commit 77450e6a1ad081d2dc2d00b2847f45d8b9a407e5
author Ali Alsuliman <ali.al.solaiman@gmail.com> Wed Jun 05 18:44:09 2019 -0700
committer Ali Alsuliman <ali.al.solaiman@gmail.com> Thu Jun 06 21:25:22 2019 +0000
tree 4fa59c6eb557a1448cf850b57e1a50578f289b40
parent cdcb9235ae6d1e6d66d4c6d57de5098090e3996c

[ASTERIXDB-2574][COMP] Fix min/max functions

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

This change is mainly for 2 things. The first thing is to not throw
an exception when the type of the aggregated field is invalid for min/max
(e.g. record or rectange) or min/max get incompatible data like string
and int. The result in this case would be NULL. The second thing is to
enable comparing ARRAYs correctly by using logical comparison. When
a partition runs into type invalidity, it will output NULL. The global
aggregator interprets NULL received from a partition as type invalidity
and outputs NULL as the final result. Both SQL and SQL++ will do that.
Special treatment is needed for scalar and distinct version of SQL since
SQL min/max ignores NULL values and continue aggregation and the scalar
and distinct version of SQL are normally setup as a global aggregator
since they behave like the global aggregator in a two-step aggregation.
Currently, there is only a local min and max functions. The other
min/max functions are used for everything, the global function of
two-step aggregation, and for scalar and distinct min/max. In order to
differentiate, a global min/max functions are added that will be used
for the two-step aggregation.

Details:
- fixed listify to open up elements when adding them to the collection
and the collection item type is of type ANY and changed the type inferer
of listify to enable that.
- fixed AbstractCollectionType to make sure itemType is never null.
- changed MinMaxAggTypeComputer to not throw an exception but return
NULL for invalid types.
- changed min/max descriptors to implement inferer to propagate the
type of the field and pass that when getting a comparator.
- switched min/max comparison to the logical comparison.
- refactored method inequalityUndefined to be shared by logical comparison
and min/max functions.
- added global max/min functions to enable differentiating between
scalar min/max, distinct min/max and two-step min/max (global & local).
- code clean-up for LogicalScalarBinaryComparator; created two INSTANCES
and re-used.

Change-Id: I1231cfe558099d167bae0b2fa7fc4879b756baf0
Reviewed-on: https://asterix-gerrit.ics.uci.edu/3427
Contrib: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Tested-by: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Integration-Tests: Jenkins <jenkins@fulliautomatix.ics.uci.edu>
Reviewed-by: Dmitry Lychagin <dmitry.lychagin@couchbase.com>