Subject: Re: [GENERAL] Why Postgres use a little memory on Windows.
To: tuanhoanganh <hatuan05@gmail.com>,
 PostgreSQL <pgsql-general@postgresql.org>,
 pgsql-performance <pgsql-performance@postgresql.org>
References: 
 <CAJg-yaO8OtzqTxsusesqntPhxG=LDc9skQe3SaVWw30NuWTs5Q@mail.gmail.com>
From: Adrian Klaver <adrian.klaver@aklaver.com>
Message-ID: <56C8ACBE.60004@aklaver.com>
Date: Sat, 20 Feb 2016 10:13:18 -0800
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On 02/20/2016 08:46 AM, tuanhoanganh wrote:
> 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;

Took liberty of reformatting the above here:
http://sqlformat.darold.net/

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;

The thing that stands out to me is that I do not see that sym_data and 
sym_data_gp are actually joined on anything.

Also is it possible to see the schema definitions for the two tables?


>
> 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
>
>
>


-- 
Adrian Klaver
adrian.klaver@aklaver.com


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