[postgis-users] optimazing intersection

[Markus Schaber]

Hi, Toni,

First, please don't reply to an existing message when creating a new
topic. Your mail program still generates the In-Reply-To: header, and
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toni hernández wrote:

> I have to intersect lots of Multilinestrings so the process is very time
> consuming.
> I thought that maybe with a tranlation (translate(geom, -400000,-600000)
> of the geometries (to get smaller numbers) it would increase speed but
> the truth is that the difference is not relevant.

I'd expect that, as translating the geometry does not changei its
complexity (number of vertices etc.)

> Do you have any other suggestions to increase the intersection efficiency?

You did not tell us what exactly you want to do.

Do you have to intersect them pair-wise, or all together (to get the
common piece for all of them)?

In the latter case, you could sort them by number of vertices, and begin
with the smallest ones.

In the former case, maybe a bbox-overlap check could sort out those
pairs that don't even come close.

If you need more specific help, please give us more details.

HTH,
Markus