Hi,
On Dec 26, 2007 9:23 PM, 232160563 <[EMAIL PROTECTED]> wrote:
> i can not understand sentences as following:
>
> For a BTREE index, an interval might be usable for conditions combined with
> AND, where each condition compares a key part with a constant value using =,
> <=>, IS NULL, >, <, >=, <=, !=,<>, BETWEEN, or LIKE 'pattern' (where
> 'pattern' does not start with a wildcard). An interval can be used as long as
> it is possible to determine a single key tuple containing all records that
> match the condition (or two intervals if <> or != is used).
>
> especially the second sentence :
>
> An interval can be used as long as it is possible to determine a single key
> tuple containing all records that match the condition (or two intervals if <>
> or != is used).
> (7.2.5.2. Range Access Method for Multiple-Part Indexes in the manual of
> mysql)
>
> the example showed in the manual is :
>
> key_part1 = 'foo' AND key_part2 >= 10 AND key_part3 > 10
>
> The single interval is:('foo', 10, 10)< (key_part1, key_part2, key_part3)<
> ('foo', +inf, +inf)
>
> It is possible that the created interval contains more records than the
> initial condition. For example,the preceding interval includes the value
> ('foo', 11, 0), which does not satisfy the original condition.
You should file a bug report against the documentation, then.
Cheers
Baron
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