Impossible compression ratio on ZFS
numisemis at gmail.com
Mon Jun 13 09:29:08 UTC 2011
2011/6/13 Steven Hartland <killing at multiplay.co.uk>
> I've just done an optimisation of a mysql table which is located
> on a compressed zfs partition and spotted that the size reported
> by du is impossibly small for the file:-
> du -h detail*
> 1.5K detail.frm
> 7.5K detail.ibd
> ls -l detail*
> -rw-rw---- 1 mysql mysql 8660 Jun 13 10:00 detail.frm
> -rw-rw---- 1 mysql mysql 650117120 Jun 13 10:04 detail.ibd
> The table format for those interested is 3 int's, 3 indexes and
> contains 8million rows.
> I highly doubt that my 620MB table is taking up just 7.5K on disk
> any ideas?
It is possible if the file detail.ibd is mostly filled with zeros (that
would be the case unless you have 620MB of real data).
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