Re: [HACKERS] Slow count(*) again...

Vitalii Tymchyshyn <tivv00@gmail.com>

From: Віталій Тимчишин <tivv00@gmail.com>

To: david@lang.hm

Cc: Robert Haas <robertmhaas@gmail.com>, Jon Nelson <jnelson+pgsql@jamponi.net>, Mladen Gogala <mladen.gogala@vmsinfo.com>, Andrew Dunstan <andrew@dunslane.net>, Bruce Momjian <bruce@momjian.us>, Tom Lane <tgl@sss.pgh.pa.us>, Craig Ringer <craig@postnewspapers.com.au>, "pgsql-performance@postgresql.org" <pgsql-performance@postgresql.org>

Date: 2011-02-04T07:39:38Z

Lists: pgsql-hackers, pgsql-performance

4 лютого 2011 р. 09:32 <david@lang.hm> написав:

>
>
> when a copy command is issued, I assume that there is some indication of
> how much data is going to follow. I know that it's not just 'insert
> everything until the TCP connection terminates' because that would give you
> no way of knowing if the copy got everything in or was interrupted part way
> through. think about what happens with ftp if the connection drops, you get
> a partial file 'successfully' as there is no size provided, but with HTTP
> you get a known-bad transfer that you can abort or resume.
>
> I don't think so, since you can do 'cat my_large_copy.sql | psql'. AFAIR it
simply looks for end of data marker, either in protocol or in stream itself
(run copy from stdin in psql and it will tell you what marker is).



-- 
Best regards,
 Vitalii Tymchyshyn