From: "Geo." 

"Mike Nice"  wrote in message
news:p2h01v8m0a3idtgd4ksvr529oqoffggqf9{at}4ax.com...

>    The transaction log must contain a copy of all previous data; otherwise
how can it be used to
> apply changes as well as deletes - it must contain a copy of the data
before the change.

If I delete a file on disk, how can I undelete it if it's not logged then?

I don't think it stores the data, I think it stores the commands it
receives so if you send in a command to store "bob" in a name
field it stores the entire command including the data "bob" but
if you send it a command to delete all records with a name of
"bob" it only stores the command, marks the records as deleted
and possibly stores the record number as it deletes each record (but not
the data in the record). Now you can roll it back by unmarking those
records as deleted without having stored the data in the log file.

Geo.

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