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https://issues.apache.org/jira/browse/TRAFODION-321?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Atanu Mishra closed TRAFODION-321.
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Resolution: Fixed
Assignee: (was: Apache Trafodion)
Fix Version/s: 0.8 (pre-incubation)
> LP Bug: 1324303 - bad cardinality estimates for metadata queries
> ----------------------------------------------------------------
>
> Key: TRAFODION-321
> URL: https://issues.apache.org/jira/browse/TRAFODION-321
> Project: Apache Trafodion
> Issue Type: Bug
> Components: sql-cmp
> Reporter: Apache Trafodion
> Priority: Critical
> Fix For: 0.8 (pre-incubation)
>
>
> cardinality estimation for metadata queries is not correct. Specifically for
> the case of an index join and the join is on the index column. The
> cardinality of the join should reflect that of the left child of the join.
> Example of a metadata table that has the issue:
> prepare st1 from select T.CONSTRAINT_TYPE, o.OBJECT_NAME from
> trafodion."_MD_".table_constraints T, trafodion."_MD_".objects O where
> T.table_uid = o.object_uid;
> >>explain options 'f' st1;
> LC RC OP OPERATOR OPT DESCRIPTION CARD
> ---- ---- ---- -------------------- -------- -------------------- ---------
> 3 . 4 root 5.00E+003
> 2 1 3 hybrid_hash_join 5.00E+003
> . . 2 trafodion_index_scan OBJECTS 1.00E+002
> . . 1 trafodion_scan TABLE_CONSTRAINTS 1.00E+002
> --- SQL operation complete.
> >>
> Assigned to LaunchPad User taoufik ben abdellatif
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