ERROR: out of memory - Mailing list pgsql-general

Hi.

I got an error when I try to VACUUM ANALYZE table.

# VACUUM ANALYZE n_traf;
ERROR:  out of memory
DETAIL:  Failed on request of size 536870910.

In logfile:
TopMemoryContext: 33464512 total in 12 blocks; 10560 free (61 chunks);
33453952 used
TopTransactionContext: 8192 total in 1 blocks; 7688 free (2 chunks); 504 used
SPI Plan: 3072 total in 2 blocks; 976 free (0 chunks); 2096 used
SPI Plan: 3072 total in 2 blocks; 648 free (0 chunks); 2424 used
RI query cache: 24576 total in 2 blocks; 14136 free (5 chunks); 10440 used
Local Buffer Lookup Table: 253952 total in 5 blocks; 120536 free (16
chunks); 133416 used
Type information cache: 8192 total in 1 blocks; 1800 free (0 chunks); 6392 used
Operator class cache: 8192 total in 1 blocks; 4872 free (0 chunks); 3320 used
MessageContext: 8192 total in 1 blocks; 7312 free (2 chunks); 880 used
smgr relation table: 8192 total in 1 blocks; 1776 free (0 chunks); 6416 used
TransactionAbortContext: 32768 total in 1 blocks; 32752 free (0 chunks); 16 used
Portal hash: 8192 total in 1 blocks; 3912 free (0 chunks); 4280 used
PortalMemory: 8192 total in 1 blocks; 8040 free (0 chunks); 152 used
PortalHeapMemory: 3072 total in 2 blocks; 3000 free (5 chunks); 72 used
Vacuum: 8192 total in 1 blocks; 8136 free (0 chunks); 56 used
Relcache by OID: 8192 total in 1 blocks; 3376 free (0 chunks); 4816 used
CacheMemoryContext: 659000 total in 19 blocks; 219336 free (2 chunks);
439664 used
nn_cpnt_date_time_account_id: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
nn_cpnt_account_id_date_time: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
nn_cpnt_pkey: 1024 total in 1 blocks; 392 free (0 chunks); 632 used
pg_description_o_c_o_index: 1024 total in 1 blocks; 216 free (0
chunks); 808 used
n_traftypes_pkey: 1024 total in 1 blocks; 392 free (0 chunks); 632 used
n_logins_login_pwd: 1024 total in 1 blocks; 328 free (0 chunks); 696 used
n_logins_login_id: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
n_logins_account_id: 1024 total in 1 blocks; 392 free (0 chunks); 632 used
n_logins_pkey: 1024 total in 1 blocks; 392 free (0 chunks); 632 used
n_logins_login_key: 1024 total in 1 blocks; 392 free (0 chunks); 632 used
pg_shdepend_depender_index: 1024 total in 1 blocks; 216 free (0
chunks); 808 used
pg_shdepend_reference_index: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
pg_depend_depender_index: 1024 total in 1 blocks; 216 free (0 chunks); 808 used
pg_depend_reference_index: 1024 total in 1 blocks; 216 free (0 chunks); 808 used
pg_toast_2619_index: 1024 total in 1 blocks; 288 free (0 chunks); 736 used
n_traf_login_id_date_time_traftype_id: 1024 total in 1 blocks; 216
free (0 chunks); 808 used
n_traf_date_time_login_id: 1024 total in 1 blocks; 288 free (0 chunks); 736 used
pg_index_indrelid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_attrdef_adrelid_adnum_index: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
pg_type_typname_nsp_index: 1024 total in 1 blocks; 288 free (0 chunks); 736 used
pg_type_oid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_trigger_tgrelid_tgname_index: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
pg_statistic_relid_att_index: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
pg_auth_members_member_role_index: 1024 total in 1 blocks; 328 free (0
chunks); 696 used
pg_auth_members_role_member_index: 1024 total in 1 blocks; 328 free (0
chunks); 696 used
pg_rewrite_rel_rulename_index: 1024 total in 1 blocks; 328 free (0
chunks); 696 used
pg_proc_proname_args_nsp_index: 1024 total in 1 blocks; 216 free (0
chunks); 808 used
pg_proc_oid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_operator_oprname_l_r_n_index: 1024 total in 1 blocks; 152 free (0
chunks); 872 used
pg_operator_oid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_opclass_oid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_opclass_am_name_nsp_index: 1024 total in 1 blocks; 216 free (0
chunks); 808 used
pg_namespace_oid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_namespace_nspname_index: 1024 total in 1 blocks; 352 free (0
chunks); 672 used
pg_language_oid_index: 1024 total in 1 blocks; 392 free (0 chunks); 632 used
pg_language_name_index: 1024 total in 1 blocks; 392 free (0 chunks); 632 used
pg_inherits_relid_seqno_index: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
pg_index_indexrelid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_authid_oid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_authid_rolname_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_database_oid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_conversion_oid_index: 1024 total in 1 blocks; 392 free (0 chunks); 632 used
pg_conversion_name_nsp_index: 1024 total in 1 blocks; 328 free (0
chunks); 696 used
pg_conversion_default_index: 1024 total in 1 blocks; 192 free (0
chunks); 832 used
pg_class_relname_nsp_index: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
pg_class_oid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
pg_cast_source_target_index: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
pg_attribute_relid_attnum_index: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
pg_attribute_relid_attnam_index: 1024 total in 1 blocks; 288 free (0
chunks); 736 used
pg_amproc_opc_proc_index: 1024 total in 1 blocks; 216 free (0 chunks); 808 used
pg_amop_opr_opc_index: 1024 total in 1 blocks; 288 free (0 chunks); 736 used
pg_amop_opc_strat_index: 1024 total in 1 blocks; 216 free (0 chunks); 808 used
pg_aggregate_fnoid_index: 1024 total in 1 blocks; 352 free (0 chunks); 672 used
MdSmgr: 8192 total in 1 blocks; 7528 free (0 chunks); 664 used
LOCALLOCK hash: 8192 total in 1 blocks; 3912 free (0 chunks); 4280 used
Timezones: 48616 total in 2 blocks; 5968 free (0 chunks); 42648 used
ErrorContext: 8192 total in 1 blocks; 8176 free (0 chunks); 16 used

It occures when I set "shared_buffers = 768M" ("maintenance_work_mem = 512MB").

Related sysctl settings are:
kern.seminfo.semmni=4096
kern.seminfo.semmns=4096
kern.seminfo.semmnu=256

kern.shminfo.shmall=1073741824
kern.shminfo.shmmax=838860800
kern.shminfo.shmmni=8192
kern.shminfo.shmseg=1024

My machine has 2G RAM. And I want make postgres utilize it...
--
engineer