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PyGreSQL and transactions 4+ messages / 3 participants [nested] [flat]
* PyGreSQL and transactions @ 2000-07-20 10:14 Nagy Laszlo Zsolt , KLTE TTK pm1 <nagylzs@dragon.klte.hu> 0 siblings, 1 reply; 4+ messages in thread From: Nagy Laszlo Zsolt , KLTE TTK pm1 @ 2000-07-20 10:14 UTC (permalink / raw) To: pgsql-interfaces Hi all. I'm writting a text-based server program with PyGreSQL. My first problem follows: >>> import pg >>> db = pg.DB('gandalf','localhost',5432,None,None,'gandalf','') >>> db.query('BEGIN') >>> db.query("INSERT INTO tbl(s) VALUES('value1')") NOTICE: current transaction is aborted, queries ignored until end of transaction block >>> db.query('commit') >>> The notice was sent to stderr, it seems that I have no way to catch it. There is getnotify(), but there is no getnotice(). I must catch it, because my server must know if the operation was successful. (It is in a multi-tier application's middle, and sends back a message about the operation.) Second problem: >>> lo = db.locreate(pg.INV_WRITE) >>> lo Closed large object, oid 18863 >>> lo.open(pg.INV_WRITE) Traceback (innermost last): File "<stdin>", line 1, in ? IOError: can't open large object. >>> I have compiled the PyGreSQL module without -DNO_LARGE. Thank in advance: Laszlo Nagy nagylzs@delfin.klte.hu ^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: PyGreSQL and transactions @ 2000-07-20 22:07 Billy G. Allie <Bill.Allie@mug.org> parent: Nagy Laszlo Zsolt , KLTE TTK pm1 <nagylzs@dragon.klte.hu> 0 siblings, 1 reply; 4+ messages in thread From: Billy G. Allie @ 2000-07-20 22:07 UTC (permalink / raw) To: Nagy Laszlo Zsolt , KLTE TTK pm1 <nagylzs@dragon.klte.hu>; +Cc: pgsql-interfaces "Nagy Laszlo Zsolt , KLTE TTK pm1" wrote: > > Hi all. > > I'm writting a text-based server program with PyGreSQL. > My first problem follows: > > >>> import pg > >>> db = pg.DB('gandalf','localhost',5432,None,None,'gandalf','') > >>> db.query('BEGIN') > >>> db.query("INSERT INTO tbl(s) VALUES('value1')") > NOTICE: current transaction is aborted, queries ignored until end of transaction block > >>> db.query('commit') > >>> > > The notice was sent to stderr, it seems that I have no way to catch it. > There is getnotify(), but there is no getnotice(). I must catch it, > because my server must know if the operation was successful. (It is > in a multi-tier application's middle, and sends back a message about > the operation.) > I have a Python to PostgreSQL interface program that I am preparing to release. It has the following features: 1. Support for cursors using 'DECLARE ... ' systax. 2. Support the following PostgreSQL typs as Python objects: PG_BOOL, PG_INT2, PG_INT4, PG_INT8, PG_FLOAT4 PG_FLOAT8, PG_CHAR, PG_VARCHAR, PG_TEXT, PG_BLOB (Large Objects), PG_NUMERIC The PG_NUMERIC support include *, /, +, and - operators. The PG_BLOB fully emulates a Python File Object except for truncate(). 3. Support for PostgreSQL arrays. They are converted to/from Python lists on input/output. 4. PostgreSQL notices are made available via the notices attribute of a connection object. The notices attribute is implemented as a list of notices such that connection.notices.pop() will return the first notice recieved from the back-end. Coalling pop() will return the next notice received, and so on. 5. Traps attempts to drop tables/indices, and unlinking large objects within a transasction. These actions are dangerous, since they can not be successfully rolled back with the current version of PostgreSQL. If the transactions were aborted or rolled back, the database will be left in a state where accessing the table, index, or large object that was dropped will result in an error because PostgreSQL can not access the file associated with the table/index/LO. I have been using the interface for about a week now without problems., but have only been using it on UnixWare 7.0. If you are interested in using the interface, I can send it to you and provide some assistance in porting it to your environement (if needed). > Second problem: > > >>> lo = db.locreate(pg.INV_WRITE) > >>> lo > Closed large object, oid 18863 > >>> lo.open(pg.INV_WRITE) > Traceback (innermost last): > File "<stdin>", line 1, in ? > IOError: can't open large object. > >>> Large Objects can only be opened and used in a transaction. -- ____ | Billy G. Allie | Domain....: Bill.Allie@mug.org | /| | 7436 Hartwell | Compuserve: 76337,2061 |-/-|----- | Dearborn, MI 48126| MSN.......: B_G_Allie@email.msn.com |/ |LLIE | (313) 582-1540 | ^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: PyGreSQL and transactions @ 2000-07-21 17:28 Jason Earl <jdearl@yahoo.com> 0 siblings, 0 replies; 4+ messages in thread From: Jason Earl @ 2000-07-21 17:28 UTC (permalink / raw) To: pgsql-interfaces "Nagy Laszlo Zsolt , KLTE TTK pm1" <nagylzs@dragon.klte.hu> writes: > Hi all. > > I'm writting a text-based server program with PyGreSQL. > My first problem follows: > > >>> import pg > >>> db = pg.DB('gandalf','localhost',5432,None,None,'gandalf','') > >>> db.query('BEGIN') > >>> db.query("INSERT INTO tbl(s) VALUES('value1')") > NOTICE: current transaction is aborted, queries ignored until end of transaction block > >>> db.query('commit') > >>> > > The notice was sent to stderr, it seems that I have no way to catch > it. There is getnotify(), but there is no getnotice(). I must catch > it, because my server must know if the operation was successful. (It > is in a multi-tier application's middle, and sends back a message > about the operation.) Using both the older 2.4 version of PyGreSQL and the newer 3.1 version that I am using you can catch these errors with a try/except block: db.query('BEGIN') try: db.query("INSERT INTO tbl(s) VALUES('value1')") except (pg.error,), detail: print "The transaction has been aborted\n %s" % (detail,) db.query('ABORT') #not necessary > Second problem: > > >>> lo = db.locreate(pg.INV_WRITE) > >>> lo > Closed large object, oid 18863 > >>> lo.open(pg.INV_WRITE) > Traceback (innermost last): > File "<stdin>", line 1, in ? > IOError: can't open large object. > >>> > > I have compiled the PyGreSQL module without -DNO_LARGE. You need to encapsulate your large object access in a transaction try starting with a: db.query('BEGIN') and ending it with: db.query('COMMIT') > Thank in advance: > > Laszlo Nagy > nagylzs@delfin.klte.hu I hope this helps. Jason -- The single most useful thing about the Internet is that it facilitates using Linux. To use Linux, you need so much goddamn technical information that if you don't have a really good source of technical support, you're just screwed. -- Neal Stephenson __________________________________________________ Do You Yahoo!? Get Yahoo! Mail Free email you can access from anywhere! http://mail.yahoo.com/ ^ permalink raw reply [nested|flat] 4+ messages in thread
* Re: PyGreSQL and transactions @ 2000-07-26 12:21 Nagy Laszlo Zsolt , KLTE TTK pm1 <nagylzs@dragon.klte.hu> parent: Billy G. Allie <Bill.Allie@mug.org> 0 siblings, 0 replies; 4+ messages in thread From: Nagy Laszlo Zsolt , KLTE TTK pm1 @ 2000-07-26 12:21 UTC (permalink / raw) To: Billy G. Allie <Bill.Allie@mug.org>; +Cc: pgsql-interfaces > > I'm writting a text-based server program with PyGreSQL. > > My first problem follows: ... > I have a Python to PostgreSQL interface program that I am preparing to release. ... > > I have been using the interface for about a week now without problems., but > have only been using it on UnixWare 7.0. If you are interested in using the > interface, I can send it to you and provide some assistance in porting it to > your environement (if needed). > Yes, I would be very pleased. :-) Laci 1.0 ^ permalink raw reply [nested|flat] 4+ messages in thread
end of thread, other threads:[~2000-07-26 12:21 UTC | newest] Thread overview: 4+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2000-07-20 10:14 PyGreSQL and transactions Nagy Laszlo Zsolt , KLTE TTK pm1 <nagylzs@dragon.klte.hu> 2000-07-20 22:07 ` Billy G. Allie <Bill.Allie@mug.org> 2000-07-26 12:21 ` Nagy Laszlo Zsolt , KLTE TTK pm1 <nagylzs@dragon.klte.hu> 2000-07-21 17:28 Re: PyGreSQL and transactions Jason Earl <jdearl@yahoo.com>
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