Re: Copy command Faster than original select

I think, it is the difference between writing 43602 records into the file and displaying 43602 records on screen.
If you wrap up your select into select count(a.*) from your select, e.g.:

Select count(a.*) from (select ... from mytable join .. join ... order by ....) as a;

This will exclude time to display all these rows, so you'll get the same (or better) performance as with "copy" into
textfile, which will prove this theory. 

Regards,
Igor Neyman

-----Original Message-----
From: pgsql-performance-owner@postgresql.org [mailto:pgsql-performance-owner@postgresql.org] On Behalf Of belal
Sent: Friday, February 06, 2015 3:31 AM
To: pgsql-performance@postgresql.org
Subject: [PERFORM] Copy command Faster than original select

I made complex select using PGAdmin III Query Editor, Postgre server 9.3


select ... from mytable join .. join ... order by ....

I get [Total query runtime: 8841 ms. 43602 rows retrieved.]

but when I use

copy ([same above select]) to '/x.txt'
I get [Query returned successfully: 43602 rows affected, 683 ms execution time.]

these test made on the same machine as the postgresql server.


can anyone explain huge difference in executing time?

best regards all



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