Detect Redundant Indexes

August 26, 2004

>>Script Language and Platform: T-Sql
This script gives a table, with Table, Index, Index contained, Index that contains.

I recommend to review each case, before you drop.

I run it in the Query Analyzer, one statement at a time.

Author: Fernando Madrigal Hidalgo

USE database

-- tab,idx,col,order
create view listaidxcols as 
select SO.name as tabname,
       SI.name as idxname,
       IK.keyno as keyno,
       SC.name as colname
from sysindexkeys IK, 
     syscolumns SC,
     sysindexes SI,
     sysobjects SO
where -- Link syscolumns
and   IK.colid=SC.colid
-- link sysindexes
and   IK.id=SI.id 
and   IK.indid=SI.indid
-- Link a sysObjects (tablas)
and   IK.id=SO.id
and   SO.xtype='U'
and   SI.name   not like '_WA_Sys_%'
and   SI.name   not like 'hind_%'

--  how many cols x index
create view cantcolsidx
as select tabname, 
          count(*) as numllaves
from listaidxcols
group by tabname,idxname

-- get the redundant index list
select A.tabname as tabla,A.idxname as Aidx, B.idxname as Bidx
from cantcolsidx A, cantcolsidx B
where A.tabname  = B.tabname
and A.numllaves < B.numllaves
and A.idxname   <> B.idxname
and A.numllaves in (
    select count(*)
    from listaidxcols C, listaidxcols D
    where C.tabname=A.tabname
    and   C.idxname=A.idxname
    and   D.tabname=B.tabname
    and   D.idxname=B.idxname
    and   C.idxname<>D.idxname
    and   C.colname=D.colname
    and   C.keyno  =D.keyno

-- Clean up
drop view listaidxcols;
drop view cantcolsidx;

Disclaimer: We hope that the information on these script pages is valuable to you. Your use of the information contained in these pages, however, is at your sole risk. All information on these pages is provided "as -is", without any warranty, whether express or implied, of its accuracy, completeness, or fitness for a particular purpose... Disclaimer Continued

Back to Database Journal Home