Обсуждение: BUG #18208: ts_headline MinWords and MaxWords cannot be set to the same value

The following bug has been logged on the website:

Bug reference:      18208
Logged by:          Oli
Email address:      oliverfwales@gmail.com
PostgreSQL version: 12.16
Operating system:   aarch64-unknown-linux-gnu
Description:

Setting MaxWords and MinWords to the same value (e.g. 30) in the options of
ts_headline throws the error "MinWords should be less than MaxWords". Is
there any reason why they must be different? Why not allow setting them to
the same value to allow a fixed number of words to be returned?

PG Bug reporting form <noreply@postgresql.org> writes:
> Setting MaxWords and MinWords to the same value (e.g. 30) in the options of
> ts_headline throws the error "MinWords should be less than MaxWords". Is
> there any reason why they must be different? Why not allow setting them to
> the same value to allow a fixed number of words to be returned?

[ shrug... ] I'd turn that around: why would that be a good idea?
Usually, you want quite a bit of room between MinWords and MaxWords
to allow a more-or-less-apropos text snippet to be returned.
It seems highly unlikely that the calling query knows enough about
the right snippet length (in advance of knowing the match) to get
good results by demanding an exact length.

            regards, tom lane