Question

How can I add a resultset (more than one entry) to a tsvector? I use postgres 8.3.
I have an m-n relationship and I’d like to have all values from one column of the n-side in the tsvector of the m-side.
This statement will work if I have an limit to one the subselect. But not without the limit.

UPDATE mytable
    SET mytsvector=to_tsvector('english', 
        coalesce(column_a, '') ||' '|| 
        coalesce((SELECT item FROM other_table WHERE id = other_id LIMIT 1), '')
    )



ERROR:  more than one row returned by a subquery used as an expression

Answer 1

Under Postgres 8.3 at first I have to create an aggregate function to generate an array from an select.

CREATE AGGREGATE array_accum ( 
   sfunc = array_append, 
   basetype = anyelement, 
   stype = anyarray, 
   initcond = '{}' 
);

Since 8.4 there is the function array_agg().

The hole statement looks like this:

UPDATE mytable
SET mytsvector=to_tsvector('english', 
    coalesce(column_a, '') ||' '|| 
    coalesce(
        (SELECT array_to_string(array_accum(item), ' ') 
         FROM mytable m, other_table o 
         WHERE o.id = m.other_id AND m.id = id GROUP BY m.id), '')
)