[Zope] RE: ZODBC problem (and ZmxODBC)

[Capesius, Alan]

Excellent. The ZmxODBC driver has resolved the problem for me.
Performance is now unaffected by the slow queries.

I'm using Access and SQL7 dbs, not sure if Access ODBC is multi-threaded, so
I may need to run a mix of drivers, but the test server hasn't crashed yet.

A note on the ZmxODBC install, the docs indicate that you should copy the mx
folder to the Shared folder. This will not work (and is the default). The
coding requires that you move the mx folder up one level after extraction it
into the Zope tree. It should be at ZopePath\lib\python\mx

Thanks Bryan,

Alan


>>>-----Original Message-----
>>>From: Bryan Baszczewski [mailto:bryanbz@2s2i.com]
>>>Sent: Wednesday, March 07, 2001 1:08 PM 
>>>To: 'Capesius, Alan'; zope@zope.org
>>>Cc: zope-dev@zope.org
>>>Subject: RE: [Zope-dev] RE: ZODBC problem
>>>
>>>
>>>Alan, I am having a similar lock-out problem while 
>>>performing a complex
>>>query on SQL Server 2K.  All other hits cannot connect until 
>>>the query
>>>returns the results.  My research has so far taken me here:
>>>
>>>http://www.zope.org/Members/petrilli/DARoadmap
>>>Which is telling me I am probably using at most a Level-2 DA 
>>>with my ZODBC.
>>>
>>>And then here:
>>>
>>>http://www.zope.org/Members/djay/ZmxODBC/ZmxODBC_0_0_2.tgz/README
>>>Which is a Level-3 mxZODBC DA (multithreaded).
>>>
>>>If anyone sees a problem with what I am about to do, let me 
>>>know.  What do
>>>you think?
>>>
>>>
>>>
>>>-----Original Message-----
>>>From: zope-dev-admin@zope.org 
>>>[mailto:zope-dev-admin@zope.org]On Behalf
>>>Of Capesius, Alan
>>>Sent: Wednesday, March 07, 2001 12:31 PM
>>>To: zope@zope.org
>>>Cc: zope-dev@zope.org
>>>Subject: [Zope-dev] RE: ZODBC problem
>>>
>>>
>>>Thanks Dieter, I was kinda looking for a solution, I 
>>>reviewed the mailing
>>>lists but do not see any solutions. I've done some more testing here:
>>>
>>>Summary: The user selects an involved financial report. The 
>>>report takes
>>>about 55 seconds for Zope to prepare. The first second is 
>>>the SQL server
>>>request and reply. The remaining time is Zope processing 
>>>(dual 200mhz NT
>>>box).
>>>
>>>My queries are SELECT JOINS. No tables are modified at the server.
>>>
>>>The problem I see here is that Zope/ZODBCDA is holding the 
>>>connection to SQL
>>>open via ODBC until all processing is complete and then 
>>>issuing an SQL
>>>statement:  IF @@TRANCOUNT>0 COMMIT TRAN
>>>
>>>Zope could free up this connection after one second. (at 
>>>least in this case)
>>>Until Zope does the commit, other users are locked out.
>>>
>>>For read only queries, there is no need to have the request under
>>>transaction control. In any case, Zope should be able to 
>>>early release the
>>>SQL connection and then process on the results.
>>>
>>>Certainly increasing processor speed will mask this problem 
>>>and provide
>>>better response to users, but I'm hoping for a real fix.
>>>
>>>Thanks,
>>>Alan
>>>
>>>Network Monitor trace  Wed 03/07/01 10:51:50  c:\cap1.TXT
>>>
>>>Frame   Time    Src MAC Addr   Dst MAC Addr   Protocol
>>>1       4.413   006008F6062B   COMPAQ851F04   TCP
>>>2       4.413   006008F6062B   COMPAQ851F04   TCP
>>>3       4.413   006008F6062B   COMPAQ851F04   TCP
>>>[....]
>>>193     5.072   006008F6062B   COMPAQ851F04   TCP
>>>194     5.073   COMPAQ851F04   006008F6062B   TCP
>>>195     5.090   COMPAQ851F04   006008F6062B   TCP
>>>196     5.090   006008F6062B   COMPAQ851F04   TCP
>>>197     5.090   006008F6062B   COMPAQ851F04   TCP
>>>198     5.091   COMPAQ851F04   006008F6062B   TCP
>>>199     5.109   COMPAQ851F04   006008F6062B   TCP
>>>200     5.127   COMPAQ851F04   006008F6062B   TCP // SQL 
>>>server goes idle
>>>after this
>>>
>>>// python DTML processing occurs here
>>>
>>>
>>>201     10.834  006008F6062B   COMPAQ851F04   TCP // not 
>>>sure what this is,
>>>Data is 0xA8
>>>202     10.834  COMPAQ851F04   006008F6062B   TCP // reply, 
>>>data is empty
>>>
>>>// page returns to user at 60 second mark
>>>// then Zope closes the connection
>>>203     60.385  COMPAQ851F04   006008F6062B   TCP
>>>        SQL: IF @@TRANCOUNT>0 COMMIT TRAN
>>>204     60.386  006008F6062B   COMPAQ851F04   TCP
>>>205     60.601  COMPAQ851F04   006008F6062B   TCP
>>>
>>>
>>>>Capesius, Alan writes:
>>>> > ...
>>>> > with further testing I
>>>> > have determined that the Zope server itself is not 
>>>locking up, but
>>>rather
>>>> > requests to the database (MS SQL7 via ZODBCDA) seem to 
>>>be queueing up.
>>>
>>>>My memory tells me faintly that such an issue has already been
>>>>discussed in the mailing lists (zope, zope-dev).
>>>>When I remember right, ZODBCDA synchronizes all database requests
>>>>--> searchable list archives...
>>>
>>>
>>>>Dieter
>>>
>>>_______________________________________________
>>>Zope-Dev maillist  -  Zope-Dev@zope.org
>>>http://lists.zope.org/mailman/listinfo/zope-dev
>>>**  No cross posts or HTML encoding!  **
>>>(Related lists -
>>> http://lists.zope.org/mailman/listinfo/zope-announce
>>> http://lists.zope.org/mailman/listinfo/zope )
>>>