GEQO and KSQO problem.

Hello all!

When i had posted the SQL query like this

"select distinct CLIENTS.CLIENTID,PRINADLEG.PRIM,CLIENTS.NAME_1,CLIENTS.NAME_2,CLIENTS.STRANA,CLIENTS.REGION,
CLIENTS.INDEKC,
CLIENTS.GOROD,CLIENTS.OBLAST,CLIENTS.ULICA_DOM,CLIENTS.A_YA,CLIENTS.FLG_ADR,CLIENTS.TYP_CLS,
CLIENTS.SITE,CLIENTS.OTRASL,
CLIENTS.VID_D,CLIENTS.KATEGOR,CLIENTS.METKI,CLIENTS.MANAGER,CLIENTS.MANAGER_ID, CLIENTS.PRIM,CLIENTS.ARH,CLIENTS.NEW_F,
CLIENTS.WRITER,CLIENTS.FLG_MY
from CLIENTS ,PRINADLEG ,SOTRUD
where CLIENTS.CLIENTID=SOTRUD.CLIENTID and
( CLIENTS.PRINADL=PRINADLEG.PRINADL and CLIENTS.FLG_MY and (NOT CLIENTS.ARH) and lower(SOTRUD.EMAIL) LIKE
lower('%ruslanmr@hotmail.com%')
  OR CLIENTS.PRINADL=PRINADLEG.PRINADL and CLIENTS.FLG_MY and (not CLIENTS.ARH) and lower(SOTRUD.EMAIL) LIKE
lower('%matukin@hotmail.com%') 
  OR CLIENTS.PRINADL=PRINADLEG.PRINADL and CLIENTS.FLG_MY and (not CLIENTS.ARH) and lower(SOTRUD.EMAIL) LIKE
lower('%knirti@kaluga.ru%') 
  OR CLIENTS.PRINADL=PRINADLEG.PRINADL and CLIENTS.FLG_MY and (not CLIENTS.ARH) and lower(SOTRUD.EMAIL) LIKE
lower('%avk@vniicom.vsu.ru%')
  OR CLIENTS.PRINADL=PRINADLEG.PRINADL and CLIENTS.FLG_MY and (not CLIENTS.ARH) and lower(SOTRUD.EMAIL) LIKE
lower('%avk@vniicom.vsu.ru%')
)
order by CLIENTS.NEW_F, CLIENTS.NAME_1"

my server worked very, very slow. When i  had tried shutdown it's borrowed 1 hour aproximately.

In postgres log file i saw message:
FATAL 1: palloc memory memory exhausted

I have found in the postgres mailing lists that it was a GEQO problem.
I tried to turn on the KSQO, but there was no any effect.
In documentaion there is a phrase like this
    "Memory exhaustion may occur with more than 10 relation involved in a query."
But i have only 3 relation involved in query.

What is a solution of the this problem?

Thanks for help

                Natalya Makushina
                mak@rtsoft.msk.ru