DB2 - Problembeschreibung
Problem IC71343 | Status: Geschlossen |
NEW FEATURE ADDED IN V95 TO BETTER SERVE MOST FETCH FIRST N ROWS (FFNR) QUERIESCAUSING REGRESSION ON CERTAIN QUERY | |
Produkt: | |
DB2 FOR LUW / DB2FORLUW / 950 - DB2 | |
Problembeschreibung: | |
New feature added in v95 to better serve most FFNR queries causing regression on certain query. The new query plan is 2 to 3 times slower. Query: select productkey from product where lot_id = 'HE.9119.FHA.BBWP2ZJ' or lotlabel = 'HE.9119.FHA.BBWP2ZJ' fetch first 1 rows only with ur In v95, optimizer generates the plan below: Access Plan: ----------- Total Cost: 873.854 Query Degree: 1 Rows RETURN ( 1) Cost I/O | 2 DTQ ( 2) 873.854 863.469 | 1 TBSCAN ( 3) 2278.03 2251 | 25044 TABLE: DB2INST1 PRODUCT Q1 In v91, the query plan: ------------------------------- Total Cost: 52.9793 Query Degree: 1 Rows RETURN ( 1) Cost I/O | 4.18866 DTQ ( 2) 52.9793 7 | 2.09433 FETCH ( 3) 52.9593 7 /---+---\ 2.09433 1.14541e+06 RIDSCN TABLE: DB2IV91 ( 4) PRODUCT 37.8334 5 /-----+-----\ 1.03591 1.05842 SORT SORT ( 5) ( 7) 22.6972 15.1365 3 2 | | 1.03591 1.05842 IXSCAN IXSCAN ( 6) ( 8) 22.6967 15.136 3 2 | | 1.14541e+06 1.14541e+06 INDEX: DB2IV91 INDEX: DB2IV91 NXAKPRODUCT NXPRODUCT3 | |
Problem-Zusammenfassung: | |
**************************************************************** * USERS AFFECTED: * * db2 v95fp5 * **************************************************************** * PROBLEM DESCRIPTION: * * Certain queries running much slower after the implemented * * the new FEATURE ADDED TO BETTER SERVE MOST FETCH FIRST N * * ROWS (FFNR) in v95. * **************************************************************** * RECOMMENDATION: * * Upgrade to db2 v95fp8 * **************************************************************** | |
Local-Fix: | |
verfügbare FixPacks: | |
DB2 Version 9.5 Fix Pack 8 for Linux, UNIX, and Windows | |
Lösung | |
Regression will not be in db2 v95fp8 onwards | |
Workaround | |
keiner bekannt / siehe Local-Fix | |
Weitere Daten | |
Datum - Problem gemeldet : Datum - Problem geschlossen : Datum - der letzten Änderung: | 21.09.2010 20.07.2011 20.07.2011 |
Problem behoben ab folgender Versionen (IBM BugInfos) | |
9.5.FP8 | |
Problem behoben lt. FixList in der Version | |
9.5.0.8 |