[PERFORM] Why Postgres use a little memory on Windows.

[tuanhoanganh <hatuan05@xxxxxxxxx>]

Hello

I have a bad query on PostgreSQL 9.0.23 - 64bit - Windows 2012 R2 - 48GB Ram

explain analyze select d.data_id, d.table_name, d.event_type, d.row_data, d.pk_data, d.old_data, d.create_time, d.trigger_hist_id, d.channel_id, d.transaction_id, d.source_node_id, d.external_data, '' from sym_data d inner join sym_data_gap g on g.status='GP' and d.data_id between g.start_id and g.end_id where d.channel_id='sale_transaction' order by d.data_id asc;

Here is result

Nested Loop  (cost=319.42..4879348246.58 rows=32820035265 width=1525) (actual time=64656.747..5594654.189 rows=3617090 loops=1)
  ->  Index Scan using sym_data_pkey on sym_data d  (cost=0.00..3671742.82 rows=3867095 width=1525) (actual time=9.775..12465.153 rows=3866359 loops=1)
        Filter: ((channel_id)::text = 'sale_transaction'::text)
  ->  Bitmap Heap Scan on sym_data_gap g  (cost=319.42..1133.51 rows=8487 width=8) (actual time=1.438..1.439 rows=1 loops=3866359)
        Recheck Cond: ((d.data_id >= g.start_id) AND (d.data_id <= g.end_id))
        Filter: (g.status = 'GP'::bpchar)
        ->  Bitmap Index Scan on sym_data_gap_pkey  (cost=0.00..317.30 rows=8487 width=0) (actual time=1.436..1.436 rows=1 loops=3866359)
              Index Cond: ((d.data_id >= g.start_id) AND (d.data_id <= g.end_id))

http://explain.depesz.com/s/c3DT

I have run vaccum full. Here is my PostgreSQL config

shared_buffers = 2GB
work_mem = 64MB
maintenance_work_mem = 1GB
wal_buffers = 256
effective_cache_size = 4GB
checkpoint_segments = 256
wal_level = hot_standby
max_wal_senders = 5
wal_keep_segments = 256
random_page_cost = 3.5
autovacuum_vacuum_threshold = 1000
autovacuum_analyze_threshold = 250
max_locks_per_transaction = 2000

When I check taskmanager, I found postgres process is user 4-5MB

What happened with my PostgreSQL. Please help me

Thank you in advance.

Tuan Hoang Anh