[TRAFODION-2707] count(*) scans single region when it runs in parallel

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Affects Version/s: 2.2.0
• Component/s: sql-cmp
• Environment: All
• Assignee: Unassigned
• Reporter: fanglinghe
• Created: 10/Aug/17 13:38
• Updated: 10/Aug/17 13:38

Description

count executes in parallel but with a lower scanning cost in single region.

reproduce steps:
1> CREATE TABLE TRAFODION.BULKLOAD.TEST_A
(
A INT NO DEFAULT NOT NULL NOT DROPPABLE NOT
SERIALIZED
, B INT NO DEFAULT NOT NULL NOT DROPPABLE NOT
SERIALIZED
, C INT NO DEFAULT NOT NULL NOT DROPPABLE NOT
SERIALIZED
, D INT NO DEFAULT NOT NULL NOT DROPPABLE NOT
SERIALIZED
, PRIMARY KEY (A ASC, B ASC, C ASC, D ASC)
)
SALT USING 8 PARTITIONS
ON (A)
ATTRIBUTES ALIGNED FORMAT
;
2>explain select count from test_a <<+ cardinality 1e7>> where a = 1;