Re: Recovering data via raw table and field separators - Mailing list pgsql-general

From Martijn van Oosterhout
Subject Re: Recovering data via raw table and field separators
Date
Msg-id 20071204185854.GC19536@svana.org
Whole thread Raw
In response to Re: Recovering data via raw table and field separators  (Alvaro Herrera <alvherre@alvh.no-ip.org>)
Responses Re: Recovering data via raw table and field separators
List pgsql-general
On Tue, Dec 04, 2007 at 03:38:16PM -0300, Alvaro Herrera wrote:
> > So is it simply field width? Can one count the number of bytes based
> > on native datatype length and determine field start/end?
>
> Yes.  For variable length types, there is a 4-byte length word at the
> start of the field (unless you are using 8.3 which introduces more
> compact representations in some cases).

And NULLs are skipped entirely. They are represented in the null-bitmap
at the beginning of the tuple.

What sometimes works is creating a new table with the exact same
structure, shutting down the postmaster and copying the old table over
the new one. If it's the same cluster and the clog/xlog are still there
it might work.

Have a nice day,
--
Martijn van Oosterhout   <kleptog@svana.org>   http://svana.org/kleptog/
> Those who make peaceful revolution impossible will make violent revolution inevitable.
>  -- John F Kennedy

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