out of memory

Whenever I run this query, I get out of memory error:


explain analyze
select
email_track.count AS "Emails_Access_Count",
activity.subject AS "Emails_Subject",
crmentity.crmid AS EntityId_crmentitycrmid
from
(select * from crmentity where deleted = 0 and createdtime between (now() - interval '6 month') and now() ) as crmentity
inner join
(select * from activity where  activitytype = 'Emails' and date_start between (now() - interval '6 month')  and now()) as activity
on crmentity.crmid=activity.activityid
inner join emaildetails on emaildetails.emailid = crmentity.crmid
inner join vantage_email_track on vantage_email_track.mailid=emaildetails.emailid
left join seactivityrel on seactivityrel.activityid = emaildetails.emailid