Add condition makes sql so slow

don't know why
SELECT
SPM.PLU,
SPM.OWNERID,
SPM.PROMID,
S.DESCRIPTION,
SP.FAMILY,
SP.ORDERCODE,
SPM.SUPPLIERID,
PH.HOSTNUMBER,
PH.PROMCODE,
PH.PROMWEEK,
PH.PROMZONE
FROM PROMPRODHIST SPM
JOIN SUPPLIERPROD SP
ON( SP.OWNERID = 'G0000029' )
AND( SPM.OWNERID = SP.OWNERID )
AND( SPM.SUPPLIERID = SP.SUPPLIERID )
AND( SPM.PLU = SP.PLU )
JOIN PROMHEADER PH
ON( PH.OWNERID = SPM.OWNERID )
AND( PH.PROMID = SPM.PROMID )
JOIN STDPROD S
ON( SPM.PLU = S.PLU )


PLAN JOIN (SP INDEX (RDB$PRIMARY548),S INDEX (RDB$PRIMARY152),SPM INDEX (IDX_PROMPRODHIST_1),PH INDEX (RDB$PRIMARY554))


add the condition, the sql will be very slow ,
any idea here?

Thx
Roc

Have you tried:

WHERE ( SPM.OWNERID = 'G0000029' ) ?

Is SPM.OWNERID the primary key?

Yes, SPM.OWNERID is the previous one,
still very slow, so I changed like this, all the fields of
SPM used in the sql is primary key.

so strange, I only heard that adding conditions will make quicker, never see like this.

Can you post a script for us to reproduce the problem?

sorry for being offtopic, i'm too beginner to be able to help you, just wanted to ask what does that PLAN thing mean there?

and do you write that manually or some SQL editor did that?

Yes you are.
Why don't you open another thread asking what an explain plan is, how to have the database spit it out and, last but not least, how to read it?