[teiid-issues] [JBoss JIRA] (TEIID-5296) With MongoDB, timestamp operations throw exceptions when called on null values

[Jan Martiska (JIRA)]

Jan Martiska created TEIID-5296:
-----------------------------------

             Summary: With MongoDB, timestamp operations throw exceptions when called on null values
                 Key: TEIID-5296
                 URL: https://issues.jboss.org/browse/TEIID-5296
             Project: Teiid
          Issue Type: Bug
          Components: Misc. Connectors
            Reporter: Jan Martiska
            Assignee: Steven Hawkins


When a query contains timestamp operations like {{DAYOFMONTH}}, {{DAYOFWEEK}},.. and these are executed when some cells contain null (or missing field), MongoDB throws an exception. This exception is not handled by Teiid in any way and will fail the whole VDB query:

{noformat}
Remote com.mongodb.CommandFailureException: 
{ "serverUsed" : "localhost:27017" , 
"ok" : 0.0 , "errmsg" : "can't convert from BSON type null to Date" , 
"code" : 16006 , "
codeName" : "Location16006"}
{noformat}

Perhaps Teiid could work around this somehow so that the VDB query will not fail and affected cells will contain null in the result?

For example, this Mongo aggregation pipeline which extracts hours from timestamps:
{noformat}
db.collection.aggregate([
  { 
    $project : {
      hour: {$hour: "$DATEVALUE"}
    }
  }
])
{noformat}

could be transformed to this:
{noformat}
db.collection.aggregate([
  { 
    $project : {
      hour: { $cond: 
        [ { $or: [ 
                   { $eq: [ "$DATEVALUE", null ] }, 
                   { $eq: [ { $type: "$DATEVALUE" }, "missing" ] }                                       
                 ]
          },
          null, 
          { $hour: "$DATEVALUE" } 
        ] 
      }
    }
  }
])
{noformat}
after this transformation, the {{hour}} field will be null as expected for documents where {{DATEVALUE}} is null or missing completely




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