[teiid-issues] [JBoss JIRA] (TEIID-2188) When using CONCAT2(x, y), can the source query be changed to not include the CASE statements and let Oracle do the NULL compare

[Van Halbert (JIRA)]

Van Halbert created TEIID-2188:
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             Summary: When using CONCAT2(x, y), can the source query be changed to not include the CASE statements and let Oracle do the NULL compare
                 Key: TEIID-2188
                 URL: https://issues.jboss.org/browse/TEIID-2188
             Project: Teiid
          Issue Type: Enhancement
          Components: Embedded
    Affects Versions: 7.4.4
            Reporter: Van Halbert
            Assignee: Steven Hawkins


When CONCAT2(x, y) is used, the rewritten query is very verbose in adding a CASE statement to check for nulls.  Can the rewritten query not include the CASE statements and just let Oracle do the compare, because it can do it more efficiently within the CONCAT call?

Example:

select concat2(f1,f2) from table1

results in

SELECT c_0 FROM (SELECT CASE WHEN to_char(g_0.f1) IS NULL AND g_0.f2 IS NULL THEN NULL ELSE concat(nvl(to_char(g_0.f1), ''), nvl(g_0.f2, '')) END AS c_0 FROM table1 g_0)

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