Mark Addleman created TEIID-3062: ------------------------------------ Summary: Apply LIMIT 1 optimization for DISTINCT in UNION situations Key: TEIID-3062 URL: https://issues.jboss.org/browse/TEIID-3062 Project: Teiid Issue Type: Feature Request Security Level: Public (Everyone can see) Components: Query Engine Affects Versions: 8.1 Reporter: Mark Addleman Assignee: Steven Hawkins The translator does not support select expressions. Query: SELECT DISTINCT DATAMART_NAME AS c_9, '_constant_' AS c_10 FROM (SELECT datamart_name FROM ( SELECT 'DATACOM Datamart' AS DATAMART_NAME FROM SECURITY_DM_DATACOM_DEV_R140_CA31_CMGRD1.VIEWOBJACCESS UNION ALL SELECT 'DB2 D91A Datamart' AS DATAMART_NAME FROM SECURITY_DM_DB2_D91APTIB_CMGRD1.VIEWOBJACCESS ) AS t ) a Final part of plan: OPTIMIZATION COMPLETE: PROCESSOR PLAN: SortNode(0) output=[datamart_name AS c_9, '_constant_' AS c_10] [DUP_REMOVE] ProjectNode(1) output=[datamart_name AS c_9, '_constant_' AS c_10] [datamart_name AS c_9, '_constant_' AS c_10] UnionAllNode(2) output=[datamart_name] AccessNode(3) output=['DATACOM Datamart' AS DATAMART_NAME] SELECT 'DATACOM Datamart' FROM SECURITY_DM_DATACOM_DEV_R140_CA31_CMGRD1.VIEWOBJACCESS AS g_0 AccessNode(4) output=['DB2 D91A Datamart' AS DATAMART_NAME] SELECT 'DB2 D91A Datamart' FROM SECURITY_DM_DB2_D91APTIB_CMGRD1.VIEWOBJACCESS AS g_0 Expected LIMIT 1 in the access nodes. Comment from Steven: "More than likely we are not checking across a union for this optimization." See https://community.jboss.org/message/883460 for more details and complete plan -- This message was sent by Atlassian JIRA (v6.2.6#6264)