[teiid-issues] [JBoss JIRA] (TEIID-1870) Querying random number from DB2 v97 does not push down to source

[Paul Nittel (Created) (JIRA)]

Querying random number from DB2 v97 does not push down to source
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                 Key: TEIID-1870
                 URL: https://issues.jboss.org/browse/TEIID-1870
             Project: Teiid
          Issue Type: Bug
          Components: Query Engine
    Affects Versions: 7.6
            Reporter: Paul Nittel
            Assignee: Steven Hawkins


When I query SELECT RAND(), IntKey from SmallA using DB2 directly, I get back:
1,INTKEY
0.00125,0
0.56359,1
0.1933,2
0.80874,3

Using the equivalent SQL through Teiid to DB2, I get:
expr,IntKey
0.86867,0
0.86867,1
0.86867,2
0.86867,3

The command log entry for the Teiid query looks like this:
2011-12-14 07:50:22,093 DEBUG [org.teiid.COMMAND_LOG] (New I/O server worker #1-2         START USER COMMAND:        startTime=2011-12-14 07:50:22.093        requestID=KURKVzpMf/MI.12        txID=null        sessionID=KURKVzpMf/MI        applicationName=JDBC        principal=user at teiid-security        vdbName=QT_db2v97ds_Push        vdbVersion=1        sql=select rand(), curtime(), intkey from bqt1.smalla limit 5
2011-12-14 07:50:22,099 DEBUG [org.teiid.COMMAND_LOG] (Worker6_QueryProcessorQueue1394         START DATA SRC COMMAND:        startTime=2011-12-14 07:50:22.098        requestID=KURKVzpMf/MI.12        sourceCommandID=0        txID=null        modelName=Source        connectorBindingName=db2        sessionID=KURKVzpMf/MI        principal=user at teiid-security        sql=SELECT convert(g_0.INTKEY, integer) AS c_2 FROM Source.SMALLA AS g_0 LIMIT 5
2011-12-14 07:50:22,394 DEBUG [org.teiid.COMMAND_LOG] (Worker6_QueryProcessorQueue1396         END SRC COMMAND:        endTime=2011-12-14 07:50:22.394        requestID=KURKVzpMf/MI.12        sourceCommandID=0        txID=null        modelName=Source        connectorBindingName=db2        sessionID=KURKVzpMf/MI        principal=user at teiid-security        finalRowCount=5
2011-12-14 07:50:22,427 DEBUG [org.teiid.COMMAND_LOG] (Worker5_QueryProcessorQueue1397         END USER COMMAND:        endTime=2011-12-14 07:50:22.427        requestID=KURKVzpMf/MI.12        txID=null        sessionID=KURKVzpMf/MI        principal=user at teiid-security        vdbName=QT_db2v97ds_Push        vdbVersion=1        finalRowCount=0

The source command appears to be lacking the rand() function call. 

In response, dev says, "So the issue here is that the final rewrite of the pushdown query is pre-evaluating the non-deterministic pushdown function.  If the function were not pushed-down you would get something more like you would expect."

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