Using online Migration to migrate CCM server from 4.x to 5.x can result in corruption of streams and workspaces

Symptom

• Online migration logs may contain exception stack traces indicating transient SQL exceptions occurred during migration.
  
  The addTables migration log may indicate that less than 100% of items were processed:
  
  
2015-02-28 00:44:19,959 CRJAZ2693I Running online migration on 389,576 item states. 385,141 previously processed. 2 new type handlers.
2015-02-28 00:44:19,960 Type "ChangeHistory", 150,816 of 153,434 item status previously processed.
2015-02-28 00:44:19,960 Type "HistoricBasis", 234,325 of 236,142 item status previously processed.
2015-02-28 00:44:27,873 Status: 385,192 of 389,576 processed (98% complete). Estimated completion time: 2/28/15 12:45 AM.
2015-02-28 00:44:30,988 CRJAZ2691I No more items to process.
2015-02-28 00:44:31,001 CRJAZ2739I No state migration failures occurred during online migration.

  
  
• The migrated server may have active FilesystemService.compareWorkspaces service calls that are hung and running for hours or days.
  
  
• Workspaces or Streams may contain gaps in recent history. Users may receive unexpected gap messages when trying to accept or deliver.
  
  
• When attempting to accept or deliver changes users may receive error messages similar to
  
  Internal problem: change sets for /component/example/file.txt have null common ancestor.
  
  or
  
  Internal problem: change sets yielded null common ancestor.