[ZODB-Dev] ReadConflictError while re-indexing big fat index
Roché Compaan
roche at upfrontsystems.co.za
Mon Aug 2 09:47:48 EDT 2004
Chris Withers wrote:
> Roché Compaan wrote:
>
>>> ReadConflictError: database read conflict error (oid
>>> 000000000001ff36, class BTrees.IIBTree.IISet)
>>>
>>> 1. What is the above error message really trying to tell me?
>>> (it's a pretty obscure message ;-)
>>
>>
>> An object (most probably the index) was modified and thus invalidated
>> in another transaction. At the time that your indexing operation wants
>> to commit, the ZEO server tells you that your are trying to modify an
>> object that has been invalidated.
>
>
> I'm not sure that is correct. Sounds like you're describing a Write
> ConflictError. I'm experiencing a ReadConflictError on the web serving
> side of the equation, where no writing is being done...
>
I have some wires crossed :-\ Last week I ordered "pee yellow" bricks
(as my wife put it) instead of red ones. Must be because I stopped smoking.
Anyway, if I'm not mistaken, a ReadConflict will occur if an object is
invalidated after it was loaded by the client. Inside
Connection.setstate's you'll see this comment:
# Avoid reading data from a transaction that committed
# after the current transaction started, as that might
# lead to mixing of cached data from earlier transactions
# and new inconsistent data.
--
Roché Compaan
Upfront Systems http://www.upfrontsystems.co.za
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