tree e584a66d398129124880e35e657de0476d83cca2
parent 618bd05dc9e878aaf1c2e7a688aee71465e9dec1
author Ali Alsuliman <ali.al.solaiman@gmail.com> 1554793080 -0700
committer Ali Alsuliman <ali.al.solaiman@gmail.com> 1554838237 -0700

[ASTERIXDB-2516][RT] Modifty range map function of parallel sort

- user model changes: no
- storage format changes: no
- interface changes: no

Details:
Currently, the range map function of parallel sort passes "null"
to get a comparator to sort the samples and produce the range map.
The comparator provider will enforce providing a type and prevent
passing "null". The range map function needs to be updated to get
the types of the sort fields and use them to get comparators.
- changed the output type of the local sampling function from
list of list of ANY to binary. The old type computer was removed.
- added null writer aggregate function that just produces null as
an aggregate value. this is needed in order to propagate the type
of the sort fields from the local step to the global step so that
the range map function can know the types of the sort fields.

Change-Id: I7edbb10906cc4464210af87a5b1630ba3aecbde0
Reviewed-on: https://asterix-gerrit.ics.uci.edu/3333
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Contrib: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Dmitry Lychagin <dmitry.lychagin@couchbase.com>