From mscott at springfieldtech.com  Thu Jun  1 14:48:53 2006
From: mscott at springfieldtech.com (Matthew Scott)
Date: Thu, 1 Jun 2006 07:48:53 -0500
Subject: [DB-SIG] [ANN] Schevo 2006 June Software Release
Message-ID: <9883CA12-4943-49D8-8C4B-491335ECAA72@springfieldtech.com>

===================================
Schevo 2006 June Software Release
===================================

Orbtech, L.L.C. and the Schevo team are pleased to announce the  
availability
of the 2006 June software release of Schevo and related support  
packages.

Details and installation information are available at:

   http://schevo.org/trac/wiki/SoftwareRelease-2006-06

General information about Schevo is available at:

   http://schevo.org/


Upgrades in this release
========================

* Schevo 3.0b2


New packages in this release
============================

* SchevoDot 1.0a1
* SchevoGears 1.0a1
* SchevoGtk 1.0a1
* SchevoSql 1.0a1
* SchevoWeb 1.0a1
* SchevoXml 1.0a1


What is Schevo
==============

Schevo is a next-generation DBMS that focuses on the following:

* **Rapid Development**: Schevo includes features to make it easy and  
fun to
   create even the most complex of databases. Not only is the schema  
syntax
   easy to write and understand, you can also quickly place initial  
values in
   your schema that are required by your database, and use the same  
syntax to
   create sets of sample data to use during development.

* **User Interface Generation**: Schevo provides user interface  
toolkits that
   take advantage of the richness of the database schema. You can use  
the
   full-featured Schevo Navigator to interact with your database without
   writing a single line of code outside of your database schema. A  
PyQt-based
   toolkit is already available, and PyGtk and TurboGears toolkits  
are in the
   works.

* **Rich Schema Definition**: The schema for a Schevo database is  
written in
   concise, easy-to-read Python code. Not only does the schema  
describe how
   information in the database is structured, but also defines all  
transactions
   and rules that ensure database integrity.

* **Automated Schema Evolution**: Once a Schevo database is deployed  
and is
   used to store valuable data, you will inevitably make further  
changes to the
   structure of the database. Schevo assists you in this task and  
makes it easy
   to restructure a database and facilitate the migration of data  
from one
   schema version to the next.

* **Transaction Based**: Schevo is designed from the ground up to  
protect your
   data. All changes to a Schevo database must be done using  
transactions, and
   Schevo ensures that those transactions always leave the database in a
   consistent state.

--
Matthew Scott
mscott at springfieldtech.com




From szybalski at gmail.com  Wed Jun  7 18:28:12 2006
From: szybalski at gmail.com (Lukasz Szybalski)
Date: Wed, 7 Jun 2006 11:28:12 -0500
Subject: [DB-SIG] [parameter substitution] how to escape perecent?
Message-ID: <804e5c70606070928g42cd749exa0d10a1b01ca2823@mail.gmail.com>

I am doing a parameter substitution, but when I execute the following
statement I get an error. Could you tell me how should i escape %
signs?

sql="select DATE_FORMAT(FROM_UNIXTIME(my_table.received_date),'%Y %M
%d,%H:%i') from my_table where my_table.from_email=%s"

then
c.execute(sql,('myemail at mydomain'))
or
c.execute(sql,(email))

I get an error :
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/lib/python2.3/site-packages/MySQLdb/cursors.py", line
137, in execute
    self.errorhandler(self, exc, value)
  File "/usr/lib/python2.3/site-packages/MySQLdb/connections.py", line
33, in defaulterrorhandler
    raise errorclass, errorvalue
ValueError: unsupported format character 'Y' (0x59) at index 59

Thank You
Lucas

From cdamundsen at gmail.com  Wed Jun  7 18:51:51 2006
From: cdamundsen at gmail.com (Craig Amundsen)
Date: Wed, 7 Jun 2006 09:51:51 -0700
Subject: [DB-SIG] [parameter substitution] how to escape perecent?
In-Reply-To: <804e5c70606070928g42cd749exa0d10a1b01ca2823@mail.gmail.com>
References: <804e5c70606070928g42cd749exa0d10a1b01ca2823@mail.gmail.com>
Message-ID: <8dc0c28f0606070951y7f641d9fq1cb17c7547081c09@mail.gmail.com>

Hi -

I am doing a parameter substitution, but when I execute the following
> statement I get an error. Could you tell me how should i escape %
> signs?
>
> sql="select DATE_FORMAT(FROM_UNIXTIME(my_table.received_date),'%Y %M
> %d,%H:%i') from my_table where my_table.from_email=%s"
>
> then
> c.execute(sql,('myemail at mydomain'))
> or
> c.execute(sql,(email))


>>> sql="select DATE_FORMAT(FROM_UNIXTIME(my_table.received_date),'%%Y %%M
%%d,%%H:%%i') from my_table where my_table.from_email=%s" % '
myaddress at mydomain.com'
>>> sql
"select DATE_FORMAT(FROM_UNIXTIME(my_table.received_date),'%Y %M %d,%H:%i')
from my_table where my_table.from_email=myaddress at mydomain.com"

- Craig
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From stuart at stuartbishop.net  Thu Jun 22 07:58:53 2006
From: stuart at stuartbishop.net (Stuart Bishop)
Date: Thu, 22 Jun 2006 12:58:53 +0700
Subject: [DB-SIG] Two phase commit API
Message-ID: <449A319D.5030903@stuartbishop.net>

Hi.

Are there any drivers out there that support two phase commit.

If so, what syntax do they use?

Is it worth adding a standard API for this as an optional extension to the
DB-API 2.0? Enough backends now support this that I suspect it is worth
doing this now to avoid unnecessary incompatibilities between backend
specific database APIs.

-- 
Stuart Bishop <stuart at stuartbishop.net>
http://www.stuartbishop.net/

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From mal at egenix.com  Thu Jun 22 09:37:47 2006
From: mal at egenix.com (M.-A. Lemburg)
Date: Thu, 22 Jun 2006 09:37:47 +0200
Subject: [DB-SIG] Two phase commit API
In-Reply-To: <449A319D.5030903@stuartbishop.net>
References: <449A319D.5030903@stuartbishop.net>
Message-ID: <449A48CB.1050501@egenix.com>

Stuart Bishop wrote:
> Hi.
> 
> Are there any drivers out there that support two phase commit.
> 
> If so, what syntax do they use?

I'm not aware of any native driver that does support this, except a
patched DCOracle2:

http://pymqi.sourceforge.net/

You can also use mxODBC with an XA enabled ODBC driver (I think
the EasySoft Oracle ODBC driver is capable of doing XA), but the
APIs for setting this up are different for each driver.

> Is it worth adding a standard API for this as an optional extension to the
> DB-API 2.0? Enough backends now support this that I suspect it is worth
> doing this now to avoid unnecessary incompatibilities between backend
> specific database APIs.

I'm not sure I can follow you here: if you do two-phase commit
under the control of a transaction manager such as MQSeries
or MS DTS, then the transaction manager will take care of
the transaction, not the database interface (see e.g. the DCOracle2
XA example in http://pymqi.sourceforge.net/).

-- 
Marc-Andre Lemburg
eGenix.com

Professional Python Services directly from the Source  (#1, Jun 22 2006)
>>> Python/Zope Consulting and Support ...        http://www.egenix.com/
>>> mxODBC.Zope.Database.Adapter ...             http://zope.egenix.com/
>>> mxODBC, mxDateTime, mxTextTools ...        http://python.egenix.com/
________________________________________________________________________
2006-07-03: EuroPython 2006, CERN, Switzerland              10 days left

::: Try mxODBC.Zope.DA for Windows,Linux,Solaris,FreeBSD for free ! ::::

From davidrushby at yahoo.com  Thu Jun 22 14:28:08 2006
From: davidrushby at yahoo.com (David Rushby)
Date: Thu, 22 Jun 2006 05:28:08 -0700 (PDT)
Subject: [DB-SIG] Two phase commit API
In-Reply-To: <449A319D.5030903@stuartbishop.net>
Message-ID: <20060622122808.86493.qmail@web30002.mail.mud.yahoo.com>

--- Stuart Bishop <stuart at stuartbishop.net> wrote:
> Are there any drivers out there that support two phase commit.

KInterbasDB does.

> If so, what syntax do they use?

The Connection class has a prepare method that triggers the first phase
of two-phase commit.  The normal commit method then performs the second
phase.

There's also a ConnectionGroup class that makes it more convenient to
deal with a group of Connections that are all participating in the same
distributed transaction.

Here's an example:
---
import kinterbasdb

# Establish multiple connections the usual way:
con1 = kinterbasdb.connect(dsn='weasel:/temp/test.db', user='sysdba',
password='pass')
con2 = kinterbasdb.connect(dsn='coyote:/temp/test.db', user='sysdba',
password='pass')

# Create a ConnectionGroup to associate multiple connections in such a
# way that they can participate in a distributed transaction.
group = kinterbasdb.ConnectionGroup(connections=(con1,con2))

# Start a distributed transaction involving all of the members of 
# the group (con1 and con2 in this case) with one of the following
# approaches:
#   - Call  group.begin()
#   - Call  con1.begin(); the operation will "bubble upward" and 
#     apply to the group.
#   - Call  con2.begin(); the operation will "bubble upward" and 
#     apply to the group.
#   - Just start executing some SQL statements on either con1 or con2.
#     A transaction will be started implicitly; it will be a 
#     distributed transaction because con1 and con2 are members 
#     of a ConnectionGroup.
group.begin()

# Perform some database changes the usual way (via cursors on con1 and
con2):
...

# Commit or roll back the distributed transaction by calling the 
# commit or rollback method of the ConnectionGroup itself, or the
# commit or rollback method of any member connection (con1 or 
# con2 in this case).
group.commit()

# Unless you want to perform another distributed transaction, 
# disband the group so that member connections can operate 
# independently again.
group.clear()
---

__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around 
http://mail.yahoo.com 

From stuart at stuartbishop.net  Tue Jun 27 09:03:11 2006
From: stuart at stuartbishop.net (Stuart Bishop)
Date: Tue, 27 Jun 2006 14:03:11 +0700
Subject: [DB-SIG] Two phase commit API
In-Reply-To: <449A48CB.1050501@egenix.com>
References: <449A319D.5030903@stuartbishop.net> <449A48CB.1050501@egenix.com>
Message-ID: <44A0D82F.1030202@stuartbishop.net>

M.-A. Lemburg wrote:
> Stuart Bishop wrote:
>> Hi.
>>
>> Are there any drivers out there that support two phase commit.
>>
>> If so, what syntax do they use?
> 
> I'm not aware of any native driver that does support this, except a
> patched DCOracle2:
> 
> http://pymqi.sourceforge.net/
> 
> You can also use mxODBC with an XA enabled ODBC driver (I think
> the EasySoft Oracle ODBC driver is capable of doing XA), but the
> APIs for setting this up are different for each driver.
> 
>> Is it worth adding a standard API for this as an optional extension to the
>> DB-API 2.0? Enough backends now support this that I suspect it is worth
>> doing this now to avoid unnecessary incompatibilities between backend
>> specific database APIs.
> 
> I'm not sure I can follow you here: if you do two-phase commit
> under the control of a transaction manager such as MQSeries
> or MS DTS, then the transaction manager will take care of
> the transaction, not the database interface (see e.g. the DCOracle2
> XA example in http://pymqi.sourceforge.net/).

My objective is to add the functionality to psycopg now that PostgreSQL
supports two phase commit. I'm not interested in using a third party
transaction manager - just something like the following (using KInterbaseDB
prepare() method - thanks David):

>>> con1 = connect('dbname=db1')
>>> con2 = connect('dbnane=db2')
[ Make changes to both databases ]
>>> # These prepares may raise exceptions if database limits are
>>> # reached or serialization exceptions raised from running in
>>> # serializable transaction isolation level.
>>> con1.prepare()
>>> con2.prepare()
>>> # These commits guaranteed to succeed except in extraordinary
>>> # circumstances.
>>> con1.commit()
>>> con2.commit()

This can also be used to correctly hook the database adapters into Zope or
other transactional systems that support two phase commit to avoid the rare
but possible data corruption that can occur when dealing with multiple
databases.

-- 
Stuart Bishop <stuart at stuartbishop.net>
http://www.stuartbishop.net/

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