Re: Parallel Seq Scan - Mailing list pgsql-hackers

From Haribabu Kommi
Subject Re: Parallel Seq Scan
Date
Msg-id CAJrrPGeW0iJcju=x+DprWGu9k7Xb_pj-YqcX_ooio0qg7yKQvw@mail.gmail.com
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In response to Re: Parallel Seq Scan  (Amit Kapila <amit.kapila16@gmail.com>)
Responses Re: Parallel Seq Scan  (Amit Kapila <amit.kapila16@gmail.com>)
Re: Parallel Seq Scan  (Robert Haas <robertmhaas@gmail.com>)
List pgsql-hackers
On Thu, Sep 3, 2015 at 8:21 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
>
> Attached, find the rebased version of patch.

Here are the performance test results:

Query          selectivity    HashAgg                         HashAgg
                    (million)     + seqscan(ms)                +
parallel seq scan(ms)
                                                                    2
workers   4 workers      8 workers
$1 <= '001'      0.1           16717.00             7086.00
4459.00         2912.00
$1 <= '004'      0.4           17962.00             7410.00
4651.00         2977.00
$1 <= '008'      0.8           18870.00             7849.00
4868.00         3092.00
$1 <= '016'      1.5           21368.00             8645.00
6800.00         3486.00
$1 <= '030'      2.7           24622.00           14796.00    13108.00
        9981.00
$1 <= '060'      5.4           31690.00           29839.00    26544.00
      23814.00
$1 <= '080'      7.2           37147.00           40485.00    35763.00
      32679.00


Table Size - 18GB
Total rows - 40 million

Configuration:
Shared_buffers - 12GB
max_wal_size - 5GB
checkpoint_timeout - 15min
work_mem - 1GB

System:
CPU - 16 core
RAM - 64GB

Query:
SELECT col1, col2,
          SUM(col3)   AS sum_col3,
          SUM(col4)   AS sum_col4,
          SUM(col5)   AS sum_col5,
          SUM(col6)   AS sum_col6
     FROM public.test01
    WHERE col1 <= $1 AND
          col7      = '01'   AND
          col8 = '0'
 GROUP BY col2,col1;


And also attached perf results for selectivity of 0.1 million and 5.4
million cases for analysis.

Regards,
Hari Babu
Fujitsu Australia

Attachment

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