In the original example it looks like using the index (and not running
a parallel query) is what made the query slow
The fast version was brute-force sequscan(s) + sort with 3 parallel
backends (leader + 2 workers) sharing the work.
On Tue, Mar 2, 2021 at 10:42 PM David Rowley wrote:
>
> On Wed
On Wed, 3 Mar 2021 at 10:04, Michael Lewis wrote:
> Are there guidelines or principles you could share about writing the group by
> clause such that it is more efficient?
If you have the option of writing them in the same order as an
existing btree index that covers the entire GROUP BY clause (i
>
> If we want to do anything much smarter than that like trying every
> combination of the GROUP BY clause, then plan times are likely going
> to explode. The join order search is done based on the chosen query
> pathkeys, which in many queries is the pathkeys for the GROUP BY
> clause (see standa
On Tue, 2 Mar 2021 at 21:53, Liu, Xinyu wrote:
> *Expected Behavior
>
> Since these two queries are semantically equivalent, we were hoping that
> PostgreSQL would evaluate them in roughly the same amount of time.
> It looks to me that different order of group by clauses triggers different
> pla
út 2. 3. 2021 v 9:53 odesílatel Liu, Xinyu napsal:
>
>
>
>
>
>
>
>
>
>
> * Hello, We have 2 TPC-H queries which fetch the same tuples but have
> significant query execution time differences (4.3 times). We are sharing a
> pair of TPC-H queries that exhibit this performance difference: First
> que
Hello,
We have 2 TPC-H queries which fetch the same tuples but have significant query
execution time differences (4.3 times).
We are sharing a pair of TPC-H queries that exhibit this performance difference:
First query:
SELECT "ps_comment",
"ps_suppkey",
"ps_supplycost",
t; Jinho Jung
>>
>> ____
>> From: MichaelDBA
>> Sent: Monday, March 1, 2021 8:04 AM
>> To: Jung, Jinho
>> Cc: pgsql-performa...@postgresql.org
>> Subject: Re: Potential performance issues
>>
>> Hi,
>>
>> It i
.com/
https://wiki.postgresql.org/wiki/Slow_Query_Questions
Regards
Pavel
> Thanks,
> Jinho Jung
>
> --
> *From:* MichaelDBA
> *Sent:* Monday, March 1, 2021 8:04 AM
> *To:* Jung, Jinho
> *Cc:* pgsql-performa...@postgresql.org
> *Subject:* Re:
we test again with the
performance-tuned PostgreSQL.
Hope we can contribute to improving PostgreSQL.
Thanks,
Jinho Jung
From: MichaelDBA
Sent: Monday, March 1, 2021 8:04 AM
To: Jung, Jinho
Cc: pgsql-performa...@postgresql.org
Subject: Re: Potential performa
On Mon, Mar 1, 2021 at 8:44 AM Bob Jolliffe wrote:
> Was just about to reply similarly. Mind you it perhaps does raise the
> question : are the default postgresql settings perhaps too
> conservative or too static. For example, in the absence of other
> explicit configuration, might it make more
Jung, Jinho schrieb am 28.02.2021 um 16:04:
> # Performance issues discovered from differential test
>
> For example, the below query runs x1000 slower than other DBMSs from
> PostgreSQL.
>
> select ref_0.ol_amount as c0
> from order_line as ref_0
> left join stock as ref_1
>
Was just about to reply similarly. Mind you it perhaps does raise the
question : are the default postgresql settings perhaps too
conservative or too static. For example, in the absence of other
explicit configuration, might it make more sense for many use cases
for postgres to assess the physical
Ha, Andrew beat me to the punch!
Andrew Dunstan wrote on 3/1/2021 7:59 AM:
On 2/28/21 10:04 AM, Jung, Jinho wrote:
# install DBMS
sudo su
make install
adduser postgres
rm -rf /usr/local/pgsql/data
mkdir /usr/local/pgsql/data
chown -R postgres /usr/local/pgsql/data
su - postgres
/usr/local/pgsql
Hi,
It is worthy work trying to compare performance across multiple database
vendors, but unfortunately, it does not really come across as comparing
apples to apples.
For instance, configuration parameters: I do not see where you are
doing any modification of configuration at all. Since DB
On 2/28/21 10:04 AM, Jung, Jinho wrote:
> # install DBMS
> sudo su
> make install
> adduser postgres
> rm -rf /usr/local/pgsql/data
> mkdir /usr/local/pgsql/data
> chown -R postgres /usr/local/pgsql/data
> su - postgres
> /usr/local/pgsql/bin/initdb -D /usr/local/pgsql/data
> /usr/local/pgsql/bin
# Performance issues discovered from differential test
Hello. We are studying DBMS from GeorgiaTech and reporting interesting queries
that potentially show performance problems.
To discover such cases, we used the following procedures:
* Install four DBMSs with the latest version (PostgreSQL, S
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