Hi,

It is true, H2 doesn't use two indexes for the single query (the one
without union), as described in the documentation at
http://h2database.com/html/performance.html#storage_and_indexes

I just tested that Apache Derby doesn't use two indexes either (the same as H2).

I didn't test, but I guess other databases with a more advanced
optimizer (such as PostgreSQL) do use two indexes for this case. But
I'm not sure. I guess some databases can use two indexes, and some can
not.

Regards,
Thomas

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