cx-oracle-users — Primary discussion list for users (and developers) of cx_Oracle

Re: [cx-oracle-users] Can't get nextval

[Anthony T. <an...@co...>]

It isn't strictly necessary to select from dual when you are fetching a
sequence value -- but it is the "accepted" way of doing so since dual
always has one row. Have you tried selecting from dual and does that
solve the problem? It is certainly not necessary to create a stored
procedure to do this -- you can do this in two separate SQL statement if
you wish or as an anonymous PL/SQL block as well. A stored procedure
simply encapsulates the logic in one place and that might be
advantageous to you. If you want to proceed further, I would suggest
sending us the exact code that you are using and the exact output --
using the interactive command line is ideal if you can do it. Thanks.

On Fri, 2004-02-27 at 00:46, Jon and Chiarina Blake wrote:
> Hi Antonio,
>   If you want to treat your sequence like a "table", you must "SELECT
> users_seq.nextval FROM DUAL". You'll see the next sequence value if you
> execute this statement from an SQL*Plus prompt.
> 
> What you seem to be attempting to do, only makes sence from a PL/SQL block.
> Try something like:
> 
> CREATE OR REPLACE PROCEDURE myproc IS
> 
>   nval NUMBER;
> 
> BEGIN
>   SELECT users_seq.nextval INTO nval FROM DUAL;
>   INSERT INTO xxx VALUES(nval,...);
>   ...
> END;
> 
> Then use cx_Oracle's callproc method to execute procedure myproc.
> Hope this helps.
> 
> Regards,
>   Jon
> 
> ----- Original Message ----- 
> From: "Antonio Beamud Montero" <ant...@li...>
> To: <cx-...@li...>
> Sent: Thursday, February 26, 2004 10:56 PM
> Subject: [cx-oracle-users] Can't get nextval
> 
> 
> Hi all:
> I've a big problem because I neet to get the nextval in a sequence, and the
> query returns an empty sequence.
> If I make a query like : INSERT INTO XXXX VALUES (users_seq.nextval, ...)
> All works perfectly, but If I try to do this query in two steps:
> SELECT users_seq.nextval FROM XXXX
> INSERT INTO XXXX VALUES (new_id, ...)
> 
> the SELECT returns [].
> (This query works with sqlplus)
> 
> What I'm doin wrong?
> 
> 
> -------------------------------------------------------
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> 
> 
> 
> 
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-- 
Anthony Tuininga
an...@co...
 
Computronix
Distinctive Software. Real People.
Suite 200, 10216 - 124 Street NW
Edmonton, AB, Canada  T5N 4A3
Phone:	(780) 454-3700
Fax:	(780) 454-3838
http://www.computronix.com

Re: [cx-oracle-users] Can't get nextval

[Jon a. C. B. <jc....@bi...>]

Hi Antonio,
  If you want to treat your sequence like a "table", you must "SELECT
users_seq.nextval FROM DUAL". You'll see the next sequence value if you
execute this statement from an SQL*Plus prompt.

What you seem to be attempting to do, only makes sence from a PL/SQL block.
Try something like:

CREATE OR REPLACE PROCEDURE myproc IS

  nval NUMBER;

BEGIN
  SELECT users_seq.nextval INTO nval FROM DUAL;
  INSERT INTO xxx VALUES(nval,...);
  ...
END;

Then use cx_Oracle's callproc method to execute procedure myproc.
Hope this helps.

Regards,
  Jon

----- Original Message ----- 
From: "Antonio Beamud Montero" <ant...@li...>
To: <cx-...@li...>
Sent: Thursday, February 26, 2004 10:56 PM
Subject: [cx-oracle-users] Can't get nextval


Hi all:
I've a big problem because I neet to get the nextval in a sequence, and the
query returns an empty sequence.
If I make a query like : INSERT INTO XXXX VALUES (users_seq.nextval, ...)
All works perfectly, but If I try to do this query in two steps:
SELECT users_seq.nextval FROM XXXX
INSERT INTO XXXX VALUES (new_id, ...)

the SELECT returns [].
(This query works with sqlplus)

What I'm doin wrong?


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RE: [cx-oracle-users] Can't get nextval

[Moore, P. <Pau...@at...>]

From: Antonio Beamud Montero
> query =3D "SELECT allocation_seq.nextval FROM allocation"
> self._cursor.execute(query)
> newid, =3D self._cursor.fetchone()
> print newid

> But it returns nothing...=20

Select from dual instead of from allocation. I'm guessing that your
allocation table is empty.

Paul

Re: [cx-oracle-users] Can't get nextval

[Antonio B. M. <ant...@li...>]

query =3D "SELECT allocation_seq.nextval FROM allocation"
self._cursor.execute(query)
newid, =3D self._cursor.fetchone()
print newid

But it returns nothing...=20
If I do:
self._cursor.execute('select * from user_sequences')
r =3D self._cursor.fetchall()
print r
-------------------
[('ALLOCATION_SEQ', 1, 999999999999999999999999999L, 1, 'N', 'N', 20, 81)=
]
-------------------

El Jue 26 Feb 2004 15:54, Anthony Tuininga escribi=F3:
> Could you send us the exact code you are using? This code works for me:
>
> import cx_Oracle
>
> connection =3D cx_Oracle.connect("user/pw@tns")
> cursor =3D connection.cursor()
> cursor.execute("select users_seq.nextval from dual")
> seqValue, =3D cursor.fetchone()
>
> On Thu, 2004-02-26 at 04:56, Antonio Beamud Montero wrote:
> > Hi all:
> > I've a big problem because I neet to get the nextval in a sequence, a=
nd
> > the query returns an empty sequence.
> > If I make a query like : INSERT INTO XXXX VALUES (users_seq.nextval, =
=2E..)
> > All works perfectly, but If I try to do this query in two steps:
> > SELECT users_seq.nextval FROM XXXX
> > INSERT INTO XXXX VALUES (new_id, ...)
> >
> > the SELECT returns [].
> > (This query works with sqlplus)
> >
> > What I'm doin wrong?
> >
> >
> > -------------------------------------------------------
> > SF.Net is sponsored by: Speed Start Your Linux Apps Now.
> > Build and deploy apps & Web services for Linux with
> > a free DVD software kit from IBM. Click Now!
> > http://ads.osdn.com/?ad_id56&alloc_id438&op=3Dclick
> > _______________________________________________
> > cx-oracle-users mailing list
> > cx-...@li...
> > https://lists.sourceforge.net/lists/listinfo/cx-oracle-users

Re: [cx-oracle-users] Can't get nextval

[Anthony T. <an...@co...>]

Could you send us the exact code you are using? This code works for me:

import cx_Oracle

connection = cx_Oracle.connect("user/pw@tns")
cursor = connection.cursor()
cursor.execute("select users_seq.nextval from dual")
seqValue, = cursor.fetchone()

On Thu, 2004-02-26 at 04:56, Antonio Beamud Montero wrote:
> Hi all:
> I've a big problem because I neet to get the nextval in a sequence, and the 
> query returns an empty sequence. 
> If I make a query like : INSERT INTO XXXX VALUES (users_seq.nextval, ...)
> All works perfectly, but If I try to do this query in two steps:
> SELECT users_seq.nextval FROM XXXX
> INSERT INTO XXXX VALUES (new_id, ...)
> 
> the SELECT returns [].
> (This query works with sqlplus)
> 
> What I'm doin wrong?
> 
> 
> -------------------------------------------------------
> SF.Net is sponsored by: Speed Start Your Linux Apps Now.
> Build and deploy apps & Web services for Linux with
> a free DVD software kit from IBM. Click Now!
> http://ads.osdn.com/?ad_id56&alloc_id438&op=click
> _______________________________________________
> cx-oracle-users mailing list
> cx-...@li...
> https://lists.sourceforge.net/lists/listinfo/cx-oracle-users
-- 
Anthony Tuininga
an...@co...
 
Computronix
Distinctive Software. Real People.
Suite 200, 10216 - 124 Street NW
Edmonton, AB, Canada  T5N 4A3
Phone:	(780) 454-3700
Fax:	(780) 454-3838
http://www.computronix.com

[cx-oracle-users] Can't get nextval

[Antonio B. M. <ant...@li...>]

Hi all:
I've a big problem because I neet to get the nextval in a sequence, and t=
he=20
query returns an empty sequence.=20
If I make a query like : INSERT INTO XXXX VALUES (users_seq.nextval, ...)
All works perfectly, but If I try to do this query in two steps:
SELECT users_seq.nextval FROM XXXX
INSERT INTO XXXX VALUES (new_id, ...)

the SELECT returns [].
(This query works with sqlplus)

What I'm doin wrong?

Re: [cx-oracle-users] Extracting Oracle error codes, characterizing exceptions

[Anthony T. <an...@co...>]

The only other interesting piece of information might be the following:

Python exceptions have an "args" attribute which in this case is a
singleton tuple containing an error info object. This error info object
has three attributes:

code - the numeric Oracle code
message - the message that is obtained via str(exceptionValue)
context - the context in which the error was raised

As to your other question about the fact that cx_Oracle always raises
DatabseError when it would seem more reasonable to return something like
DataError -- I haven't gone to the trouble of creating a mapping between
Oracle errors and DB API errors. Someone (possibly on this list) said
they were going to send me patches for this but I haven't heard from
them in several months so perhaps not.... If you would like to pick up
that ball, I'm quite willing to accept patches. :-) Otherwise, I have
other things which I would like to do that I would consider higher
priority... :-)

On Tue, 2004-02-17 at 04:30, ????? ???? wrote:
> Hi,
> 
> 
> 
> Try like in this
> short example:
> 
> 
> ------------------------------------------------<cut>-----------------------
> --------------------
> try:
>     my_connection=cx_Oracle.connect('system/manager@test_db')
> except cx_Oracle.DatabaseError,info:
>     print "Logon  Error:",info
>     exit(0)
> 
> my_cursor=my_connection.cursor()
> try:
>     my_cursor.execute("""
>     SELECT ROWID,O.* FROM TESTER.PODR O  """)
> except cx_Oracle.DatabaseError,info:
>     print "SQL Error:",info
>     exit(0)
> ------------------------------<end cut
> >-------------------------------------
> 
> 
> Best regards,
> 
> Oleg Popov
> op...@ya...
> 
> 
> ----- Original Message -----
> From: "Jeff Wong" <jef...@sa...>
> To: <cx-...@li...>
> Sent: Monday, February 16, 2004 11:41 PM
> Subject: [cx-oracle-users] Extracting Oracle error codes, characterizing
> exceptions
> 
> 
> > Is there way to extract Oracle error codes other than by applying str() to
> > the exception and parsing the string?
> >
> > Also, if I cannot connect to the Oracle database would that be a
> > DatabaseError or an InternalError?
> >
> > I am trying to use cx_Oracle to write a server that needs to be reliable
> > and I am trying to figure out how to handle possible exceptions returned
> > from Oracle.
> >
> > I also noticed that violations of table constraints are DatabaseErrors,
> > rather than DataErrors.  Is this intended?  What are examples of
> > DataErrors?
> >
> > Thanks,
> >
> > Jeff
> >
> >
> >
> >
> >
> >
> > -------------------------------------------------------
> > SF.Net is sponsored by: Speed Start Your Linux Apps Now.
> > Build and deploy apps & Web services for Linux with
> > a free DVD software kit from IBM. Click Now!
> > http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click
> > _______________________________________________
> > cx-oracle-users mailing list
> > cx-...@li...
> > https://lists.sourceforge.net/lists/listinfo/cx-oracle-users
> >
> 
> 
> 
> -------------------------------------------------------
> SF.Net is sponsored by: Speed Start Your Linux Apps Now.
> Build and deploy apps & Web services for Linux with
> a free DVD software kit from IBM. Click Now!
> http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click
> _______________________________________________
> cx-oracle-users mailing list
> cx-...@li...
> https://lists.sourceforge.net/lists/listinfo/cx-oracle-users
-- 
Anthony Tuininga
an...@co...
 
Computronix
Distinctive Software. Real People.
Suite 200, 10216 - 124 Street NW
Edmonton, AB, Canada  T5N 4A3
Phone:	(780) 454-3700
Fax:	(780) 454-3838
http://www.computronix.com

Re: [cx-oracle-users] Extracting Oracle error codes, characterizing exceptions

[????? ???? <op...@sa...>]

Hi,



Try like in this
short example:


------------------------------------------------<cut>-----------------------
--------------------
try:
    my_connection=cx_Oracle.connect('system/manager@test_db')
except cx_Oracle.DatabaseError,info:
    print "Logon  Error:",info
    exit(0)

my_cursor=my_connection.cursor()
try:
    my_cursor.execute("""
    SELECT ROWID,O.* FROM TESTER.PODR O  """)
except cx_Oracle.DatabaseError,info:
    print "SQL Error:",info
    exit(0)
------------------------------<end cut
>-------------------------------------


Best regards,

Oleg Popov
op...@ya...


----- Original Message -----
From: "Jeff Wong" <jef...@sa...>
To: <cx-...@li...>
Sent: Monday, February 16, 2004 11:41 PM
Subject: [cx-oracle-users] Extracting Oracle error codes, characterizing
exceptions


> Is there way to extract Oracle error codes other than by applying str() to
> the exception and parsing the string?
>
> Also, if I cannot connect to the Oracle database would that be a
> DatabaseError or an InternalError?
>
> I am trying to use cx_Oracle to write a server that needs to be reliable
> and I am trying to figure out how to handle possible exceptions returned
> from Oracle.
>
> I also noticed that violations of table constraints are DatabaseErrors,
> rather than DataErrors.  Is this intended?  What are examples of
> DataErrors?
>
> Thanks,
>
> Jeff
>
>
>
>
>
>
> -------------------------------------------------------
> SF.Net is sponsored by: Speed Start Your Linux Apps Now.
> Build and deploy apps & Web services for Linux with
> a free DVD software kit from IBM. Click Now!
> http://ads.osdn.com/?ad_id=1356&alloc_id=3438&op=click
> _______________________________________________
> cx-oracle-users mailing list
> cx-...@li...
> https://lists.sourceforge.net/lists/listinfo/cx-oracle-users
>

[cx-oracle-users] Extracting Oracle error codes, characterizing exceptions

[Jeff W. <jef...@sa...>]

Is there way to extract Oracle error codes other than by applying str() to
the exception and parsing the string?

Also, if I cannot connect to the Oracle database would that be a
DatabaseError or an InternalError?  

I am trying to use cx_Oracle to write a server that needs to be reliable
and I am trying to figure out how to handle possible exceptions returned
from Oracle.

I also noticed that violations of table constraints are DatabaseErrors,
rather than DataErrors.  Is this intended?  What are examples of
DataErrors?

Thanks,

Jeff

[cx-oracle-users] Terminating an execute_many()

[Jeff W. <jef...@sa...>]

Hi,

Let's say I'm running an execute_many() on an SQL statement and at some
point I decide it's taking to long.  What is the best or cleanest way to
terminate this execution?


Here's some further background info:  I have 2 threads: one which does
database insertions, and another which monitors that thread.  From the
monitoring thread, I want to arbitrarily raise an exception such that the
inserting thread stops what it's doing.  The insertion thread does the
"insertions" is the MainThread.

I've tried:  

1)	Sending a SIGTERM to the MainThread, catching it in a handler
	that I have installed, and doing sys.exit() from the handler.  

2) 	Calling sys.exit() from the monitoring thread when the insertion
	thread is busy doing the execute many.

3)	Sending a SIGINT to the MainThread.

None of these terminate the transaction execute_many() right away.  

Is there any way to do this on cx_Oracle 3.0?  I noticed that Connection
objects in 4.0 have cancel() function.  Is this what I want?

TIA,

Jeff

	

Re: [cx-oracle-users] Is it possible to get an error number from a cx_Oracle.Exception object?

[Anthony T. <an...@co...>]

It is possible but the method isn't much of an improvement over the code
below. :-( If anyone has an idea of how to create an exception in C that
makes this a little more reasonable, please let me know!

except cx_Oracle.DatabaseError, e:
    errorObj, = e.args
    if errorObj.code == 904:
        # handle this error

There are three attributes on the errorObj object:

code --> the numeric error code reported by Oracle
message --> the message reported by Oracle
context --> internal context in which the error was raised

Hope that helps.

On Wed, 2004-01-21 at 09:05, Moore, Paul wrote:
> I want to trap a particular Oracle error (904, invalid column name).
> At the moment, I'm doing that by
> 
>     except cx_Oracle.DatabaseError, e:
>         if str(e).startswith("ORA-00904"):
>             # handle this error
> 
> While I can't imagine that the string format of the error will ever
> change enough to make this invalid, I'd prefer to check the error number
> directly. But I can't see a way of getting that number.
> 
> Am I missing it, or is this not possible?
> 
> Thanks,
> Paul.
> 
> 
> -------------------------------------------------------
> The SF.Net email is sponsored by EclipseCon 2004
> Premiere Conference on Open Tools Development and Integration
> See the breadth of Eclipse activity. February 3-5 in Anaheim, CA.
> http://www.eclipsecon.org/osdn
> _______________________________________________
> cx-oracle-users mailing list
> cx-...@li...
> https://lists.sourceforge.net/lists/listinfo/cx-oracle-users
-- 

[cx-oracle-users] Is it possible to get an error number from a cx_Oracle.Exception object?

[Moore, P. <Pau...@at...>]

I want to trap a particular Oracle error (904, invalid column name).
At the moment, I'm doing that by

    except cx_Oracle.DatabaseError, e:
        if str(e).startswith("ORA-00904"):
            # handle this error

While I can't imagine that the string format of the error will ever
change enough to make this invalid, I'd prefer to check the error number
directly. But I can't see a way of getting that number.

Am I missing it, or is this not possible?

Thanks,
Paul.

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[cx-oracle-users] This group is now available via gmane

[Moore, P. <Pau...@at...>]

It should be available from the gmane archive
(see http://www.gmane.org).

Having said that, the group isn't there yet, but
that may just be because no messages have been posted
since the group creation. Hopefully, this message will
fix that :-)

Paul.

Re: Re: [cx-oracle-users] Installation problem on mandrake 9.2

[Anthony T. <an...@co...>]

You need to have your Oracle client installed. If you have it installed,
make sure the environment variable ORACLE_HOME points to the correct
location.

On Fri, 2004-01-16 at 11:48, chr...@ne... wrote:
> Anthony,
> 
> Thanks. When I run the setup.py build, I get the following error message:
> 
> Traceback (most recent call last):
>     File "setup.py", line 34, in ?
>         oracleHome = os.environ["ORACLE_HOME"]
>     File "/usr/lib/python2.3/UserDict.py", line 19, in __getitem__
>         def __getitem__(self, key): return self.data[key]
> KeyError: 'ORACLE_HOME'
> 
> Thanks again,
> Chris
> 
> ----- Original Message -----
> From: Anthony Tuininga
> Sent: 1/16/2004 7:21:00 AM
> To: ch...@ja...
> Cc: cx-...@li...
> Subject: Re: [cx-oracle-users] Installation problem on mandrake 9.2
> 
> > Try executing the following:
> > 
> > rpm -qa | grep cx_Oracle
> > 
> > and see if anything turns up. If so, execute the following:
> > 
> > rpm -ql cx_Oracle
> > 
> > and note where the files are located. It is possible that your Python
> > installation and the cx_Oracle RPM are not compatible -- your Python
> > executes in /usr/local/bin but the cx_Oracle RPM expects a Python from
> > /usr/bin.
> > 
> > If the RPM doesn't work for you, you should be able to download the
> > source and execute (from within the directory where the source was
> > extracted):
> > 
> > python setup.py build
> > python setup.py install
> > 
> > and that should install it for you.
> > 
> > Hope that helps.
> > 
> > On Thu, 2004-01-15 at 18:00, Christopher Abrams wrote:
> > > Hello cx-oracle-users,
> > > 
> > > I'm having trouble installing cx_Oracle 4.0 on a Mandrake 9.2 box. I
> > > am fairly new to Mandrake and Linux in general. I've tried to search
> > > for a package for cx_Oracle using drakconf (urpmi), but I haven't had
> > > any luck. I've also searched around the web for some help. I
> > > downloaded the rpm from the cx_Oracle page, but when I rpm -i the
> > > package doesn't seem to get installed. I also don't get any error
> > > messages. If anyone knows of anything that would help, it would be
> > > greatly appreciated.
> > > 
> > > Thanks,
> > > Chris
> > > 
> > > 
> > > -------------------------------------------------------
> > > The SF.Net email is sponsored by EclipseCon 2004
> > > Premiere Conference on Open Tools Development and Integration
> > > See the breadth of Eclipse activity. February 3-5 in Anaheim, CA.
> > > http://www.eclipsecon.org/osdn
> > > _______________________________________________
> > > cx-oracle-users mailing list
> > > cx-...@li...
> > > https://lists.sourceforge.net/lists/listinfo/cx-oracle-users
> > -- 
> > Anthony Tuininga
> > an...@co...
> >  
> > Computronix
> > Distinctive Software. Real People.
> > Suite 200, 10216 - 124 Street NW
> > Edmonton, AB, Canada  T5N 4A3
> > Phone:	(780) 454-3700
> > Fax:	(780) 454-3838
> > http://www.computronix.com
> > 
> > 
> > 
> > -------------------------------------------------------
> > The SF.Net email is sponsored by EclipseCon 2004
> > Premiere Conference on Open Tools Development and Integration
> > See the breadth of Eclipse activity. February 3-5 in Anaheim, CA.
> > http://www.eclipsecon.org/osdn
> > _______________________________________________
> > cx-oracle-users mailing list
> > cx-...@li...
> > https://lists.sourceforge.net/lists/listinfo/cx-oracle-users
-- 
Anthony Tuininga
an...@co...
 
Computronix
Distinctive Software. Real People.
Suite 200, 10216 - 124 Street NW
Edmonton, AB, Canada  T5N 4A3
Phone:	(780) 454-3700
Fax:	(780) 454-3838
http://www.computronix.com

Re: Re: [cx-oracle-users] Installation problem on mandrake 9.2

[<chr...@ne...>]

Anthony,

Thanks=2E When I run the setup=2Epy build, I get the following error message:=


Traceback (most recent call last):
    File "setup=2Epy", line 34, in ?
        oracleHome =3D os=2Eenviron["ORACLE_HOME"]
    File "/usr/lib/python2=2E3/UserDict=2Epy", line 19, in __getitem__
        def __getitem__(self, key): return self=2Edata[key]
KeyError: 'ORACLE_HOME'

Thanks again,
Chris

----- Original Message -----
From: Anthony Tuininga
Sent: 1/16/2004 7:21:00 AM
To: chrisa@jakks=2Enet
Cc: cx-oracle-users@lists=2Esourceforge=2Enet
Subject: Re: [cx-oracle-users] Installation problem on mandrake 9=2E2

> Try executing the following:
>=20
> rpm -qa | grep cx_Oracle
>=20
> and see if anything turns up=2E If so, execute the following:
>=20
> rpm -ql cx_Oracle
>=20
> and note where the files are located=2E It is possible that your Python
> installation and the cx_Oracle RPM are not compatible -- your Python
> executes in /usr/local/bin but the cx_Oracle RPM expects a Python from
> /usr/bin=2E
>=20
> If the RPM doesn't work for you, you should be able to download the
> source and execute (from within the directory where the source was
> extracted):
>=20
> python setup=2Epy build
> python setup=2Epy install
>=20
> and that should install it for you=2E
>=20
> Hope that helps=2E
>=20
> On Thu, 2004-01-15 at 18:00, Christopher Abrams wrote:
> > Hello cx-oracle-users,
> >=20
> > I'm having trouble installing cx_Oracle 4=2E0 on a Mandrake 9=2E2 box=2E=
 I
> > am fairly new to Mandrake and Linux in general=2E I've tried to search
> > for a package for cx_Oracle using drakconf (urpmi), but I haven't had
> > any luck=2E I've also searched around the web for some help=2E I
> > downloaded the rpm from the cx_Oracle page, but when I rpm -i the
> > package doesn't seem to get installed=2E I also don't get any error
> > messages=2E If anyone knows of anything that would help, it would be
> > greatly appreciated=2E
> >=20
> > Thanks,
> > Chris
> >=20
> >=20
> > -------------------------------------------------------
> > The SF=2ENet email is sponsored by EclipseCon 2004
> > Premiere Conference on Open Tools Development and Integration
> > See the breadth of Eclipse activity=2E February 3-5 in Anaheim, CA=2E
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> > cx-oracle-users mailing list
> > cx-oracle-users@lists=2Esourceforge=2Enet
> > https://lists=2Esourceforge=2Enet/lists/listinfo/cx-oracle-users
> --=20
> Anthony Tuininga
> anthony@computronix=2Ecom
> =20
> Computronix
> Distinctive Software=2E Real People=2E
> Suite 200, 10216 - 124 Street NW
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>=20
>=20
>=20
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> cx-oracle-users@lists=2Esourceforge=2Enet
> https://lists=2Esourceforge=2Enet/lists/listinfo/cx-oracle-users

Re: [cx-oracle-users] Installation problem on mandrake 9.2

[Anthony T. <an...@co...>]

Try executing the following:

rpm -qa | grep cx_Oracle

and see if anything turns up. If so, execute the following:

rpm -ql cx_Oracle

and note where the files are located. It is possible that your Python
installation and the cx_Oracle RPM are not compatible -- your Python
executes in /usr/local/bin but the cx_Oracle RPM expects a Python from
/usr/bin.

If the RPM doesn't work for you, you should be able to download the
source and execute (from within the directory where the source was
extracted):

python setup.py build
python setup.py install

and that should install it for you.

Hope that helps.

On Thu, 2004-01-15 at 18:00, Christopher Abrams wrote:
> Hello cx-oracle-users,
> 
> I'm having trouble installing cx_Oracle 4.0 on a Mandrake 9.2 box. I
> am fairly new to Mandrake and Linux in general. I've tried to search
> for a package for cx_Oracle using drakconf (urpmi), but I haven't had
> any luck. I've also searched around the web for some help. I
> downloaded the rpm from the cx_Oracle page, but when I rpm -i the
> package doesn't seem to get installed. I also don't get any error
> messages. If anyone knows of anything that would help, it would be
> greatly appreciated.
> 
> Thanks,
> Chris
> 
> 
> -------------------------------------------------------
> The SF.Net email is sponsored by EclipseCon 2004
> Premiere Conference on Open Tools Development and Integration
> See the breadth of Eclipse activity. February 3-5 in Anaheim, CA.
> http://www.eclipsecon.org/osdn
> _______________________________________________
> cx-oracle-users mailing list
> cx-...@li...
> https://lists.sourceforge.net/lists/listinfo/cx-oracle-users
-- 
Anthony Tuininga
an...@co...
 
Computronix
Distinctive Software. Real People.
Suite 200, 10216 - 124 Street NW
Edmonton, AB, Canada  T5N 4A3
Phone:	(780) 454-3700
Fax:	(780) 454-3838
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[cx-oracle-users] Installation problem on mandrake 9.2

[Christopher A. <ch...@ja...>]

Hello cx-oracle-users,

I'm having trouble installing cx_Oracle 4.0 on a Mandrake 9.2 box. I am =
fairly new to Mandrake and Linux in general. I've tried to search for a =
package for cx_Oracle using drakconf (urpmi), but I haven't had any =
luck. I've also searched around the web for some help. I downloaded the =
rpm from the cx_Oracle page, but when I rpm -i the package doesn't seem =
to get installed. I also don't get any error messages. If anyone knows =
of anything that would help, it would be greatly appreciated.

Thanks,
Chris

RE: [cx-oracle-users] Creating a large number of database connections

[Anthony T. <an...@co...>]

On Thu, 2004-01-15 at 09:32, Moore, Paul wrote:
> From: Anthony Tuininga [mailto:an...@co...]
> > Could you explain about the "cursors only used from a single
> > thread" problem is?
> 
> Sorry. Basically, I'm running a query against lots of databases,
> and storing the results in a central database. So I have a single
> connection to the central DB, against which I'm running a series
> of inserts.

Ok, that makes sense now. :-)

> Hmm, maybe I should be sharing the central *connection* between
> the multiple threads, and creating individual cursors to do the
> inserts on a per-thread basis. Is that OK? (Am I reading the
> documentation right that I can share a connection, but not a
> cursor?)

Yes, you can share the connection, but don't try sharing a cursor,
unless you like segfaults, of course. :-)
> 
> > I am assuming here that you have one connection per
> > thread and therefore one cursor per thread so there shouldn't
> > be a problem here, right?
> 
> It's passing the data back to a central update thread that hurts.
> Mucking about with queues, knowing when the threads have completed,
> etc :-(

Although you __can__ create a separate cursor for each thread and
perform the insert in each separate thread, if you have a large number
of them, this can hurt you. At that point, the queue will work in your
favor because the prepare() phase can be skipped. The difference is
probably a few milliseconds per thread so it is significantly smaller
than the connection overhead (at least 35 ms). Your call. :-)

> > This code:
> [...]
> > will definitely be slower than this code:
> 
> > def PerformQuery(db):
> >     connection = cx_Oracle.connect("user", "pw", db)
> >     cursor = connection.cursor()
> >     cursor.execute("some_query")
> 
> > for db in listOfDbs:
> >     thread = thread.start_new_thread(PerformQuery, (db,))
> 
> > Of course, you need to add synchronization code which is completely
> > missing but I can help you with that, if needed. I've written a few
> > threaded programs and I know the pitfalls that can suddenly open up
> > beneath your feet. :-)
> 
> Thanks for the offer. I've managed to find a lot of thread pitfalls
> myself :-)

They're amazingly easy to find, eh? That's why I've written a few simple
classes to manage such things as queues and the like so that I don't
have to think about it each time. :-)

> How likely is the following sketch to work? (I'll try it, but one of
> the things I have learned is that running a threaded program twice
> exposes two different sets of bugs :-))
> 
> cx_Oracle.OPT_Threading = 1 # I think I need this?

Yes, you definitely need this. Without it, your program will crash and
burn rather quickly. It turns on Oracle threading mode. I've considered
making this a part of the connect() method but it really does need to be
global. Perhaps another method might make it more clear. Something like
this, perhaps?

cx_Oracle.setthreaded()

Any thoughts on that?

> def PerformQuery(db, cn):
>     connection = cx_Oracle.connect("user", "pw", db)
>     cursor = connection.cursor()
>     cursor.execute("some_query")
>     ins = cn.cursor()
>     insert_data = process(cursor.fetchall())
>     ins.executemany("insert_sql", insert_data)
> 
> cn = cx_Oracle.connect("user", "pw", "centraldb")
> threadlist = []
> for db in listOfDbs:
>     thread = thread.start_new_thread(PerformQuery, (db, cn))
>     threadlist.append(thread)
> 
> for thread in threadlist:
>     thread.join()
> 
> cn.commit()
> cn.close()

Yes, this should work. Of course, you might want to decide whether you
want to use the threading module or the thread module and then make the
necessary changes. :-)

> Paul
-- 
Anthony Tuininga
an...@co...
 
Computronix
Distinctive Software. Real People.
Suite 200, 10216 - 124 Street NW
Edmonton, AB, Canada  T5N 4A3
Phone:	(780) 454-3700
Fax:	(780) 454-3838
http://www.computronix.com

RE: [cx-oracle-users] Creating a large number of database connections

[Moore, P. <Pau...@at...>]

From: Anthony Tuininga [mailto:an...@co...]
> Could you explain about the "cursors only used from a single
> thread" problem is?

Sorry. Basically, I'm running a query against lots of databases,
and storing the results in a central database. So I have a single
connection to the central DB, against which I'm running a series
of inserts.

Hmm, maybe I should be sharing the central *connection* between
the multiple threads, and creating individual cursors to do the
inserts on a per-thread basis. Is that OK? (Am I reading the
documentation right that I can share a connection, but not a
cursor?)

> I am assuming here that you have one connection per
> thread and therefore one cursor per thread so there shouldn't
> be a problem here, right?

It's passing the data back to a central update thread that hurts.
Mucking about with queues, knowing when the threads have completed,
etc :-(

> This code:
[...]
> will definitely be slower than this code:

> def PerformQuery(db):
>     connection =3D cx_Oracle.connect("user", "pw", db)
>     cursor =3D connection.cursor()
>     cursor.execute("some_query")

> for db in listOfDbs:
>     thread =3D thread.start_new_thread(PerformQuery, (db,))

> Of course, you need to add synchronization code which is completely
> missing but I can help you with that, if needed. I've written a few
> threaded programs and I know the pitfalls that can suddenly open up
> beneath your feet. :-)

Thanks for the offer. I've managed to find a lot of thread pitfalls
myself :-)

How likely is the following sketch to work? (I'll try it, but one of
the things I have learned is that running a threaded program twice
exposes two different sets of bugs :-))

cx_Oracle.OPT_Threading =3D 1 # I think I need this?

def PerformQuery(db, cn):
    connection =3D cx_Oracle.connect("user", "pw", db)
    cursor =3D connection.cursor()
    cursor.execute("some_query")
    ins =3D cn.cursor()
    insert_data =3D process(cursor.fetchall())
    ins.executemany("insert_sql", insert_data)

cn =3D cx_Oracle.connect("user", "pw", "centraldb")
threadlist =3D []
for db in listOfDbs:
    thread =3D thread.start_new_thread(PerformQuery, (db, cn))
    threadlist.append(thread)

for thread in threadlist:
    thread.join()

cn.commit()
cn.close()

Paul

Re: [cx-oracle-users] Creating a large number of database connections

[Anthony T. <an...@co...>]

Oracle's threading overhead is about 10-15% so this likely will not be a
huge issue. Could you explain about the "cursors only used from a single
thread" problem is? I am assuming here that you have one connection per
thread and therefore one cursor per thread so there shouldn't be a
problem here, right?

This code:

for db in listOfDbs:
    connection = cx_Oracle.connect("user", "pw", db)
    cursor = connection.cursor()
    cursor.execute("some_query")

will definitely be slower than this code:

def PerformQuery(db):
    connection = cx_Oracle.connect("user", "pw", db)
    cursor = connection.cursor()
    cursor.execute("some_query")

for db in listOfDbs:
    thread = thread.start_new_thread(PerformQuery, (db,))

Of course, you need to add synchronization code which is completely
missing but I can help you with that, if needed. I've written a few
threaded programs and I know the pitfalls that can suddenly open up
beneath your feet. :-)

On Thu, 2004-01-15 at 04:54, Moore, Paul wrote:
> I have a program which needs to connect to a large number of
> databases. Each connection is fairly short-lived (run a single SQL
> query), but the connect times can be quite long, particularly as some
> databases may be inaccessible due to network issues, and so there's a
> long wait for timeouts.
> 
> What I'd like to do is to create all of my connections "in parallel",
> and then run the queries as the connections are ready. This would
> reduce the runtime of my application from the sum of all the connect
> times (plus a fixed overhead) to the maximum connect time (plus a
> possibly different fixed overhead).
> 
> At the moment, I'm doing this using multiple threads, but the extra
> code needed to handle the threads, and to make sure that cursors are
> only used from a single thread, is non-trivial. And there's also
> Oracle's threading overhead.
> 
> Is there a simpler way of doing this, that I am missing? I need a
> solution which will handle 100 or so connections, and will scale
> reasonably sensibly. My initial thought was that some form of
> non-blocking connect might work (I'm not an OCI expert), but when I
> scanned the OCI manuals, it doesn't seem like OCI lets you do any
> other database work while a nonblocking connect is in progress.
> 
> Can anyone suggest anything?
> 
> Thanks,
> Paul Moore.
> 
> 
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-- 
Anthony Tuininga
an...@co...
 
Computronix
Distinctive Software. Real People.
Suite 200, 10216 - 124 Street NW
Edmonton, AB, Canada  T5N 4A3
Phone:	(780) 454-3700
Fax:	(780) 454-3838
http://www.computronix.com

[cx-oracle-users] Creating a large number of database connections

[Moore, P. <Pau...@at...>]

I have a program which needs to connect to a large number of
databases. Each connection is fairly short-lived (run a single SQL
query), but the connect times can be quite long, particularly as some
databases may be inaccessible due to network issues, and so there's a
long wait for timeouts.

What I'd like to do is to create all of my connections "in parallel",
and then run the queries as the connections are ready. This would
reduce the runtime of my application from the sum of all the connect
times (plus a fixed overhead) to the maximum connect time (plus a
possibly different fixed overhead).

At the moment, I'm doing this using multiple threads, but the extra
code needed to handle the threads, and to make sure that cursors are
only used from a single thread, is non-trivial. And there's also
Oracle's threading overhead.

Is there a simpler way of doing this, that I am missing? I need a
solution which will handle 100 or so connections, and will scale
reasonably sensibly. My initial thought was that some form of
non-blocking connect might work (I'm not an OCI expert), but when I
scanned the OCI manuals, it doesn't seem like OCI lets you do any
other database work while a nonblocking connect is in progress.

Can anyone suggest anything?

Thanks,
Paul Moore.

[cx-oracle-users] Time() and TimeFromTicks() constructors

[Anthony T. <an...@co...>]

It has recently come to my attention that the presence of Time() and
TimeFromTicks() in cx_Oracle is misleading at best since Oracle does not
support the concept of a time only column.

The DB API document does not indicate that these constructors are
optional so I was wondering what the consensus of this list would be on
what ought to be done.

1) Remove the constructors.

2) Raise an exception when these constructors are used, indicating that
Oracle doesn't support the concept.

I lean towards number 2 myself but would like some feedback from others
on the list. In both cases the documentation will be updated to indicate
why these constructors do not work (or are not present).

It would also be useful if the DB API document would be modified
appropriately since (apparently) not all databases support the concept
of time only columns. There might be others that I am not aware of.

-- 
Anthony Tuininga
an...@co...
 
Computronix
Distinctive Software. Real People.
Suite 200, 10216 - 124 Street NW
Edmonton, AB, Canada  T5N 4A3
Phone:	(780) 454-3700
Fax:	(780) 454-3838
http://www.computronix.com

[cx-oracle-users] Oops!

[Anthony T. <an...@co...>]

I forgot to test all of the permutations and combinations on the less
commonly used platforms (Alpha, HP-UX and Solaris and perhaps others)
and I uncovered a couple of small bugs. :-( These have already been
fixed (today) but since they affect a very small portion of the code I
am going to hold off on releasing for at least a couple of weeks. If you
are directly affected by this, I can send you modified sources or
binaries.

If you are running Windows or Linux (x86) you are not affected by these
bugs.

1) cursor.bindnames() will cause cx_Oracle to crash

2) Session pooling will not function because of a missing trailing NULL
in the keyword parameters.

If you have any questions, fire away. And my apologies in advance to
those people who will be affected by these oopses.

If you discover anything else, please let me know as soon as possible so
that I can include any changes in a 4.0.1 release early next year.

-- 
Anthony Tuininga
an...@co...
 
Computronix
Distinctive Software. Real People.
Suite 200, 10216 - 124 Street NW
Edmonton, AB, Canada  T5N 4A3
Phone:	(780) 454-3700
Fax:	(780) 454-3838
http://www.computronix.com

RE: [cx-oracle-users] Segmentation Fault

[Antonio B. M. <ant...@li...>]

Well... I have get a reduced versión of the client runtime, but now it
has a size of 38 Mb... I have added the ocommon/nls/admin/data/* to my
rpm package and all works fine...

Thanks for all...

El jue, 18-12-2003 a las 16:53, Branimir Petrovic escribió:
> >Need I other libraries?
> >When I installed the full oracle client all works correctly...
> 
> At place I work at we had the similar idea - to include only few 
> needed items from Oracle Client install, in order to avoid the 
> rest of the bloat and we also faced similar problems. We then asked 
> Oracle for help in hunting/pinpointing what's needed and what can 
> safely be ignored and got somewhat surprising answer that although 
> that would be technically possible we are NOT allowed to do so. 
> Apparently some "fine print" explicitly forbids taking just few 
> selected pieces from Oracle Client, instead you must install ALL 
> that comes with it or else license to use the client is violated.
> To stay on the "safe side" we have to keep installing full 300+MB 
> of Oracle Client (9i) in order to be able to run our app that is
> 1/6 in size. Does not make sense, but - that's how it has to be...
> 
> Branimir
> 
> 
> 
> 
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Antonio Beamud Montero <ant...@li...>