Hello,

Apart from unicity, PK "not enforced" usage is disapointing regarding statistic lacks and I wonder what db2 optimizer can do with it really.
I would have expected a "virtual index" being inserted in SYSCAT.INDEXES, therefore a PK on (col1, col2, col3) would have firstkeycard, first2keycards, etc ... available to the optimizer.
But this is not implemented this way and we have to create a statistics profile with colgroups ourself.

This is really annoying for card estimation.

Best regards, JMB

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Jean-Marc BLAISE
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#Db2

Hi JMB,

i think it is usefull to be able to add a foreign key (RI) pointing to the table.

without RI between Fact Tables and Dimension Tables, DB2 is a mess. query generate hash_join_overflows and uses all tempspace.

Best regards,

Malek SHABOU

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malek shabou
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