Oleg Bartunov <obartunov(at)gmail(dot)com> writes:
> Hi there !
> I don't know when exactly it was improved, but following notice in
> https://www.postgresql.org/docs/current/static/textsearch-controls.html#TEXTSEARCH-HEADLINE
> is currently not needed.
> ts_headline uses the original document, not a tsvector summary, so it can
> be slow and should be used with care. A typical mistake is to call
> ts_headline for every matching document when only ten documents are to be
> shown. SQL subqueries can help; here is an example:
I don't see why that stopped being appropriate? The point is that it
takes a raw text input which has to be re-parsed; that's still true
AFAICS.
regards, tom lane