Slow group query after add index

[irwan]

Im creating table like this

CREATE TABLE `tblinv` (
`tglorder` date NOT NULL,
`kdsls` varchar(7) NOT NULL,
`noorder` varchar(10) NOT NULL,
`tipe` varchar(1) NOT NULL,
`tglinv` date NOT NULL,
`noinv` varchar(10) default '',
`noinvrtr` varchar(10) default NULL,
`tglinvrtr` varchar(16) default NULL,
`jthtmp` date NOT NULL,
`paytipe` varchar(1) default '',
`kd_outlet` varchar(7) NOT NULL,
`norkp` varchar(10) default '',
`norkporder` varchar(10) default '',
`nopo` varchar(10) default NULL,
`prn` varchar(1) NOT NULL,
`btl` varchar(1) NOT NULL,
`ttlgross` double NOT NULL,
`disc1` double NOT NULL,
`disc2` double NOT NULL,
`disc3` double NOT NULL,
`promo` double NOT NULL,
`cashdisc` double NOT NULL default '0',
`ttlnett` double NOT NULL,
`ppn` double NOT NULL,
`ppnbm` double NOT NULL,
`ttlall` double NOT NULL,
`ttlallinp` double NOT NULL,
`diff` double NOT NULL,
`konsy` varchar(1) NOT NULL,
`byr` double NOT NULL,
`nopjk` varchar(20) default '',
`usr` varchar(10) NOT NULL,
`kdslskum` varchar(7) NOT NULL,
`kd_outletkum` varchar(7) NOT NULL,
`tgh` varchar(1) default '',
`kum` date NOT NULL,
`tglpjk` date default NULL,
`ttlpotpjk` double default '0',
`ttlrpmk` double default '0',
`ttldpp` double default '0',
`ttlppn` double default '0',
`ket` varchar(30) default NULL,
`tipepjk` varchar(2) default NULL,
`ketpjk` varchar(20) default NULL,
`expjk` varchar(10) default NULL,
`ttlgrosspjk` double default '0',
`tglbtl` date default NULL,
`tglreal` date default NULL,
`noreal` varchar(10) default NULL,
`tipebyr` varchar(1) default '0',
`TIPESLS` varchar(2) default NULL,
`flag` varchar(1) default '0',
`tglorderx` date NOT NULL,
`NOMIGO` varchar(100) NOT NULL default '',
`POD` varchar(1) NOT NULL,
`tagihan` date default NULL,
`gross_gl` double NOT NULL,
`ttlall_gl` double NOT NULL,
PRIMARY KEY (`tglorder`,`kdsls`,`noorder`,`tipe`),
KEY `Index_tblinv_kd_sls` USING BTREE (`kdsls`),
KEY `Index_tblinv_noorder` USING BTREE (`noorder`),
KEY `Index_tblinv_tipe` (`tipe`),
KEY `Index_tblinv_tglinv` USING BTREE (`tglinv`),
KEY `Index_tblinv_noinv` USING BTREE (`noinv`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 PACK_KEYS=0;

when i execute this command get 2 seconds :

select kd_outlet, sum(ttlall-byr) from tblinv where ttlall<>byr group by kd_outlet;

but when i add new index :

ALTER TABLE `tblinv` ADD INDEX `Index_tblinv_kd_outlet`(`kd_outlet`);

i got slowest query about 8 minutes... so i drop it again and get 2 second result
so why it's go to slowly.... my other report using "group by kd_outlet" got slowly with full scan table too

my tables contain 180.000-190.000 records

i'm trying import on Oracle 10Gi, it normal fast result with/out index

or should i change my query like this, i got fast result 18 sec with index :

select kd_outlet, sum(ttlall-byr) from
(
select kd_outlet, ttlall, byr from tblinv where ttlall<>byr
) as xxx
group by xxx.kd_outlet

or i see on manual, should i use sintax IGNORE INDEX... could any body give sample....

Rgrds