Hi, I have a table which contains generated static data (defined below) where the search_key field contains varying length strings. There are 122,000 rows in the table When the data is created the search_key field is ordered alphanumerically and assigned a unique order_key value starting at 1. The table is defined as: CREATE TABLE stuff ( code integer NOT NULL DEFAULT 0, search_key character varying(255), order_key integer, CONSTRAINT "PK_code" PRIMARY KEY (code) ) CREATE INDEX order_key ON stuff USING btree (order_key); ALTER TABLE stuff CLUSTER ON order_key; And a view defined as: CREATE OR REPLACE VIEW stuff_view AS select * from stuff Running the following query takes 56+ ms as it does a seq scan of the whole table: SELECT CODE FROM stuff WHERE SEARCH_KEY LIKE 'AAAAAA%' Running the following query takes 16+ ms as it does 2 index scans of the order_key index: SELECT CODE FROM stuff WHERE SEARCH_KEY LIKE 'AAAAAA%' and order_key >= ( SELECT order_key FROM stuff WHERE SEARCH_KEY LIKE 'AA%' order by order_key limit 1 ) and order_key < ( SELECT order_key FROM stuff WHERE SEARCH_KEY LIKE 'AB%' order by order_key limit 1 ) Running the following query takes less than a second doing a single index scan: SELECT CODE FROM stuff WHERE SEARCH_KEY LIKE 'AAAAAA%' and order_key >= 14417 and order_key < 15471 The problem query is always going to be in the first format. It was my intention to either change the view to intercept the query using a rule and either add the extra parameters from the second query OR Add a second table which contains the order_key ranges and add the extra parameters from the third query Is there an easier way to do this? As always, thanks for you help… Regards, Russell Keane INPS Tel: +44 (0)20 7501 7277 Follow us
on twitter | visit
www.inps.co.uk Registered name: In Practice Systems Ltd. Registered address: The Bread Factory, 1a Broughton Street, London, SW8 3QJ Registered Number: 1788577 Registered in England Visit our Internet Web site at www.inps.co.uk The information in this internet email is confidential and is intended solely for the addressee. Access, copying or re-use of information in it by anyone else is not authorised. Any views or opinions presented are solely those of the author and do not necessarily represent those of INPS or any of its affiliates. If you are not the intended recipient please contact is.helpdesk@xxxxxxxxxx |