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High query cost estimate for Full Outer Join queries generated by MicroStrategy

Troubleshooting


Problem

MicroStrategy generated queries might have a very large estimated cost associated with the query.

Symptom

Queries generated by MicroStrategy that contain a series of Full Outer Join operations and expressions with COALESCE function could exhibit very high estimated cost. For example, QUERY_COST_ESTIMATE = 950138918693502976. This technote attempts to explain one of the reasons this may be so in DB2 LUW v9.7.

[{"Product":{"code":"SSEPGG","label":"Db2 for Linux, UNIX and Windows"},"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Component":"Compiler - Optimizer","Platform":[{"code":"PF002","label":"AIX"},{"code":"PF010","label":"HP-UX"},{"code":"PF016","label":"Linux"},{"code":"PF027","label":"Solaris"},{"code":"PF033","label":"Windows"}],"Version":"9.8;9.7","Edition":"","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

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Document Information

Modified date:
30 April 2025

UID

swg21626646