[ https://issues.jboss.org/browse/TEIID-4520?page=com.atlassian.jira.plugin... ] Ramesh Reddy commented on TEIID-4520: ------------------------------------- There is explicit NULL CONCAT null behavior, I believe we need to match to that. Like in Teiid we support two different types of CONCAT one does NULL and other does the value. We need to match Teiid function to the EXASOL function. The aim of system functions are, Teiid supports a variety of them, we need to figure out which ones are already supported by the source and if they do then try to match them so that they are pushed down to the source. If they need to be supplied more/different parameters you can use "function modifiers" to convert them to a required form before sending for execution. For example, some databases support LCASE whereas others support LOWERCASE, Teiid supports LCASE, so in the translator, you do name change of the function from LCASE to LOWERCASE. We have seen small subtle differences are always there but we need to minimize that, if the behavior is different you can choose to not support that function. If there are some functions that are not supported by Teiid that source supports, then add them as "pushDown" functions, that is the reason there are two types there. -- This message was sent by Atlassian JIRA (v7.5.0#75005)