Re: Unique Index

Roman Neuhauser wrote:
> # alex@meerkatsoft.com / 2005-01-20 01:35:32 +1100:
>
>>i have a unique index on a table over multiple columns. If now one of
>>the records has a null value in one of the indexed columns i can insert
>>the same record multiple times.
>>
>>Is this a problem within postgres or expected?
>
>
>     In SQL, NULL means "unknown value". How could you assert that two
>     NULLs are equal?
>
which doesn't make mathematical sense.
mathwise null is an empty result.
so setting the logic up using the math logic, null values are always equal.

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