[Zope-DB] SQL Relay and _v_ variables

Robert Kellock sales at creditscore.co.nz
Fri Oct 24 04:48:00 EDT 2003


I have never used SQLRelay with Zope, but I have used something that works in a very similar way - isectZope (http://www.creditscore.co.nz/node7.html). The main difference between SQLRelay and isectZope is that SQLRelay is Unix only.  isectZope runs on Unix and Windows.  isectZope has a feature that might be of interest to the long running thread on DCOracle2 leaking connections. Like SQLRelay, at startup isectZope invokes a number of persistent database daemons which it then allocates client requests to from a queue. ZisectZDA connects to isectZope by simply opening a socket - an extremely lightweight process. I haven't looked closely at SQLRelay's code, but I would imagine it is doing something similar. However, SQLRelay doesn't appear to have a mechanism for restarting daemons that have spontaneously dropped.  isectZope detects whenever a daemon has died and restarts it. The downside to isectZope is that the only daemon available for it is Interbase/Firebird :-(
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On 23/10/03 at 18:43 Chris Withers wrote:

>Andreas Kaiser wrote:
>> It comes with it´s own DA: ZSQLRelayDA.
>Interesting to note that this DA doesn't use _v_ variables.
>It opens a connection at the beginning of the transaction and closes when
>transaction is finalised or aborted.
>This mirrors the pathalogical ZOracleDA case, except that it doesn't leak 
>connections as far as anyone has commented ;-)
>I'm guessing the constant opening/closing of connections is slower than
>them around, but maybe not as slow as it would be, since by the looks of
>it, SQL 
>Relay will live on the web server, and should be designed to be quick and 
>lightweight to connect to.
>Can anyone confirm this?
>Who's using SQL Relay under high load with lots of database adapters in
>Zope-DB mailing list
>Zope-DB at zope.org

Robert Kellock
Sales Manager
Credit Systems Control Ltd
Ph: 64 3 3266115

'making decisions easy'

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