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Re: [Gnumed-devel] one method of allowing clients to re-start.


From: Karsten Hilbert
Subject: Re: [Gnumed-devel] one method of allowing clients to re-start.
Date: Mon, 24 Feb 2003 10:04:58 +0100
User-agent: Mutt/1.3.22.1i

> The pessimistic approach is single write locking. 
> Scenario is :
> 1. one doctor opens a patient record, and gets a timestamped write lock.
It shouldn't, with PostgreSQL.

> 2. another doctor tries to edit the same record and detects an active
> write lock and is denied access.
MVCC

> 5. another doctor which tries to access a record with a questionable
> write lock is asked whether he should override the write lock. If yes,
> then the write locked is lost.
This is not available server-side and would thus have to be
implemented on the client. Which is undesirable, particularly
for locks.

> 6. The original writing doctor re-starts his client, which immediately
> checks it still has write lock; because it has been retired, the client
> regrettfully informs the doctor his session was lost.
The restarted client would have to save elaborate connection
state information to make sure it is working against the same
set of databases as last time around.

I don't see this scenario happen in real life.

Karsten
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