tree e446607bf014189805d78337f06cfab4d1aed58a
parent 09d4f9f404d043a073096179b889e8870590b9a8
author Yingyi Bu <yingyi@couchbase.com> 1464047065 -0700
committer Yingyi Bu <buyingyi@gmail.com> 1464053466 -0700

ASTERIXDB-1228: Add MISSING into the data model.

1. MISSING repsents the value of a non-existing field in a record
   or an out-of-bound index access of a collection;
2. NULL represents that the value of an optional field in a record
   is unknown or the value of existing collection entry is unknown.
3. Unit tests for all missing/null-in-missing/null-out scalar functions.

Change-Id: Ia49ed8474bfc5d6604231819065117468c5b0897
Reviewed-on: https://asterix-gerrit.ics.uci.edu/846
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Till Westmann <tillw@apache.org>