[teiid-issues] [JBoss JIRA] (TEIID-1899) Getting Assertion when running Inner Merge Join query with SELECT COUNT(*) on top

[Steven Hawkins (JIRA)]

     [ https://issues.jboss.org/browse/TEIID-1899?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Steven Hawkins resolved TEIID-1899.
-----------------------------------

    Fix Version/s: 7.6.1
                   8.0
       Resolution: Done


The issue is that distinct dependent tuple buffers are being removed (previously a new tuplebuffer was always created regardless of whether the distinct operation was needed or not).

Note that this issue was also partially due to the dependent join backoff logic, since that was triggering a normal handling of the effective semi-join.  7.4.x may also benefit from change r3780 that more narrowly applies the backoff logic to only when column ndv values are known.

I noticed a TODO in that we could be doing a better value of sharing potentially distinct sorted independent results with the dependent join logic.  For a non-enhanced merge, currently both the dependent join and the criteria handling logic will perform a sort.
                
> Getting Assertion when running Inner Merge Join query with SELECT COUNT(*) on top
> ---------------------------------------------------------------------------------
>
>                 Key: TEIID-1899
>                 URL: https://issues.jboss.org/browse/TEIID-1899
>             Project: Teiid
>          Issue Type: Bug
>          Components: Query Engine
>    Affects Versions: 7.4.1
>            Reporter: Van Halbert
>            Assignee: Steven Hawkins
>             Fix For: 7.6.1, 8.0
>
>         Attachments: oracle11-ds.xml, postgres-8.4-tpcr01-ds.xml, server_with_error.log, TPC.vdb
>
>
> When running the following query, it causing an ASSERTION (see attached log):
> SELECT COUNT(*) AS CNT FROM (SELECT ORDERS.O_ORDERKEY, ORDERS.O_ORDERDATE, ORDERS.O_CLERK, CUSTOMER.C_CUSTKEY, CUSTOMER.C_NAME, CUSTOMER.C_ACCTBAL 
> FROM TPCR01_PostgreSQLVirt.ORDERS, TPCR01_OracleVirt.CUSTOMER WHERE (CUSTOMER.C_CUSTKEY = ORDERS.O_CUSTKEY) AND 
> (ORDERS.O_ORDERDATE < '1992-01-05 00:00:00') AND (CUSTOMER.C_ACCTBAL < 9514.5)) AS T
> Note:  this doesn't fail when SELECT COUNT(*) isn't used

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