public inbox for [email protected]  

help / color / mirror / Atom feed

From: Mariel Cherkassky <[email protected]>
To: [email protected]
Subject: printing results of query to file in different times
Date: Thu, 24 Aug 2017 16:15:19 +0300
Message-ID: <CA+t6e1msXcLNKXc_AeVBWWzYCHxNK3LVP-bUgcia_LhsKQKbiA@mail.gmail.com> (raw)
List-Unsubscribe:  <mailto:[email protected]?body=unsub%20pgsql-performance>

I'm trying to understand what postgresql doing in an issue that I'm having.
Our app team wrote a function that runs with a cursor over the results of a
query and via the utl_file func they write some columns to a file. I dont
understand why, but postgresql write the data into the file in the fs in
parts. I mean that it runs the query and it takes time to get back results
and when I see that the results back postgresql write to file the data and
then suddenly stops for X minutes. After those x minutes it starts again to
write the data and it continues that way until its done. The query returns
total *100* rows. I want to understand why it stops suddenly. There arent
any locks in the database during this operation.

my function looks like that :

func(a,b,c...)

cursor cr for

select ab,c,d,e.....

begin

raise notice - 'starting loop time - %',timeofday();

 for cr_record in cr

    Raise notice 'print to file - '%',timeofday();

    utl_file.write(file,cr_record)

 end loop

end

I see the log of the running the next output :

starting loop 16:00

print to file : 16:03

print to file : 16:03

print to file : 16:07

print to file : 16:07

print to file : 16:07

print to file : 16:010

......



Can somebody explain to me this kind of behavior ? Why is it taking some
much time to write and in different minutes after the query already been
executed and finished ? Mybe I'm getting from the cursor only part of the
rows ?

reply

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Reply to all the recipients using the --to and --cc options:
  reply via email

  To: [email protected]
  Cc: [email protected]
  Subject: Re: printing results of query to file in different times
  In-Reply-To: <CA+t6e1msXcLNKXc_AeVBWWzYCHxNK3LVP-bUgcia_LhsKQKbiA@mail.gmail.com>

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

This inbox is served by agora; see mirroring instructions
for how to clone and mirror all data and code used for this inbox