[Pypgsql-devel] [ pypgsql-Bugs-589370 ] PgSQL.py hangs on empty result

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Bugs item #589370, was opened at 2002-07-31 23:03
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=116528&aid=589370&group_id=16528

Category: PgSQL
Group: None
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Nobody/Anonymous (nobody)
Assigned to: Gerhard Häring (ghaering)
Summary: PgSQL.py hangs on empty result

Initial Comment:
PACKAGE:
pyPgSQL 2.1 (and in 2.0 too) Win32

USING:
python 2.2 (Win32)
Server 7.1.2 Mandrake Linux 8.1

ERROR:
PgSQL.py hangs on line 2142 on empty result.

SEE DETAILS IN ATTACHED FILE!

select 
b.Bitrate,b.DauerTxt,b.Dauer,b.OID,b.Artist,a.Name,a.OI
D,b.Track,b.Genre,       
a.PlayList,a.Kommentar,b.Jahr,b.ImportStamp,a.Item,b.
Album,a.Entry,b.Title,b.Filename
from PlayLists as a,AlleTitel as b
where a.Entry=b.OID and (a.PlayList=1 and a.Item>=0)
order by a.Item

###############################################
########
This results in the following error (Notice: There are the 
OIDs of both files selected!)

Traceback (most recent call last):
  File "jukebox.py", line 476, in ?
    main()
  File "jukebox.py", line 472, in main
    myApp = App()
  File "jukebox.py", line 27, in __init__
    wxApp.__init__(self,0)
  File "C:\Programme\python22\lib\site-
packages\wxPython\wx.py", line 1587, in __init__
    _wxStart(self.OnInit)
  File "jukebox.py", line 38, in OnInit
    self.readPlaylist()
  File "jukebox.py", line 296, in readPlaylist
    self.tbPtitles.readTitles(playlist)
  File "jukedb.py", line 271, in readTitles
    return self.readMore(where=wcls, order="a.Item")
  File "sqldb.py", line 228, in readMore
    cursor.execute(query)
  File "C:\PROGRA~1\Python22\Lib\site-
packages\pyPgSQL\PgSQL.py", line 2415, in execute
    self.__makedesc__()
  File "C:\PROGRA~1\Python22\Lib\site-
packages\pyPgSQL\PgSQL.py", line 2142, in 
__makedesc__
    _p = _res.getvalue(0, _i)
ValueError: result does not contain any tuples.

----------------------------------------------------------------------

>Comment By: Gerhard Häring (ghaering)
Date: 2002-08-03 08:05

Message:
Logged In: YES 
user_id=163326

Fixed in revision 1.13 of PgSQL.py.

----------------------------------------------------------------------

Comment By: Gerhard Häring (ghaering)
Date: 2002-08-02 10:52

Message:
Logged In: YES 
user_id=163326

I'm uploading a patch that is most likely all that's
required to fix this bug (and it wasn't PostgreSQL's fault,
which I was too quick to blame).

----------------------------------------------------------------------

Comment By: Gerhard Häring (ghaering)
Date: 2002-08-02 10:27

Message:
Logged In: YES 
user_id=163326

I could produce a very minimal test case (see upload).

Looks like a PostgreSQL bug that we have to work around: if
OID is in the select statement, and the query doesn't
produce any rows (_res.ntuples == 0), then _res.nfields != 0
because PostgreSQL says that it has returned an OID value,
which it hasn't :-/

That's at least my interpretation for now.

----------------------------------------------------------------------

Comment By: Nobody/Anonymous (nobody)
Date: 2002-08-01 22:34

Message:
Logged In: NO 

ERROR REPORT 31.07.2002 22:15 By Frank H. Raschke  
fr...@nk...

Hello!

I have some problems with pyPgSQL i'd like to mention:

PACKAGE:
pyPgSQL 2.1 (and in 2.0 too) Win32

USING:
python 2.2 (Win32)
Server 7.1.2 Mandrake Linux 8.1

ERROR:
PgSQL.py hangs on line 2142 on empty result.

###################################################
####
DETAILS: The following Tables where created by a script 
using pgsql:

CREATE TABLE "alletitel" (
	"dauer" double precision NOT NULL,
	"dauertxt" character varying(10) NOT NULL,
	"title" character varying(150) NOT NULL,
	"genre" character varying(40) NOT NULL,
	"artist" character varying(150) NOT NULL,
	"album" character varying(150) NOT NULL,
	"bitrate" double precision NOT NULL,
	"jahr" character(4) NOT NULL,
	"track" integer NOT NULL,
	"filename" character varying(250) NOT NULL,
	"importstamp" timestamp with time zone NOT 
NULL
);

CREATE INDEX alletitel_artist ON alletitel (artist);
CREATE INDEX alletitel_artisttitle ON alletitel (artist,title);
CREATE INDEX alletitel_title ON alletitel (title);

CREATE TABLE "playlists" (
	"playlist" integer NOT NULL,
	"item" integer NOT NULL,
	"name" character varying(40) NOT NULL,
	"kommentar" character varying(250) NOT NULL,
	"entry" integer NOT NULL
);

CREATE INDEX playlists_playlistitem ON playlists 
(playlist,item);

###################################################
####
The following statement was executed  by "cursor.execute
(statement)" where
"alletitel" contained some rows but "playlists" was empty and 
so the result was
of course empty too (important!)

select 
b.Bitrate,b.DauerTxt,b.Dauer,b.OID,b.Artist,a.Name,a.OID,b.Tr
ack,b.Genre,

a.PlayList,a.Kommentar,b.Jahr,b.ImportStamp,a.Item,b.Album
,a.Entry,b.Title,b.Filename
from PlayLists as a,AlleTitel as b
where a.Entry=b.OID and (a.PlayList=1 and a.Item>=0)
order by a.Item

The real Source won't help you much, I think, because this 
statement is generated
by the wrapper sqldb.py. The thing above is taken from 
a "print" of the query string.
Identical query wors fine with mySQL...

But if it helps, I can send you the little jukebox-app, but how 
can I do so ? Should I submit new ? Here I can't upload 
anymore....

###################################################
####
This results in the following error (Notice: There are the OIDs 
of both tables selected!)

Traceback (most recent call last):
  File "jukebox.py", line 476, in ?
    main()
  File "jukebox.py", line 472, in main
    myApp = App()
  File "jukebox.py", line 27, in __init__
    wxApp.__init__(self,0)
  File "C:\Programme\python22\lib\site-
packages\wxPython\wx.py", line 1587, in __init__
    _wxStart(self.OnInit)
  File "jukebox.py", line 38, in OnInit
    self.readPlaylist()
  File "jukebox.py", line 296, in readPlaylist
    self.tbPtitles.readTitles(playlist)
  File "jukedb.py", line 271, in readTitles
    return self.readMore(where=wcls, order="a.Item")
  File "sqldb.py", line 228, in readMore
    cursor.execute(query)
  File "C:\PROGRA~1\Python22\Lib\site-
packages\pyPgSQL\PgSQL.py", line 2415, in execute
    self.__makedesc__()
  File "C:\PROGRA~1\Python22\Lib\site-
packages\pyPgSQL\PgSQL.py", line 2142, in __makedesc__
    _p = _res.getvalue(0, _i)
ValueError: result does not contain any tuples.

###################################################
####

Thank You
Bye

----------------------------------------------------------------------

Comment By: Gerhard Häring (ghaering)
Date: 2002-08-01 09:08

Message:
Logged In: YES 
user_id=163326

I can't reproduce the problem here with PostgreSQL 7.2.1,
but will try later with a 7.1.3 at home. It'd still be ueful
if you could upload your schema and code.

----------------------------------------------------------------------

Comment By: Gerhard Häring (ghaering)
Date: 2002-08-01 08:55

Message:
Logged In: YES 
user_id=163326

Thanks for your submission. Your attachment wasn't uploaded. Most
probably you forgot to activate the checkbox titled "Check to
Upload and Attach a File".

This is a Sourceforge annoyance that we can do nothing about.
Would you please upload your file again? Thanks.

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=116528&aid=589370&group_id=16528