id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
37179	Slicing a GDAL layer should scan layer once only	wongcht	wongcht	"In `django.contrib.gis.gdal.layer`'s `Layer.__getitem__`, if a layer (with **n** features) **does not support random read**, slicing the layer would call `_make_feature` at most **n** times which this method scan the whole layer until feature id matched.

E.g. Slicing a layer for 3 features (id= 1,2,3) would scan the layer 3 times: [1] for id=1, [1,2] for id=2, [1,2,3] for id=3. Worst case would call `__iter__` (`capi.get_next_feature`) for **n(n+1)/2** times

A better iteration should scan the layer once only to get all features required. A possible [https://github.com/wongcht/django/pull/2/changes fix] FYR"	Cleanup/optimization	assigned	GIS	dev	Normal		gdal		Unreviewed	0	0	0	0	1	0