Re: Highly Variable Planning Times

On Wed, Apr 19, 2017 at 2:39 PM, Michael Malis <michaelmalis2(at)gmail(dot)com>
wrote:

> > TBH, I see no convincing explanation in that article of why 1300 partial
> > indexes are a good idea.
>
> I don't like it much either. I've been trying to eliminate most of the
> need for the partial indexes, but this is the current state of things.
>
> > *At best*, you're doing substantial work in the
> > planner to avoid the first tree descent step or two in a single
> > non-partial index.
>
> While the specific example I gave in the post could be replaced with a
> non-partial index, most of the partial indexes contain predicates that
> are not straightforward to index with non-partial indexes. About 85%
> of the partial indexes contain a regular expression in them for CSS
> selector matching. I've tried using a trigram GIN index, but it wound
> up not working too well due to the data being highly redundant (almost
> every CSS hierarchy contains 'div' in it).

pg_trgm 1.2 or higher has code to help with very common trigrams. But to
try it, you would need to upgrade PostgreSQL to 9.6.

Cheers,

Jeff