Re: [GENERAL] Can't I create indexes on BOOL columns?

On 13 Dec 1999, Manuel Lemos wrote:

> Hello,
>
> I am using PostgreSQL 6.4.2.  and it seems I can't create indexes on
> BOOL columns.  I tried this:
>
> ...snip...
>
> However, if I change the BOOL type to CHAR (1) it works.

I'm not a developer, so I don't know if it's a bug or a logic error
you're pointing out, or even if it's an error at all.  However, I could
rationalize that it is not an error on the premise that BOOLEAN
identifiers can only have two values: true or false.

Obviously, you cannot use a UNIQUE index on such an column.  A Clustered
index would not do much better, logically, since you're only splitting
up the data into two groups.  Therefore, what is the point of indexing
on boolean columns, really?  I suppose it would depend upon the data in
the table.  If you see one value predominantly over the other, splitting
out the smaller group via the index *may* help your search.  However, if
the values are fairly even in proportion, you won't gain much.

I'd say stick with your work-around, and post the question to the devel
team.

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Chad Walstrom                         mailto:chewie@wookimus.net
a.k.a ^chewie, gunnarr               http://wookimus.net/~chewie

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