Big array speed issues

Hi,

I have some speed issues with a big array in a table. I hope you can help me to tune my query.

My table looks like this:

Id                |  timestamp  | map
Primary key |  timestamp  | array of real [34][28]

With an index on timestamp

My query is the following:

Select map[1,1], map[1,2] …. Map[34,28] from table where timestamp > x and timestamp < y order by timestamp

Expected return is about 5000 rows of the table. I have to run this query multiple times with different x and y values

The table is huge (about 60000 entries) but will get even much more bigger.

The query takes ages on a 3.GhZ Xeon processor with 2 GB RAM.  I'm using postgresql 7.4 .

Any hints how I can speedup this ?  (use postgres 8.1, change table setup, query one row or column of the array )

I use libpqxx to access the database. This might be another bottleneck, but I assume my query and table setup is the bigger bottleneck. Would it make sense to fetch the whole array ? (Select map from table where …  and parse the array manually)

Thanks for your help.

Marcel