From: | Rahila Syed <rahila(dot)syed(at)2ndquadrant(dot)com> |
---|---|
To: | pgsql-hackers(at)lists(dot)postgresql(dot)org, kommi(dot)haribabu(at)gmail(dot)com |
Subject: | Re: Transaction commits VS Transaction commits (with parallel) VS query mean time |
Date: | 2019-03-19 03:32:48 |
Message-ID: | CAOajBXSqw8Pjk=N2iwd0+nWkZkdPE7JJdJ3ZSYXeOurc-fgQkg@mail.gmail.com |
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Lists: | pgsql-hackers |
Hi Haribabu,
The latest patch fails while applying header files part. Kindly rebase.
The patch looks good to me. However, I wonder what are the other scenarios
where xact_commit is incremented because even if I commit a single
transaction with your patch applied the increment in xact_commit is > 1. As
you mentioned upthread, need to check what internal operation resulted in
the increase. But the increase in xact_commit is surely lesser with the
patch.
postgres=# BEGIN;
BEGIN
postgres=# select xact_commit from pg_stat_database where datname =
'postgres';
xact_commit
-------------
158
(1 row)
postgres=# explain analyze select * from foo where i = 1000;
QUERY
PLAN
------------------------------------------------------------------------------------------------------------------------
Gather (cost=1000.00..136417.85 rows=1 width=37) (actual
time=4.596..3792.710 rows=1 loops=1)
Workers Planned: 2
Workers Launched: 2
-> Parallel Seq Scan on foo (cost=0.00..135417.75 rows=1 width=37)
(actual time=2448.038..3706.009 rows=0 loops=3)
Filter: (i = 1000)
Rows Removed by Filter: 3333333
Planning Time: 0.353 ms
Execution Time: 3793.572 ms
(8 rows)
postgres=# commit;
COMMIT
postgres=# select xact_commit from pg_stat_database where datname =
'postgres';
xact_commit
-------------
161
(1 row)
--
Rahila Syed
Performance Engineer
2ndQuadrant
http://www.2ndQuadrant.com <http://www.2ndquadrant.com/>
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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