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Database is postgres 9.2, POSTGIS="2.0.2 r10789" GEOS="3.3.6-CAPI-1.7.6" PROJ="Rel. 4.7.1, 23 September 2009" LIBXML="2.7.8"

i have geometries in consecutive order. Here is query:

SELECT (ST_Union(geom)) FROM roads WHERE osm_id IN (140122771,140122775,9620011,9620010,174011196,9620025,174011193,174011195,9620024,140119144,4377642,183432458,193166932,140119146,183432465,140119145,183811230,25585759,25585692,183811266,25585671)

osm_id is in order that i need them. after i run second query:

SELECT (
    ST_Line_Interpolate_Point(
        ST_LineMerge(
            ST_Line_Substring(
                (SELECT (ST_UNION(geom)) FROM roads WHERE osm_id IN (140122771,140122775,9620011,9620010,174011196,9620025,174011193,174011195,9620024,140119144,4377642,183432458,193166932,140119146,183432465,140119145,183811230,25585759,25585692,183811266,25585671)  ),
                 0.1, 0.101
            )
         ),0.1
    )
) as punkts 

it produces point on line. ( i rand 9 queries from 0.1 to 0.9. 0.1 is first, 0.2 is second and so on), but points not in consecutive order.
points on line , must be from bottom to top

You can see, that 4 point is at end of line .. Is there way, that i can union geometries in consecutive order? or maybe geometries can concatenate ?

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