[teiid-issues] [JBoss JIRA] (TEIID-3227) Add support for sub-expression pushing of must pushdown functions

[ https://issues.jboss.org/browse/TEIID-3227?page=com.atlassian.jira.plugin... ] Steven Hawkins edited comment on TEIID-3227 at 11/24/14 12:19 PM: ------------------------------------------------------------------ Detecting this is also a little different than the existing must pushdown logic in RuleAssignOutputElements in that we're actually dealing with the grouping node and not a project node when this determination needs to be made. Although we could rationalize this by inserting an explicit project node, rather than the current logic in the grouping processing node that performs the necessary projection. was (Author: shawkins): If the function is deterministic, then it's valid to create the pushdown form but we would need to add an aggregate such as first/last or add the function to the grouping (although that wouldn't quite be correct for rollups). So more than likely this would look like: SELECT AAA, SUM(first\(x)) AS BBB_ALIAS FROM (select AAA, custom_function(BBB) as x from some_table WHERE some_table.CCC = 'VAL') as v GROUP BY AAA ORDER BY AAA Detecting this is also a little different than the existing must pushdown logic in RuleAssignOutputElements in that we're actually dealing with the grouping node and not a project node when this determination needs to be made. Although we could rationalize this by inserting an explicit project node, rather than the current logic in the grouping processing node that performs the necessary projection. -- This message was sent by Atlassian JIRA (v6.3.8#6338)