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    <p>I know this is not the answer you want, but the difference is really negligeble in all but the most extreme special cases. And in each such specific case, simply switching datatype won't be enough to fix a performance problem. </p> <p>For example, here are some alternatives that will outperform any datatype changes by a large factor. Each carries with it a downside of course.</p> <p>If you have 200 optional flags and you query for at most 1-2 at a time for lots of rows, you would get better performance by having each flag in its own table. If the data is really sparse this gets even better. </p> <p>If you have 200 mandatory flags and you only perform single record fetches, you should put them in the same table.</p> <p>If you have a small set of flags, you could pack them in one column using a bitmask, which is efficient storage wise, but you won't be able to (easily) query individual flags. Of course, this doesn't work when flags can be NULL...</p> <p>Or you could get creative and use a "junk dimension" concept, in which you create a separate table with all 200 boolean flags represented as columns. Create one row for each distinct combination of flag values. Each row gets an autoincrement primary key, which you reference in the master record. Voila, the master table now contains 1 int, instead of 200 columns. Hackers heaven, DBA nightmare.</p> <p>The point I'm trying to make is that even though it is interesting to argue over which is "the best", there are other concerns that are of much greater importance (like the comment you quoted). Simply because when you encounter a real performance issue, the datatype will neither be the problem nor the solution. </p>
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    1. POWhat's the optimal way to store binary flags / boolean values in each database engine?
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    1. USRonnis
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      1. VTUpMod
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