David Wayne Birdsall created TRAFODION-2729:
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Summary: Parallel plan not chosen for native HBase table
Key: TRAFODION-2729
URL: https://issues.apache.org/jira/browse/TRAFODION-2729
Project: Apache Trafodion
Issue Type: Bug
Components: sql-cmp
Affects Versions: 2.3-incubating
Environment: Probably all
Reporter: David Wayne Birdsall
If I have a Trafodion table salted into 2 partitions, I can induce a parallel
plan on that table using a cardinality hint. For example:
CREATE TABLE TRAFODION.SEABASE.ADEF
(
ROW_ID VARCHAR(100) CHARACTER SET ISO88591
COLLATE DEFAULT NO DEFAULT NOT NULL NOT DROPPABLE NOT SERIALIZED
, COLUMN_DETAILS VARCHAR(10000) CHARACTER SET ISO88591
COLLATE DEFAULT NO DEFAULT NOT NULL NOT DROPPABLE NOT SERIALIZED
, PRIMARY KEY (ROW_ID ASC)
)
SALT USING 2 PARTITIONS
ATTRIBUTES ALIGNED FORMAT
;
>>prepare s1 from select column_details,count(*)
+> from adef <<+ cardinality 1e8 >>
+> group by column_details;
--- SQL command prepared.
>>explain options 'f' s1;
LC RC OP OPERATOR OPT DESCRIPTION CARD
---- ---- ---- -------------------- -------- -------------------- ---------
4 . 5 root 2.00E+000
3 . 4 hash_partial_groupby 2.00E+000
2 . 3 esp_exchange 1:2(hash2) 2.00E+000
1 . 2 hash_partial_groupby 2.00E+000
. . 1 trafodion_scan ADEF 1.00E+008
--- SQL operation complete.
However, if I have a native HBase table split into two regions, the same
cardinality hint does not produce a parallel plan:
>>prepare s2 from select column_details,count(*)
+> from hbase."_ROW_"."def" <<+ cardinality 1e8 >>
+> group by column_details;
--- SQL command prepared.
>>explain options 'f' s2;
LC RC OP OPERATOR OPT DESCRIPTION CARD
---- ---- ---- -------------------- -------- -------------------- ---------
2 . 3 root 2.00E+000
1 . 2 hash_groupby 2.00E+000
. . 1 hbase_scan def 1.00E+008
--- SQL operation complete.
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