Hello Martijn Tonies,

>> So I wonder if this is the right approach. I tried to put indexes on
>> some fields like AUTHOR and TITLE, but I think the use of UPPER in the
>> ON-clause prevents using these indexes.

> That is correct, UPPER removes the ability to use an index. In
> Firebird 2, you could use expression based indices, in Firebird
> 1.5 or lower, I suggest you add a shadow field, eg: TITLE_UPPER,
> which you populate by using a before insert/update trigger and
> use that to do your compare... Considering the number of books
> with the same title, this should be quick quicker.

How about an index on a computed field ?



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