Out of memory error

Hello,

I am running the following query:

SELECT
	indiv_fkey,
	MAX(emp_ind),
	MAX(prizm_cd_indiv),
	MAX(CASE
			WHEN div IS NULL THEN NULL
			WHEN store_loyal_loc_cd IS NULL THEN NULL
			ELSE div || '-' || store_loyal_loc_cd
		END)	,
	MAX(supp_all_adv_ind)	,
	MAX(supp_direct_mail_ind)
FROM
	cdm.cdm_fedcustomer
WHERE
	kept_acct_flg = 'Y' AND indiv_fkey IS NOT NULL
GROUP BY
	indiv_fkey;

AFTER A WHILE THE SYSTEM COMES BACK AND SAYS IN THE LOG FILE:

TopMemoryContext: 45592 total in 4 blocks; 4600 free (14 chunks); 40992 used
TopTransactionContext: 8192 total in 1 blocks; 8136 free (0 chunks); 56 used
DeferredTriggerXact: 0 total in 0 blocks; 0 free (0 chunks); 0 used
MessageContext: 57344 total in 3 blocks; 23312 free (1 chunks); 34032 used
PortalMemory: 8192 total in 1 blocks; 8040 free (0 chunks); 152 used
PortalHeapMemory: 1024 total in 1 blocks; 912 free (0 chunks); 112 used
ExecutorState: 24576 total in 2 blocks; 7416 free (3 chunks); 17160 used
ExprContext: 0 total in 0 blocks; 0 free (0 chunks); 0 used
AggContext: -1501569024 total in 351 blocks; 69904 free (507 chunks); 
-1501638928 used
DynaHashTable: 302047256 total in 46 blocks; 275720 free (66 chunks); 
301771536 used
ExprContext: 0 total in 0 blocks; 0 free (0 chunks); 0 used
ExprContext: 8192 total in 1 blocks; 8176 free (0 chunks); 16 used
CacheMemoryContext: 516096 total in 6 blocks; 114992 free (1 chunks); 401104 
used
indiv_key_idx: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
fed_cust_indiv_sum_pk: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
cdm_fedcustomer_idx4: 1024 total in 1 blocks; 320 free (0 chunks); 704 used
fedcust_lname_idx: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
fedcust_indivfkey_idx: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
pg_attrdef_adrelid_adnum_index: 1024 total in 1 blocks; 320 free (0 chunks); 
704 used
pg_database_oid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
pg_database_datname_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 
used
pg_index_indrelid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 
used
pg_amop_opc_strategy_index: 1024 total in 1 blocks; 320 free (0 chunks); 704 
used
pg_shadow_usename_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 
used
pg_amop_opr_opc_index: 1024 total in 1 blocks; 320 free (0 chunks); 704 used
pg_conversion_oid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 
used
pg_language_name_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 
used
pg_statistic_relid_att_index: 1024 total in 1 blocks; 320 free (0 chunks); 
704 used
pg_attribute_relid_attnam_index: 1024 total in 1 blocks; 320 free (0 
chunks); 704 used
pg_shadow_usesysid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 
used
pg_cast_source_target_index: 1024 total in 1 blocks; 320 free (0 chunks); 
704 used
pg_conversion_name_nsp_index: 1024 total in 1 blocks; 320 free (0 chunks); 
704 used
pg_trigger_tgrelid_tgname_index: 1024 total in 1 blocks; 320 free (0 
chunks); 704 used
pg_namespace_nspname_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 
used
pg_conversion_default_index: 2048 total in 1 blocks; 704 free (0 chunks); 
1344 used
pg_class_relname_nsp_index: 1024 total in 1 blocks; 320 free (0 chunks); 704 
used
pg_aggregate_fnoid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 
used
pg_inherits_relid_seqno_index: 1024 total in 1 blocks; 320 free (0 chunks); 
704 used
pg_language_oid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
pg_type_typname_nsp_index: 1024 total in 1 blocks; 320 free (0 chunks); 704 
used
pg_group_sysid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
pg_namespace_oid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 
used
pg_proc_proname_args_nsp_index: 2048 total in 1 blocks; 704 free (0 chunks); 
1344 used
pg_opclass_am_name_nsp_index: 2048 total in 1 blocks; 768 free (0 chunks); 
1280 used
pg_group_name_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
pg_proc_oid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
pg_operator_oid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
pg_amproc_opc_procnum_index: 1024 total in 1 blocks; 320 free (0 chunks); 
704 used
pg_index_indexrelid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 
used
pg_operator_oprname_l_r_n_index: 2048 total in 1 blocks; 704 free (0 
chunks); 1344 used
pg_opclass_oid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
pg_rewrite_rel_rulename_index: 1024 total in 1 blocks; 320 free (0 chunks); 
704 used
pg_type_oid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
pg_attribute_relid_attnum_index: 1024 total in 1 blocks; 320 free (0 
chunks); 704 used
pg_class_oid_index: 1024 total in 1 blocks; 640 free (0 chunks); 384 used
MdSmgr: 8192 total in 1 blocks; 6000 free (0 chunks); 2192 used
DynaHash: 8192 total in 1 blocks; 6560 free (0 chunks); 1632 used
DynaHashTable: 8192 total in 1 blocks; 2008 free (0 chunks); 6184 used
DynaHashTable: 8192 total in 1 blocks; 5080 free (0 chunks); 3112 used
DynaHashTable: 8192 total in 1 blocks; 2008 free (0 chunks); 6184 used
DynaHashTable: 8192 total in 1 blocks; 1984 free (0 chunks); 6208 used
DynaHashTable: 8192 total in 1 blocks; 3520 free (0 chunks); 4672 used
DynaHashTable: 24576 total in 2 blocks; 13240 free (4 chunks); 11336 used
DynaHashTable: 0 total in 0 blocks; 0 free (0 chunks); 0 used
DynaHashTable: 0 total in 0 blocks; 0 free (0 chunks); 0 used
DynaHashTable: 0 total in 0 blocks; 0 free (0 chunks); 0 used
DynaHashTable: 0 total in 0 blocks; 0 free (0 chunks); 0 used
DynaHashTable: 0 total in 0 blocks; 0 free (0 chunks); 0 used
ErrorContext: 8192 total in 1 blocks; 8176 free (0 chunks); 16 used
2006-06-23 09:27:52 [27143] ERROR:  out of memory
DETAIL:  Failed on request of size 420.
STATEMENT:  --INSERT INTO cdm_epiphany.fed_cust_indiv_summary_staging
        SELECT
                indiv_fkey,
                MAX(emp_ind),
                MAX(prizm_cd_indiv),
                MAX(CASE
                                WHEN div IS NULL THEN NULL
                                WHEN store_loyal_loc_cd IS NULL THEN NULL
                                ELSE div || '-' || store_loyal_loc_cd
                        END)    ,
                MAX(supp_all_adv_ind)   ,
                MAX(supp_direct_mail_ind)
        FROM
                cdm.cdm_fedcustomer
        WHERE
                kept_acct_flg = 'Y' AND indiv_fkey IS NOT NULL
        GROUP BY
                indiv_fkey;

===================================================================================================================
BUT WHEN I RAN THE FOLLOWING QUERY IT CAME BACK WITH THE COUNT. I DID AN 
EXPLAIN AND IT IS DOING A FULL TABLE SCAN WITH AN AGGREAGATE, BUT IN THE 
ABOVE QUERY IT IS DOING A FULL TABLE SCAN AND A HASH AGGREGATE TO GET TO THE 
RESULT.

SELECT
	count(*)
/*
	indiv_fkey,
	MAX(emp_ind),
	MAX(prizm_cd_indiv),
	MAX(CASE
			WHEN div IS NULL THEN NULL
			WHEN store_loyal_loc_cd IS NULL THEN NULL
			ELSE div || '-' || store_loyal_loc_cd
		END)	,
	MAX(supp_all_adv_ind)	,
	MAX(supp_direct_mail_ind)
*/
FROM
	cdm.cdm_fedcustomer
WHERE
	kept_acct_flg = 'Y' AND indiv_fkey IS NOT NULL
--GROUP BY
--	indiv_fkey;



I AM NEW TO POSTGRES AND I WOULD LIKE TO KNOW HOW TO FIX THIS ISSUE.

Thanks
Abu