August 1999 - Zope - Zope lists

Cannot add a Z SQL method - 2
by Constantin Teodorescu 10 Aug '99

10 Aug '99

Oups, forgot to mention! Adding a "Z Gadfly Database connection" connected to "demo" database performs the same. Trying to add a "Z SQL method" is not allowed. Best regards, -- Constantin Teodorescu FLEX Consulting Braila, ROMANIA

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ZODB corruption? WWYD?
by Thaxter, Jason M. 10 Aug '99

10 Aug '99

I had a problem removing an item from a folder: Zope has encountered an error while publishing this resource. exceptions.AttributeError Sorry, a Zope error occurred. Traceback (innermost last): File /zope/Zope-2.0.0b1-src/lib/python/ZPublisher/Publish.py, line 256, in publish_module File /zope/Zope-2.0.0b1-src/lib/python/ZPublisher/Publish.py, line 161, in publish File /zope/Zope-2.0.0b1-src/lib/python/ZPublisher/mapply.py, line 154, in mapply (Object: manage_delObjects) File /zope/Zope-2.0.0b1-src/lib/python/ZPublisher/Publish.py, line 98, in call_object (Object: manage_delObjects) File /zope/Zope-2.0.0b1-src/lib/python/OFS/ObjectManager.py, line 392, in manage_delObjects (Object: ElementWithAttributes) File /zope/Zope-2.0.0b1-src/lib/python/OFS/ObjectManager.py, line 264, in _delObject (Object: ElementWithAttributes) File /zope/Zope-2.0.0b1-src/lib/python/Products/OFSP/Draft.py, line 218, in manage_beforeDelete (Object: AddocPart) File /zope/Zope-2.0.0b1-src/lib/python/Products/OFSP/Draft.py, line 174, in nonempty (Object: AddocPart) AttributeError: VersionBase I tried bbb.py to see what's up: machine$ python utilities/bbb.py var/Data.fs Corrupted data record at 9 Are there tools available for fixing this? Of course, this is only a test site, so I don't really care if I lose data, but would I normally expect to lose all data following this record? I assume that data loss could be minimized by exporting useful objects and re-importing them, but I need to know if this is the right fix before beginning to use anything "for real". JT

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RE: [Zope] Database Connections for ZOPE 1.10.3
by Marten Quadland 10 Aug '99

10 Aug '99

Jim, Regarding the indefinite block on data due to multiple requests on the same table, I have two questions: 1) Does it matter if the Database connection is on two different Machines or on machine? 2) Where does this problem occur, the single threaded ODBC connection, Oracle, Zope, or where? If I understand Oracle correctly, as soon as the insert on T1 has been commited, then the lock will be released on the page and the select from the T2 query should run without a problem. Quad -----Original Message----- From: Jim Fulton [mailto:jim@digicool.com] Sent: Tuesday, August 10, 1999 8:07 AM To: Theodore Patrick Cc: 'zope(a)zope.org' Subject: Re: [Zope] Database Connections for ZOPE 1.10.3 Theodore Patrick wrote: > > ZOPE 1.10.3 > > I have two separate database connections to an oracle database. The > connections are in separate folders and are attached to the same ORACLE > database. > > Are there any hidden do's and don'ts for multiple database connections? The transaction machinery in Oracle, or any database that supports transactions can lead to a deadlock situation if you have multiple connections to the same database. For example, suppose you have - Connections C1 and C2 to database D, - SQL method S1 using C1: insert into data values (...) - SQL method S2 using C2: select * from data - In a web request, you invoke a method (e.g. a DTMLMethod or an ExternalMethod) that calls S1 and then calls S2. Because S1 and S2 use separate Oracle connections, they participate in separate Oracle transactions. Let's call these transactions T1 and T2. The operation done by S1 in T1 will lock (at least some part of) the data table until T1 completes. The operation done by S2 in T2 must block, since it's result would be affected by the completion, or non-completion of T1. Therefore, the thread executing the request will block indefinately waiting for T1 to complete. This makes using multiple connections to the same database in the same request rather unattractive. :) > Are the connections actually one in the same? No. > Are there any platform issues where this is a bad idea(Windows ODBC or LINUX > - NET8)? I don't know if there are any additional platform issues. Jim -- Jim Fulton mailto:jim@digicool.com Python Powered! Technical Director (888) 344-4332 http://www.python.org Digital Creations http://www.digicool.com http://www.zope.org Under US Code Title 47, Sec.227(b)(1)(C), Sec.227(a)(2)(B) This email address may not be added to any commercial mail list with out my permission. Violation of my privacy with advertising or SPAM will result in a suit for a MINIMUM of $500 damages/incident, $1500 for repeats. _______________________________________________ Zope maillist - Zope(a)zope.org http://www.zope.org/mailman/listinfo/zope (To receive general Zope announcements, see: http://www.zope.org/mailman/listinfo/zope-announce For developer-specific issues, zope-dev(a)zope.org - http://www.zope.org/mailman/listinfo/zope-dev )

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pooling database connections
by Jason Jones 10 Aug '99

10 Aug '99

As I understand it, an SQL DB connection is only a single instance of the connection, and while I can create other instances with the same id in subfolders, I can't at the top level. For a multithreaded database adaptor, I guess this isn't a problem, but what about a level 1 or 2 adaptor like the MySQL adaptor? Is there some way that I can create several instances of a database connection at the root level (pool connections, not connections with separate ids) so that SQL methods anywhere in the heirarchy can grab whichever one is available? Does zope do this by default and I'm just not aware of it? If so, what are the defaults and how can I change them? It seems like this would be an easy way to improve database performance, but i didn't see it in the docs. Also, how long is an inactive connection maintained, and is there any way to prevent the connection from closing? Thanks, Jason Jones jason_j(a)countermedia.org

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Counter for Visitors
by Stephan Richter 10 Aug '99

10 Aug '99

I want to put a little counter on my page. Currently I have the following. Please tell me how good that is: I declared a property called visitors (integer); I wrote a external method that increases the value of the property: (Is the following code right?) def add_visitor(self): self.visitors = self.visitors + 1 And a display function: def show_visitors(self): return self.visitors Is there a way to do it with DTML only. I do not neccessarily write external methods, but that is the only solution I see. stephan -- Stephan Richter iXL - Software Designer and Engineer

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Load Balancing and OTS
by Stephan Richter 10 Aug '99

10 Aug '99

Just for my record, Does Zope support load balancing and/or OTS? Where can I find more information? A Java developer asked me about it. stephan -- Stephan Richter iXL - Software Designer and Engineer

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Sequence
by Anderson Ami 10 Aug '99

10 Aug '99

How i work with sequences ? anderson ______________________________________________________ Get Your Private, Free Email at http://www.hotmail.com

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Re: [Zope] pcgi info file error
by Anthony Baxter 10 Aug '99

10 Aug '99

>>> Joshua Brauer wrote > What I found to be the answer: > > Install Python 1.5.2 on your machine AND remove Python 1.5.1 (if it's > in your path). There seems to be a number of posts recently with problems from vendors distribution of versions of Python that are either pre-1.5.2 or not compiled with thread support Can people who were bitten by this make sure they let whoever provided their distribution know that they should provide a 1.5.2 with threading? (last I looked, RH6.0 doesn't ship with --with-thread... :(

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Cannot add a Z SQL method
by Constantin Teodorescu 10 Aug '99

10 Aug '99

Hi! It's me again :-) with another problem Environment: -Linux RedHat 5.2 i386 on K6-350 -upgraded to python 1.5.2 (rpm) -got Zope 2.0.0b3 and installed it -got ZPyGreSQL 0.03 and updated it with PyGreSQL 2.4 from the last PostgreSQL 6.5.1 distribution compiled from scratch install was ok I choose to use ZServer chown nobody to var directory ran ./start as root user I am using Netscape 4.61 on the same computer where Zope runs (cache option verify every time) and where PostgreSQL server runs. Zope appears to work fine, in management screens , Control Panel I can see the ZPyGreSQLDA product installed, appears to be just fine! I am adding a Z PyGreSQL Database connection, I can open/close the database, no problem. I am trying to add a Z SQL methods. It says : Warning: There are no SQL database connections. You need to add a Zope SQL database connection before you can use a Zope SQL Method. ?!?!? I was playing last week a couple of days with 1.10 version with PostgreSQL (6.5.1) and everything was ok. Done queryies, reports, search forms. Am I doing something wrong? Best regards, -- Constantin Teodorescu FLEX Consulting Braila, ROMANIA

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FW: [Zope] Database Connections for ZOPE 1.10.3
by Marten Quadland 10 Aug '99

10 Aug '99

Jim, Regarding the indefinite block on data due to multiple requests on the same table, I have two questions: 1) Does it matter if the Database connection is on two different Machines or on machine? 2) Where does this problem occur, the single threaded ODBC connection, Oracle, Zope, or where? If I understand Oracle correctly, as soon as the insert on T1 has been commited, then the lock will be released on the page and the select from the T2 query should run without a problem. Quad -----Original Message----- From: Jim Fulton [mailto:jim@digicool.com] Sent: Tuesday, August 10, 1999 8:07 AM To: Theodore Patrick Cc: 'zope(a)zope.org' Subject: Re: [Zope] Database Connections for ZOPE 1.10.3 Theodore Patrick wrote: > > ZOPE 1.10.3 > > I have two separate database connections to an oracle database. The > connections are in separate folders and are attached to the same ORACLE > database. > > Are there any hidden do's and don'ts for multiple database connections? The transaction machinery in Oracle, or any database that supports transactions can lead to a deadlock situation if you have multiple connections to the same database. For example, suppose you have - Connections C1 and C2 to database D, - SQL method S1 using C1: insert into data values (...) - SQL method S2 using C2: select * from data - In a web request, you invoke a method (e.g. a DTMLMethod or an ExternalMethod) that calls S1 and then calls S2. Because S1 and S2 use separate Oracle connections, they participate in separate Oracle transactions. Let's call these transactions T1 and T2. The operation done by S1 in T1 will lock (at least some part of) the data table until T1 completes. The operation done by S2 in T2 must block, since it's result would be affected by the completion, or non-completion of T1. Therefore, the thread executing the request will block indefinately waiting for T1 to complete. This makes using multiple connections to the same database in the same request rather unattractive. :) > Are the connections actually one in the same? No. > Are there any platform issues where this is a bad idea(Windows ODBC or LINUX > - NET8)? I don't know if there are any additional platform issues. Jim -- Jim Fulton mailto:jim@digicool.com Python Powered! Technical Director (888) 344-4332 http://www.python.org Digital Creations http://www.digicool.com http://www.zope.org Under US Code Title 47, Sec.227(b)(1)(C), Sec.227(a)(2)(B) This email address may not be added to any commercial mail list with out my permission. Violation of my privacy with advertising or SPAM will result in a suit for a MINIMUM of $500 damages/incident, $1500 for repeats. _______________________________________________ Zope maillist - Zope(a)zope.org http://www.zope.org/mailman/listinfo/zope (To receive general Zope announcements, see: http://www.zope.org/mailman/listinfo/zope-announce For developer-specific issues, zope-dev(a)zope.org - http://www.zope.org/mailman/listinfo/zope-dev )

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