From: Adarsh Sharma <adarsh.sharma@orkash.com>
To: pgsql-performance@postgresql.org
Subject: Which is better Index
Date: Tue, 05 Apr 2011 15:56:52 +0530
Message-ID: <4D9AEE6C.50006@orkash.com> (raw)
Dear all,
I want to clear my doubts regarding creating several single or a
multi-column indexes.
My table schema is :-
CREATE TABLE svo2( svo_id bigint NOT NULL DEFAULT
nextval('svo_svo_id_seq'::regclass), doc_id integer, sentence_id
integer, clause_id integer, negation integer, subject
charactervarying(3000), verb character varying(3000), "object"
character varying(3000), preposition character varying(3000),
subject_type character varying(3000), object_type
charactervarying(3000), subject_attribute character varying(3000),
object_attribute character varying(3000), verb_attribute character
varying(3000), subject_concept character varying(100), object_concept
character varying(100), subject_sense character varying(100),
object_sense character varying(100), subject_chain character
varying(5000), object_chain character varying(5000), sub_type_id
integer, obj_type_id integer, CONSTRAINT pk_svo_id PRIMARY KEY
(svo_id))WITH ( OIDS=FALSE);
_*Fore.g*_
CREATE INDEX idx_svo2_id_dummy ON svo2 USING btree (doc_id, clause_id,
sentence_id);
or
CREATE INDEX idx_svo2_id_dummy ON svo2 USING btree (doc_id);
CREATE INDEX idx_svo2_id_dummy1 ON svo2 USING btree (clause_id);
CREATE INDEX idx_svo2_id_dummy2 ON svo2 USING btree (sentence_id);
Which is better if a query uses all three columns in join where clause.
Thanks & best regards,
Adarsh Sharma
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Cc: adarsh.sharma@orkash.com
Subject: Re: Which is better Index
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