[postgis-users] how to efficiently query multipoint

[Biddy]

Hi everyone,

I am not very experienced with PostGIS and so I wonder if anybody here  
might be able to give me a pointer on how to do the following  
efficiently:

I have a table with a multipoint geometry.
I have approx. 500 points per multipoint.
I would like to query the table, looking for points within the dataset  
that are within a certain distance from a specified point. And  
possibly return the result as a linestring (just points is ok too).

Any help is greatly appreciated!

Cheers,
B.