Re: a spatial table's bounding box

2011/9/22 Asli Akarsakarya <asliakar(at)yahoo(dot)com>

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> I want to get the extensions of spatial table. Say that there is a spatial table named 'roads', and a some road geometry inside. I want to fetch the bounding box (envelope or extension) for that table, that means for all the roads that it has.
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> According the OGC specification, this should be defined in the "geometry_columns" table. As four columns, "minX", "minY", "maxX" and "maxY". But I couldn't find it anywhere on my postgis. Yet.
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> From which table/view? With what SQL?
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I would try

SELECT st_envelope( st_collect(geom) ) FROM roads;

HTH, Filip