Re: Re: Idea: recycle WAL segments, don't delete/recreate 'em - Mailing list pgsql-hackers

From Bruce Momjian
Subject Re: Re: Idea: recycle WAL segments, don't delete/recreate 'em
Date
Msg-id 200107171914.f6HJEli25335@candle.pha.pa.us
Whole thread Raw
In response to Re: Idea: recycle WAL segments, don't delete/recreate 'em  (fche@redhat.com (Frank Ch. Eigler))
Responses Re: Re: Idea: recycle WAL segments, don't delete/recreate 'em  (Gunnar Rønning <gunnar@polygnosis.com>)
List pgsql-hackers
> Could you explain how postgresql can "fall victim" the filesystem hole
> mechanism?  Just hoping to force actual storage allocation, or hoping
> to discourage fragmentation?

Most Unix filesystems will not allocate disk blocks until you write in
them.  If you just seek out past end-of-file, the file pointer is moved
but the blocks are unallocated.  This is how 'ls' can show a 1gb file
that only uses 4k of disk space.

--  Bruce Momjian                        |  http://candle.pha.pa.us pgman@candle.pha.pa.us               |  (610)
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