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<div align="left">Try St_Extent3D instead without st_collect. Then PostGIS can handle 1 point at a time and not all the 17 millions.</div>
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<div align="left">So try:</div>
<div align="left">SELECT ST_Extent3D(punkte) FROM rohdaten WHERE id=109;<br />
</div>
<div align="left"> </div>
<div align="left">ConvexHull is only working in 2D. It will keep the third dimension but not include it in the calculations (not 100% sure about that, but almost)</div>
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<div align="left">HTH</div>
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<div align="left">Nicklas<br />
<br />
2010-10-20 Jan Saalbach wrote:<br />
<br />
Hi all,<br />
>an "out of memory error" occurs when I issue the following command:<br />
><br />
>SELECT BOX3D(ST_COLLECT(punkte)) FROM rohdaten WHERE id=109;<br />
><br />
>"punkte" is a GeometryColumn filled with POINT3D, 17 million for id=109. <br />
>The machine has 4GB of ram.<br />
><br />
>I chose the box3d over the ConvexHull function because I thought it <br />
>would be much faster, and much less memory consuming. Apparently I was <br />
>wrong about memory consuming.<br />
><br />
>What I do not get is why a computation as simple as "min x,y,z and max <br />
>x,y,z all at once" should consume that much memory. Can someone explain <br />
>to me what point I am missing?<br />
><br />
>Issuing MIN(ST_X... MIN(ST_Y... commands one after another works fine <br />
>and is quite fast.<br />
><br />
>Regards,<br />
>Jan<br />
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><br />
> </div>
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