hi all, here's a query i've never been able to improve:
i have an old data set and a new data set - in this case uk postcodes with eastings and northings. i want to extract the new and changed postcodes from the new set. to get the changed entries i use a join and it works okay: SELECT n.postcode, n.easting, n.northing FROM v_postcode_new n, v_postcode_old o WHERE n.postcode = o.postcode AND (n.easting <> o.lattitude OR n.northing <> o.longitude); but then to get the entirely new items out i use a sub query which takes for ever SELECT DISTINCT * FROM v_postcode_new WHERE postcode NOT IN ( SELECT postcode FROM v_postcode_old ) ORDER BY postcode ASC; does anyone know of a quicker way to accomplish this? i guess there must be some cleaver way around it, but it's beyond me. thanks, jinn ---------------------------(end of broadcast)--------------------------- TIP 6: Have you searched our list archives? http://archives.postgresql.org
