Re: Deceiding which index to use

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Mezei Zoltán wrote:
Hi!

I have two tables with some indices on them:

CREATE TABLE subscriber
(
  id serial NOT NULL,
  anumber character varying(32) NOT NULL,
  CONSTRAINT subscriber_pk PRIMARY KEY (id)
)

CREATE INDEX anumber_idx_numeric
  ON subscriber
  USING btree
  (anumber::numeric);

I would like to run a query like this one:

select l.id
from output_message_log l join subscriber s on l.subscriber_id = s.id
where s.anumber::numeric = 5555555555
order by l.crd desc
limit 41
offset 20

Q1. Why are you storing a numeric in a varchar?
Q2. How many unique values does anumber have? And how many rows in subscriber? Q3. What happens if you create the index on plain (anumber) and then test against '555555555'?

--
  Richard Huxton
  Archonet Ltd


[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux