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by chasil 21 days ago
When you need many booleans on a table, use an integer with bitwise and/or to record them as powers of 2.

I have done this many times. Function-based indexes are necessary if they must be searched.
1 comments
echoangle 20 days ago
Why would you do that? To save some bytes in storage?
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chasil 20 days ago
The largest table where I've done this had over 50 of these booleans.

That's one 64-bit number, or 50 different columns.

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echoangle 20 days ago
But if you do the function based index, you actually increase the stored size, right? Seems like a microoptimization to me that I would only do if I really have to.
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chasil 20 days ago
For the searched column only?

If you are greatly concerned, SQL Server and the Sybase database from which it emerged have a native boolean data type.

Another benefit of this scheme is that adding another boolean means using the next power of 2 in the existing integer, assuming room remains. No new column necessary.

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