Re: Quickly unload (export) large Oracle table into text flat file

Pratap wrote:

>
> Can't believe any software other than Oracle can read directly from
> the data files. They have to use SQL.
>
> Pratap

A very long time ago (Oracle6 era) I needed to retrieve data from the underlying (corrupted) datafiles of a database. Wrote a small C program to read through the datafiles and extracted the data. The same concepts still work today.

However there have been enough changes that I would seriously question the reliability/accuracy of data extracted from the data files in anything but the simplest cases. It would take a serious, and ongoing, effort to keep up with the Oracle internals.

Some examples of issues include: chaining; LOBs; new data types such as XML, spatial, interval; the internal hoops used for Object types. (Which, aside from being annoyed at how close this was to spam, was the reason for my original response.)

Then again, many though it impossible to read the redo log files. Along came a third party and created LOGMINER. Thankfully bought out by and now maintained by Oracle, as useful stuff usually is.

So generally not worth the effort unless you are very, very serious - or very, very stuck.

/Hans Received on Tue Aug 31 2004 - 16:49:41 CEST