[jira] [Created] (UIMA-4100) deserialization of delta CASes broken in some cases

["Marshall Schor (JIRA)" <de...@uima.apache.org>]

Marshall Schor created UIMA-4100:
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             Summary: deserialization of delta CASes broken in some cases
                 Key: UIMA-4100
                 URL: https://issues.apache.org/jira/browse/UIMA-4100
             Project: UIMA
          Issue Type: Bug
          Components: Core Java Framework
    Affects Versions: 2.6.0SDK
            Reporter: Marshall Schor
            Assignee: Marshall Schor
             Fix For: 2.7.0SDK


Delta CAS serialization includes attempting to handle changes made by a remote "below the line" - changing existing FSs.   If the remote removes the FSs and re-adds them back to the indices, this fact is sent back with the delta CAS as a list of FSs that are "re-indexed".  The deserialization takes this list, and removes them, and re-adds them back to the indices in an attempt to get them properly indexed.  However, this doesn't reliably work, if any of the keys used in the indexing were updated. 

Furthermore, there is nothing that insures a remote remove/add FSs it is modifying.  Perhaps the remote is unaware that FSs of that type are even being indexed (the information about what indices are defined at the client is not sent to the remote). 

So, it is possible that the remote could modify some feature, which is used as a key by the client.   The Deserialization would update that feature, without removing the FS from the indices first.

One conclusion - the list of "re-indexed" FSs returned by the remote during a delta serialization is not a reliable indication of which FSs would need reindexing, since the index definitions between the client and the remote could be different.

A proper fix would be to check if an existing feature being updated was used as a key in any index at the client, before updating it, and remove it before updating the feature, and then add it back. 

This would require, if Delta CAS was being used, setting up the mechanisms proposed in UIMA-4059 to see if when deserializing some changes to existing FSs, whether or not changes were being made to features that were being used as keys in any index *and* the FS being modified was "added-to-indexes". 



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