I believe the PostgreSQL optimizer is fooled by many ORs and switches
to sequential scans: it cannot estimate properly the quantity of
results that will be returned.
Try it in one go, as
$sql = "SELECT notam_id, TO_CHAR(full_issue_date, 'DD-MON-YYYY
HH24:MI') FROM notam_details WHERE item_a IN ('EGKB','EGDM','EGHH','EGGD','EGVN','EGFF',
'EGDC','EGTC','EGDR','EGTE','EGLF','EGTG', 'EGBJ','EGLC','EGKK','EGLL','EGSS','EGGW',
'EGMD','EGDL','EGUM','EGHD','EGHE','EGKA', 'EGHI','EGMC','EGDG','EGFH','EGDY','EGJA', 'EGJB','EGJJ')";
The optimizer should (I think) like this better and use the indices,
without requiring that you iterate the queries from the frontend.
As I am trying to learn these things too, I will appreciate knowing
about the result of your tests: please keep me posted.
Thanks
Miguel Sofer
