Re: Odd out of memory problem.

On 03/26/2012 12:20 PM, Greg Stark wrote:
> On Mon, Mar 26, 2012 at 4:03 PM, Andrew Dunstan<andrew@dunslane.net>  wrote:
>>               TupleHashTable: 619175960 total in 95 blocks; 821528 free
>>    (331 chunks); 618354432 used
> I think the plan you showed isn't the plan that's running out of
> memory. I think it's running out of memory because it's using a Hash
> Aggregate and underestimating the number of distinct elements. I would
> set enable_hash_aggregate=false for this query (not for the whole
> server, hash aggregates are quite useful in general).
>
> This is a long-standing problem with hash aggregates. The problem is
> that we don't have a clever way to fall back to a non-hash-aggregate
> if the original estimated memory usage turns out to be way off. Just
> spilling to disk the way hash joins do would be horrendously
> expensive, we think. If we had an approach to doing so it would be
> very useful because simply running out of memory is kind of rude.


Ugh, Ok, thanks for the explanation.

So it looks like I'm running into two separate memory problems. Here's a 
trace from the other one

cheers

andrew
   TopMemoryContext: 49816 total in 6 blocks; 6840 free (9 chunks);   42976 used      Operator class cache: 8192 total
in1 blocks; 3848 free (0   chunks); 4344 used      Filesystem: 8192 total in 1 blocks; 7872 free (0 chunks); 320 used
  TopTransactionContext: 213901336 total in 10 blocks; 1796344 free   (25 chunks); 212104992 used        Combo CIDs:
755490840total in 100 blocks; 5161072 free (381   chunks); 750329768 used      MessageContext: 73728 total in 4 blocks;
44920free (15 chunks);   28808 used      smgr relation table: 8192 total in 1 blocks; 2816 free (0   chunks); 5376 used
    TransactionAbortContext: 32768 total in 1 blocks; 32752 free (0   chunks); 16 used      Portal hash: 8192 total in
1blocks; 3912 free (0 chunks); 4280 used      PortalMemory: 8192 total in 1 blocks; 8040 free (0 chunks); 152 used
 PortalHeapMemory: 1024 total in 1 blocks; 920 free (0 chunks);   104 used          ExecutorState: 8192 total in 1
blocks;5880 free (1 chunks);   2312 used            ExprContext: 24576 total in 2 blocks; 13664 free (8   chunks);
10912used      Relcache by OID: 8192 total in 1 blocks; 3376 free (0 chunks);   4816 used      CacheMemoryContext:
405552total in 19 blocks; 14296 free (5   chunks); 391256 used        pg_largeobject_loid_pn_index: 1024 total in 1
blocks;240 free   (0 chunks); 784 used        pg_index_indrelid_index: 1024 total in 1 blocks; 304 free (0   chunks);
720used        pg_opclass_am_name_nsp_index: 1024 total in 1 blocks; 192 free   (0 chunks); 832 used
pg_foreign_data_wrapper_name_index:1024 total in 1 blocks; 344   free (0 chunks); 680 used        pg_enum_oid_index:
1024total in 1 blocks; 344 free (0 chunks);   680 used        pg_class_relname_nsp_index: 1024 total in 1 blocks; 280
free(0   chunks); 744 used        pg_foreign_server_oid_index: 1024 total in 1 blocks; 344 free   (0 chunks); 680 used
     pg_statistic_relid_att_index: 1024 total in 1 blocks; 280 free   (0 chunks); 744 used
pg_cast_source_target_index:1024 total in 1 blocks; 240 free   (0 chunks); 784 used        pg_language_name_index: 1024
totalin 1 blocks; 344 free (0   chunks); 680 used        pg_authid_oid_index: 1024 total in 1 blocks; 304 free (0
chunks);720 used        pg_amop_fam_strat_index: 1024 total in 1 blocks; 88 free (0   chunks); 936 used
pg_index_indexrelid_index:1024 total in 1 blocks; 304 free (0   chunks); 720 used        pg_ts_template_tmplname_index:
1024total in 1 blocks; 280 free   (0 chunks); 744 used        pg_ts_config_map_index: 1024 total in 1 blocks; 192 free
(0  chunks); 832 used        pg_opclass_oid_index: 1024 total in 1 blocks; 304 free (0   chunks); 720 used
pg_foreign_data_wrapper_oid_index:1024 total in 1 blocks; 344   free (0 chunks); 680 used
pg_auth_members_member_role_index:1024 total in 1 blocks; 280   free (0 chunks); 744 used        pg_ts_dict_oid_index:
1024total in 1 blocks; 344 free (0   chunks); 680 used        pg_conversion_default_index: 1024 total in 1 blocks; 128
free  (0 chunks); 896 used        pg_operator_oprname_l_r_n_index: 1024 total in 1 blocks; 128   free (0 chunks); 896
used       pg_trigger_tgrelid_tgname_index: 1024 total in 1 blocks; 240   free (0 chunks); 784 used
pg_enum_typid_label_index:1024 total in 1 blocks; 280 free (0   chunks); 744 used        pg_ts_config_oid_index: 1024
totalin 1 blocks; 344 free (0   chunks); 680 used        pg_user_mapping_oid_index: 1024 total in 1 blocks; 344 free (0
 chunks); 680 used        pg_opfamily_am_name_nsp_index: 1024 total in 1 blocks; 192 free   (0 chunks); 832 used
pg_type_oid_index:1024 total in 1 blocks; 304 free (0 chunks);   720 used        pg_aggregate_fnoid_index: 1024 total
in1 blocks; 344 free (0   chunks); 680 used        pg_constraint_oid_index: 1024 total in 1 blocks; 344 free (0
chunks);680 used        pg_rewrite_rel_rulename_index: 1024 total in 1 blocks; 280 free   (0 chunks); 744 used
pg_ts_parser_prsname_index:1024 total in 1 blocks; 280 free (0   chunks); 744 used        pg_ts_config_cfgname_index:
1024total in 1 blocks; 280 free (0   chunks); 744 used        pg_ts_parser_oid_index: 1024 total in 1 blocks; 344 free
(0  chunks); 680 used        pg_operator_oid_index: 1024 total in 1 blocks; 344 free (0   chunks); 680 used
pg_namespace_nspname_index:1024 total in 1 blocks; 304 free (0   chunks); 720 used        pg_ts_template_oid_index:
1024total in 1 blocks; 344 free (0   chunks); 680 used        pg_amop_opr_fam_index: 1024 total in 1 blocks; 280 free
(0  chunks); 744 used        pg_ts_dict_dictname_index: 1024 total in 1 blocks; 280 free (0   chunks); 744 used
pg_auth_members_role_member_index:1024 total in 1 blocks; 280   free (0 chunks); 744 used
pg_type_typname_nsp_index:1024 total in 1 blocks; 240 free (0   chunks); 784 used        pg_opfamily_oid_index: 1024
totalin 1 blocks; 344 free (0   chunks); 680 used        pg_class_oid_index: 1024 total in 1 blocks; 304 free (0
chunks);720 used        pg_proc_proname_args_nsp_index: 1024 total in 1 blocks; 152   free (0 chunks); 872 used
pg_attribute_relid_attnum_index:1024 total in 1 blocks; 240   free (0 chunks); 784 used        pg_proc_oid_index: 1024
totalin 1 blocks; 304 free (0 chunks);   720 used        pg_language_oid_index: 1024 total in 1 blocks; 344 free (0
chunks);680 used        pg_namespace_oid_index: 1024 total in 1 blocks; 344 free (0   chunks); 680 used
pg_database_oid_index:1024 total in 1 blocks; 304 free (0   chunks); 720 used        pg_amproc_fam_proc_index: 1024
totalin 1 blocks; 88 free (0   chunks); 936 used        pg_authid_rolname_index: 1024 total in 1 blocks; 304 free (0
chunks);720 used        pg_foreign_server_name_index: 1024 total in 1 blocks; 344 free   (0 chunks); 680 used
pg_attribute_relid_attnam_index:1024 total in 1 blocks; 280   free (0 chunks); 744 used        pg_conversion_oid_index:
1024total in 1 blocks; 344 free (0   chunks); 680 used        pg_user_mapping_user_server_index: 1024 total in 1
blocks;280   free (0 chunks); 744 used        pg_conversion_name_nsp_index: 1024 total in 1 blocks; 280 free   (0
chunks);744 used      MdSmgr: 8192 total in 1 blocks; 6160 free (0 chunks); 2032 used      LOCALLOCK hash: 8192 total
in1 blocks; 3912 free (0 chunks);   4280 used      Timezones: 79320 total in 2 blocks; 5968 free (0 chunks); 73352 used
    ErrorContext: 8192 total in 1 blocks; 8176 free (4 chunks); 16 used   2012-03-24 10:59:39 EDT ERROR:  out of memory
 2012-03-24 10:59:39 EDT DETAIL:  Failed on request of size 419430400.   2012-03-24 10:59:39 EDT STATEMENT:  SELECT
pg_catalog.lowrite(0,....