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I have a table with over 18M rows that is growing quickly.

I created a composite index on a datetime column (millions of unique values), intColumn 1 (with about 40k unique values, intColumn 2 (with about 3k unique values) and intColumn 3 (with 1k unique values).

The cardinality of the index ended up being 197!

I am really confused by this and wonder if I did something wrong or is there something I am missing. This index seems useless.

Dan J
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ProBeachBum
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1 Answers1

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Try running ANALYZE TABLE and then check cardinality. Cardinality shown is just an estimate, and it is probably not correct.

Also, take a look here, it might be of some help.

Community
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Aleksandar Vucetic
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