Will Oberman created CASSANDRA-4789:
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Summary: CassandraStorage.getNextWide produces corrupt data
Key: CASSANDRA-4789
URL: https://issues.apache.org/jira/browse/CASSANDRA-4789
Project: Cassandra
Issue Type: Bug
Components: Hadoop
Affects Versions: 1.1.5
Reporter: Will Oberman
This took me a while to track down. I'm seeing the problem when the "key
changes" case happens. The intended behavior (as far as I can tell) when the
key changes is the method returns the current tuple, and picks up where it left
off on the next call to getNextWide(). The problem I'm seeing is the sometimes
the current key advances between method calls, sometimes not. "Not" being the
correct behavior, since the code is saving the value into an instance variable,
but when the key advances there is a key/value mismatch (the result being the
values for two different keys are being glued together). I think the problem
might be related to keys that only have a single column??? I'm still trying to
track that down to help assist in solving this case...
Maybe this will be clearer from me pasting a bunch of logging I added to the
class. The log messages are fairly self documenting (I hope):
...lots of previous logging...
enter getNextWide
hasNext = true
set key = dVNhbXAxMzQ3ODM1OA%3D%3D
lastRow != null
added 1 items to bag from lastRow
added 1 items to bag from row
hasNext = true
added 1 items to bag from row
hasNext = true
added 1 items to bag from row
hasNext = true
added 1 items to bag from row
hasNext = true
added 1 items to bag from row
hasNext = true
added 1 items to bag from row
hasNext = true
added 1 items to bag from row
hasNext = true
added 1 items to bag from row
hasNext = true
key changed, new key = 669392df09572d0045b964bc65f86a2c
exit getNextWide
enter getNextWide
hasNext = true
//!!!THIS IS THE PROBLEM HERE I THINK!!!
//!!!Usually the key here == key before "exit getNextWide"!!!
set key = 5f900ee4bb1850f8cf387cc3d5fc23ca
//!!! lastRow is data for 669392df09572d0045b964bc65f86a2c !!!
//!!! but it's being added to key 5f900ee4bb1850f8cf387cc3d5fc23ca !!!
lastRow != null
added 1 items to bag from lastRow
//!!! Here are the real values for 5f900ee4bb1850f8cf387cc3d5fc23ca !!!
added 1 items to bag from row
hasNext = true
added 1 items to bag from row
hasNext = true
key changed, new key = 50438549-cdb6-8c44-f93a-d18d7daeffd8
exit getNextWide
enter getNextWide
hasNext = true
set key = 50438549-cdb6-8c44-f93a-d18d7daeffd8
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