these atomic changes.
Rollback and commitment are implementation concepts dealing with (user-invisible) attempted executions of individual transactions or atomic changes.
Each user must see their transactions advance (observing also non-deterministic atomic changes from other transactions between their own atomic changes).

I said these are basic concepts. If I haven't motivated you to re-examine some basic expositions, so be it.

philip Received on Sun Aug 02 2009 - 09:41:52 CEST

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