[jira] [Work started] (TRAFODION-2777) Fix latent bug unmasked by JIRA TRAFODION-2765 fix

["David Wayne Birdsall (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/TRAFODION-2777?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Work on TRAFODION-2777 started by David Wayne Birdsall.
-------------------------------------------------------
> Fix latent bug unmasked by JIRA TRAFODION-2765 fix
> --------------------------------------------------
>
>                 Key: TRAFODION-2777
>                 URL: https://issues.apache.org/jira/browse/TRAFODION-2777
>             Project: Apache Trafodion
>          Issue Type: Bug
>          Components: sql-cmp
>    Affects Versions: 2.3-incubating
>         Environment: All
>            Reporter: David Wayne Birdsall
>            Assignee: David Wayne Birdsall
>
> The fix to JIRA TRAFODION-2765 unmasked another bug that causes regression test compGeneral/TEST006 to fail sometimes. The nature of the bug is that a query plan on a table with no statistics sometimes flips over to an MDAM plan where it wasn't before. One example of this that I saw happened in a release build while in a debug build the test passed.
> The following script (sometimes!) reproduces the bug:
> ?section setup
> create table t006t9 (a int not null primary key, b int, c int) salt using 2 partitions ;
> create index t006t9ix1 on t006t9(b) ;
> insert into t006t9 values (1,2,3), (10,20,30);
> prepare expl from
> select operator, cardinality,
>        cast(substring(description, position('scan_type: ' in description), position('object_type: ' in description) - position('scan_type: ' in description)) as char(100)) scan_type
> from table(explain(null, 'S'))
> where operator like '%SCAN%';
> ?section doit
> prepare s from
> select a,b from t006t9 <<+ index TRAFODION.SCH.T006T9IX1>> where b > 10;
> execute expl;



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