QGIS take ages to open big shapefiles

[lutra]

Hi,

I noticed that while trying open a quite big shapefile

​http://www.iucnredlist.org/resources/spatial/mammals/cetartiodactyla_v1223400057.zip

Qgis freezes, or at least do not give sign of life for a long time. The same shapefile on other software (ex. gvsig) opens in a matter of seconds.

Using QGIS trunk (compiled today) under Ubuntu 9.04

The same behaviour was reported by others with other big shapefiles.

[lutra]

The link to that shapefile is no more available, use this instead

​http://www.iucnredlist.org/spatial-data/MAMMALS_TERRESTRIAL.zip

Actually the behaviour changed as QGis seems not to freeze anymore, it just take ages to open the shapefile and take even more to do any kind of basic (pan, zoom, etc.) operation. Using render caching do not seems to have any positive effect.

Also configuring QGis to draw "x" features before updating the display (options -> rendering & svg) does not work for me.

Tested on both linux and windows xp with QGis trunk.

[lutra]

well, after all the render caching seems to have some kind of positive effect, but the time needed to go around in such a shapefile is still way too high (it takes just one minute instead of two).

I noticed also that is tremendously slow while opening the table of attributes.

[lutra]

Also configuring QGis to draw "x" features before updating the display (options -> rendering & svg) does not work for me.

as confirmed in #2038, does not work if cache rendering is enabled.

[lutra]

Well,

after a mail exchange with one of the main developers it results that this is not a QGIS issue but a QT issue, and so little can be done for now.

We can leave this open as reminder or close it. Opinions?

[lutra]

It seems that with the fix for #2270 there was an improvement in the rendering performances of the big shapefile linked in this ticket (650mb of size). Still slow but now it is at least usable.

I still see serious speed issues using (for example) the identify/select feature tools, but zooming seems improved.

I especially noticed that if the identify tool results window is docked, then just selecting the identify tool make the canvas to be refreshed, hurting the user experience.

[pcav]

The problem is still there. In real work with complex data this is really a stumbling block. I checked, and on the same machine, ArcMap opens the same file much faster.