Opened 10 years ago
Closed 10 years ago
#2895 closed enhancement (fixed)
Increase cost of ST_ConvexHull(raster)
| Reported by: | strk | Owned by: | strk |
|---|---|---|---|
| Priority: | medium | Milestone: | PostGIS 2.1.4 |
| Component: | raster | Version: | 2.1.x |
| Keywords: | history | Cc: |
Description
The cost of ST_ConvexHull(raster) is currently set to 1. For comparison ST_ConvexHull(geometry) is 100, and st_intersects(raster, raster) is 1000.
Real world cases have been found where a cost of 100 is not enough for the planner to choose a functional index scan for a query using a spatial condition on the raster column, while such index scan would take half the time (probably due to the pre-computation of the function output). See http://lists.osgeo.org/pipermail/postgis-devel/2014-August/024461.html
Raising it to 200 seems enough for the specific case.
It's to be determined out to deal with upgrades on function cost changes.
See #2839 for the change that made the problem more evident.
Change History (6)
comment:1 by , 10 years ago
comment:2 by , 10 years ago
| Component: | postgis → raster |
|---|---|
| Owner: | changed from to |
comment:3 by , 10 years ago
| Owner: | changed from to |
|---|---|
| Status: | new → assigned |
comment:4 by , 10 years ago
Raised to 300 in trunk with r12888. You are right upgrades are easy. Do you think I should backport to the 2.1 branch ?
comment:6 by , 10 years ago
| Keywords: | history added |
|---|---|
| Milestone: | PostGIS 2.2.0 → PostGIS 2.1.4 |
| Resolution: | → fixed |
| Status: | assigned → closed |
| Version: | trunk → 2.1.x |
r12892 for the 2.1 branch
I'm in agreement we need to up the cost on this. Didn't realize it was so low. I would go to 300 in fact as its more costly.
Hmm upgrades on function cost changes. Why do you need to do anything special with those? I would think putting in a CHANGED would be sufficient. Function costs are already part of the upgrade script.