[ python-Bugs-788421 ] bsddb btree set_location() semantics changed

Tue Mar 16 02:59:33 EST 2004

Bugs item #788421, was opened at 2003-08-13 16:21
Message generated for change (Comment added) made by greg
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Category: Extension Modules
Group: Python 2.3
Status: Closed
Resolution: Fixed
Priority: 5
Submitted By: Gregory P. Smith (greg)
Assigned to: Gregory P. Smith (greg)
Summary: bsddb btree set_location() semantics changed

Initial Comment:
In the old bsddb module a bsddb.btopen(..) database
would return the next available key+value on a
set_location(key) call when key did not exist in the
database.  In python 2.3 (pybsddb) it raises an
exception and leaves the cursor at an unknown position
in the database.

[reported by Anthony McDonaly on comp.lang.python]

>>> import os
>>> import bsddb
>>> os.chdir(&#039;/tmp&#039;)
>>> my_data = bsddb.btopen(&#039;testing&#039;, &#039;c&#039;)
>>> for i in range(10):
...   if i == 5:
...     pass
...   else:
...     my_data[&#039;%d&#039;%i] = &#039;%d&#039;%(i*i)
...
>>> my_data.keys()
[&#039;0&#039;, &#039;1&#039;, &#039;2&#039;, &#039;3&#039;, &#039;4&#039;, &#039;6&#039;, &#039;7&#039;, &#039;8&#039;, &#039;9&#039;]
>>> my_data.sync()
>>> my_data.set_location(&#039;5&#039;)
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File
"/space/python-2.3/lib/python2.3/bsddb/__init__.py",
line 117, in set_location
    return self.dbc.set(key)
_bsddb.DBNotFoundError: (-30991, &#039;DB_NOTFOUND: No
matching key/data pair found&#039;)

Correct behaviour would have been to return (&#039;6&#039;, &#039;36&#039;)

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>Comment By: Gregory P. Smith (greg)
Date: 2004-03-15 23:59

Message:
Logged In: YES 
user_id=413

committed fix to head and release23-maint along with an associated fix for set_range where it could free() memory that it doesn't own on non B-Tree databases.

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Comment By: Gregory P. Smith (greg)
Date: 2004-02-26 02:11

Message:
Logged In: YES 
user_id=413

Yes this is a bug.  The set_location() method should have been calling set_range() rather than set() internally.

Fixing that exposed another bug: set_range() would crash when looking up a key that exists in hash or rn databases.

Both bugs have been fixed to fix this one in python 2.4 & pybsddb CVS.

This bugfix should go into python 2.3.4.

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