Re: About tapes - Mailing list pgsql-hackers

From Robert Haas
Subject Re: About tapes
Date
Msg-id AANLkTinERwYkDbw-EFuuUQo1R5YfhSiFIAQ_s_UwyRiB@mail.gmail.com
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In response to About tapes  ("mac_man2005@hotmail.it" <mac_man2005@hotmail.it>)
Responses Re: About tapes  ("mac_man2005@hotmail.it" <mac_man2005@hotmail.it>)
List pgsql-hackers
On Fri, Jun 18, 2010 at 2:36 PM, mac_man2005@hotmail.it
<mac_man2005@hotmail.it> wrote:
> Please take a look at the initial comment contained into the logtape.c file:
> http://doxygen.postgresql.org/logtape_8c-source.html
>
> Almost at the beginning of that file, it is affirmed that implementing tapes
> on disk (quote: by creating a separate file for each "tape") will require
> more space than implementing merge on tapes themselves.
> Now, taking in account that tuplesort.c and logtape.c actually DO implement
> tapes on disk, in which case it would require between 2x and 4x the input
> space?

Did you read the rest of the comment?  It explains how the code avoids this...

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise Postgres Company


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