Re: Is mdextend really safe? - Mailing list pgsql-hackers

From Florian Weimer
Subject Re: Is mdextend really safe?
Date
Msg-id 827iac55c1.fsf@mid.bfk.de
Whole thread Raw
In response to Is mdextend really safe?  (Gregory Stark <stark@enterprisedb.com>)
List pgsql-hackers
* Gregory Stark:

> On Unix that creates a sparse file where the intervening blocks are
> not allocated. When we later write out those blocks the filesystem
> then has to allocate space for them.

This seems to happen relatively rarely.  Creating temporary holes like
this usually results in heavily fragmented files on the file systems I
use, and I don't see this with PostgreSQL.  (It's one of my gripes
with Berkeley DB.)

However, I looked at the code recently and couldn't figure out *why*
PostgreSQL's observed behavior is this way. 8-(

--
Florian Weimer                <fweimer@bfk.de>
BFK edv-consulting GmbH       http://www.bfk.de/
Kriegsstraße 100              tel: +49-721-96201-1
D-76133 Karlsruhe             fax: +49-721-96201-99


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