Python DBAPI driver throws exception when fetching EXPLAIN results

[monetdb-team]

Date: 2013-10-03 10:25:33 +0200
From: Pete Hollobon <>
To: clients devs <>
Version: 11.15.15 (Feb2013-SP4)
CC: pete

Last updated: 2013-10-22 14:42:10 +0200

Comment 19234

Date: 2013-10-03 10:25:33 +0200
From: Pete Hollobon <>

User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/29.0.1547.76 Safari/537.36
Build Identifier:

The Python DBAPI driver throws an exception when fetching EXPLAIN query results:

Python 2.7.3 (default, Sep 26 2012, 21:51:14)
[GCC 4.7.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.

import monetdb.sql
db = monetdb.sql.connect(database="demo")
cursor = db.cursor()
cursor.execute("explain select count(*) from sys.tables")
31
cursor.fetchone()
Traceback (most recent call last):
File "", line 1, in
File "monetdb/sql/cursors.py", line 205, in fetchone
result = self.__rows[self.rownumber - self.__offset]
IndexError: list index out of range

I've attached patches that fix this issue for both Python 2 and 3 versions of the driver, so it works as expected:

import monetdb.sql
db = monetdb.sql.connect(database="demo")
cursor = db.cursor()
cursor.execute("explain select count(*) from sys.tables")
31
cursor.fetchone()
('function user.s0_14():void;',)
cursor.fetchone()
(' X_2:bat[:oid,:wrd] := bat.new(nil:oid,nil:wrd);',)

Thanks,
Pete.

Reproducible: Always

Comment 19235

Date: 2013-10-03 10:26:17 +0200
From: Pete Hollobon <>

Created attachment 239
Python 2 fix

Attached file: file_3380.txt (text/plain, 1186 bytes)
Description: Python 2 fix

Comment 19236

Date: 2013-10-03 10:29:59 +0200
From: Pete Hollobon <>

Created attachment 240
Python 3 fix

Attached file: file_3380.txt (text/plain, 1106 bytes)
Description: Python 3 fix

Comment 19237

Date: 2013-10-03 10:53:08 +0200
From: MonetDB Mercurial Repository <>

Changeset 119925c03cba made by Sjoerd Mullender sjoerd@acm.org in the MonetDB repo, refers to this bug.

For complete details, see http//devmonetdborg/hg/MonetDB?cmd=changeset;node=119925c03cba

Changeset description:

Added test for bug #3380.

Comment 19238

Date: 2013-10-03 10:53:10 +0200
From: MonetDB Mercurial Repository <>

Changeset c4693598a20e made by Sjoerd Mullender sjoerd@acm.org in the MonetDB repo, refers to this bug.

For complete details, see http//devmonetdborg/hg/MonetDB?cmd=changeset;node=c4693598a20e

Changeset description:

Fixed bug #3380.
Thanks to Pete Hollobon for finding and fixing the bug.