Hi,
I found the bug !
It wasn't the ST_Dump, but was in the definition of MultiLineString ...
See-ing the WKT I notice the MultiLineStrings was all like this:
MULTILINESTRING(
(1678894.55 4826636.25,1678897.55 4826640.38),
(1678897.55 4826640.38,1678898.8 4826643.69),
(1678898.8 4826643.69,1678899.51 4826647.72),
(1678899.51 4826647.72,1678899.42 4826653.53),
(1678899.42 4826653.53,1678898.82 4826658.83),
(1678898.82 4826658.83,1678897.59 4826663.34),
(1678897.59 4826663.34,1678895.56 4826668.36)
)
So when I use the ST_Dump it produce this results:
LINESTRING(1678894.55 4826636.25,1678897.55 4826640.38)
LINESTRING(1678897.55 4826640.38,1678898.8 4826643.69)
LINESTRING(1678898.8 4826643.69,1678899.51 4826647.72)
LINESTRING(1678899.51 4826647.72,1678899.42 4826653.53)
LINESTRING(1678899.42 4826653.53,1678898.82 4826658.83
LINESTRING(1678898.82 4826658.83,1678897.59 4826663.34)
LINESTRING(1678897.59 4826663.34,1678895.56 4826668.36)
So I realized the bug was before...
Because I gave the MultiLineString from a command
ST_Multi(ST_Intersection(ST_Boundary(geom1),ST_Boundary(geom2)))
(where the geoms are polygons.)
See-ing the WKT of this result I notice all the results are MultiLines
Like this:
MULTILINESTRING(
(1678894.55 4826636.25,1678897.55 4826640.38),
(1678897.55 4826640.38,1678898.8 4826643.69),
(1678898.8 4826643.69,1678899.51 4826647.72),
(1678899.51 4826647.72,1678899.42 4826653.53),
(1678899.42 4826653.53,1678898.82 4826658.83),
(1678898.82 4826658.83,1678897.59 4826663.34),
(1678897.59 4826663.34,1678895.56 4826668.36)
)
But are always multilines of always segments with 2 only vertex !
So to resolve the problem I add an ST_LineMerge
ST_Multi(ST_LineMerge(ST_Intersection(ST_Boundary(a.geom),ST_Boundary(b.geom))))
Now the WKT is:
MULTILINESTRING(
(
1678894.55 4826636.25,
1678897.55 4826640.38,
1678898.8 4826643.69,
1678899.51 4826647.72,
1678899.42 4826653.53,
1678898.82 4826658.83,
1678897.59 4826663.34,
1678895.56 4826668.36
)
)
And doing the ST_Dump the result of the ST_Dump was:
LINESTRING(
1678894.55 4826636.25,
1678897.55 4826640.38,
1678898.8 4826643.69,
1678899.51 4826647.72,
1678899.42 4826653.53,
1678898.82 4826658.83,
1678897.59 4826663.34,
1678895.56 4826668.36
)
Thx for the suggestions ..
Andrea.
/ (ST_Dump(geom)).geom
/>>/ But unfortunately it give me again all segments with only 2 vertex :(
/>>/
/>>/ So from 1 MultiLineString with 2 parts each with 20+ vertex give me many
/>>/ LineStrings with only 2 vertex each :(
/
Could we have the example ?
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