DB2 - Problembeschreibung
Problem IT04157 | Status: Geschlossen |
PERFORMANCE MAY BE POOR FOR QUERIES WITH A VALUES CLAUSE AND UNION OPERATOR | |
Produkt: | |
DB2 FOR LUW / DB2FORLUW / A50 - DB2 | |
Problembeschreibung: | |
Queries involving a VALUES clause joined to a UNION or UNION ALL operation may experience poor performance. Affected queries may required fully reading the table referenced by the UNION or UNION ALL operator before applying the filtering offered by the VALUES clause. For example in the following query can exhibit this behaviour. select v.* from ( select c1, c2, c3 from ( select * from t1 union select * from t2 ) ) v, table( values (?, ?),(?, ?),(?, ?),(?, ?),(?, ?) ) as c(c1, c2) where v.c1 = c.c1 and v.c2 = c.c2; To determine if you are affected by this issue. Gather explain output for relevant queries and examine the db2exfmt output to see if the TFNUM_LINT table function is joined to the UNION result. | |
Problem-Zusammenfassung: | |
**************************************************************** * USERS AFFECTED: * * ALL * **************************************************************** * PROBLEM DESCRIPTION: * * See Error Description * **************************************************************** * RECOMMENDATION: * * Upgrade to DB2 LUW v10.5 fixpack 5. * **************************************************************** | |
Local-Fix: | |
Manually rewrite the query to push the values clause into each leg of the UNION operator. | |
Lösung | |
First fixed in DB2 LUW v10.5 fixpack 5. | |
Workaround | |
keiner bekannt / siehe Local-Fix | |
Weitere Daten | |
Datum - Problem gemeldet : Datum - Problem geschlossen : Datum - der letzten Änderung: | 03.09.2014 13.03.2015 13.03.2015 |
Problem behoben ab folgender Versionen (IBM BugInfos) | |
Problem behoben lt. FixList in der Version | |
10.5.0.5 |