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 in 1 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: 755490840 total in 100 blocks; 5161072 free (381
    chunks); 750329768 used
       MessageContext: 73728 total in 4 blocks; 44920 free (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 1 blocks; 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); 10912 used
       Relcache by OID: 8192 total in 1 blocks; 3376 free (0 chunks);
    4816 used
       CacheMemoryContext: 405552 total 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); 720 used
         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: 1024 total 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 total in 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: 1024 total 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: 1024 total 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 total in 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 in 1 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: 1024 total 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: 1024 total 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 total in 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 total in 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 total in 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: 1024 total 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 in 1 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, ....