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Posted to issues@trafodion.apache.org by "David Wayne Birdsall (JIRA)" <ji...@apache.org> on 2018/08/13 21:07:00 UTC
[jira] [Closed] (TRAFODION-2729) Parallel plan not chosen for
native HBase table
[ https://issues.apache.org/jira/browse/TRAFODION-2729?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
David Wayne Birdsall closed TRAFODION-2729.
-------------------------------------------
> 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
> Environment: Probably all
> Reporter: David Wayne Birdsall
> Assignee: David Wayne Birdsall
> Priority: Major
> Fix For: 2.3
>
>
> 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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