[DRILL-7979] Self-Closing XML Tags Cause Schema Change Exceptions

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 1.19.0
• Fix Version/s: 1.20.0
• Component/s: Storage - Other
• Assignee: Charles Givre
• Reporter: Charles Givre
• Created: 02/Aug/21 03:20
• Updated: 22/Oct/21 14:28
• Resolved: 22/Oct/21 14:28

Description

Self closing XML tags are dealt with strangely by java's streaming parser.  If you have data where you have one row containing a self closing XML tag foo (<foo/>) but then in the next row `foo` contains a map or other nested field, Drill will throw a schema change exception.  

This proposed fix causes Drill to ignore self-closing tags unless they have attributes, which allows data like this to be successfully queried.