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From:Johan De Meersman Date:February 10 2009 9:06am
Subject:Re: using Unix soft links
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On Mon, Feb 9, 2009 at 6:10 PM, Lucio Chiappetti <lucio@stripped>wrote:

> I used to make Unix soft links of mysql tables back on mysql 3.23.
>
> [...]
>

> But I wonder if there is anything intrinsically wrong in the usage of
> soft-links, or whether this might be an indication instead of hardware
> problems with our machine or disks !



In short, the mysql server will cache the metadata of the tables, and, thus,
for xxx and xxxdup separately. Any modification to xxx will not immediately
come throught in xxxdup, but depending on the updates to xxx, you might
suddenly have to read data from the file and end up with not quite what you
expected.

Thus, you see 'corruption' in xxxdup. You run a repair on it, which for some
reason modifies the file, so now the cached metadata for xxx is incorrect.

Rinse and repeat until all your data is fucked over.


You really want to do this with views, or triggers to update the duplicate
table, or, if all else fails, scheduled 'create table as select' statements.


-- 
Celsius is based on water temperature.
Fahrenheit is based on alcohol temperature.
Ergo, Fahrenheit is better than Celsius. QED.

Thread
optimizing UNIONs ?Lucio Chiappetti10 Jun
  • using Unix soft linksLucio Chiappetti9 Feb
    • Re: using Unix soft linksJohan De Meersman10 Feb
Re: optimizing UNIONs ?Lucio Chiappetti11 Jun