Thanks Tom,David and Chris for detailed opinions Regards, Arun
On Sat, 23 Mar 2024 at 09:25, arun chirappurath <arunsnm...@gmail.com> wrote: > Hi All, > > I have a table named users with index on user name. > > CREATE TABLE users ( > user_id SERIAL PRIMARY KEY, > username VARCHAR(50) NOT NULL, > email VARCHAR(100) UNIQUE NOT NULL, > age INT > ); > > CREATE INDEX idx_username ON users (username); > > When I try to do below select query it's taking seq scan and query returns > in 5ms. > > SELECT * FROM users WHERE username = 'example_username'; > > I am trying to force query to use indexes using query hints. > > Set enable indexscan to ON, > Same for bitmap and index only scan > > and ran the query. > > However it still uses seq scan instead of index scan. > > 1. Is there a way to force query to use an index? With out changing > default settings of postgres rds > > 2. Modifying random page cost is desired the way or hint extension? In > which case do we use this?will it affect selecting index for all queries > > 3.i have done analyze on the table and tried recreating index..why is it > still taking seq scan? > > In Sql server we can force query just by proving it directly in query. > > USE AdventureWorks > GO > SELECT c.ContactID > FROM Person.Contact c > WITH (INDEX(AK_Contact_rowguid)) > INNER JOIN Person.Contact pc > WITH (INDEX(PK_Contact_ContactID)) > ON c.ContactID = pc.ContactID > GO > > > https://blog.sqlauthority.com/2009/02/07/sql-server-introduction-to-force-index-query-hints-index-hint/ > > Thanks, > Arun >
