<Accessing|using> .log and .xac files?

[Geert Janssens]

On Thursday 1 July 2010, Felix Karpfen wrote:
> A hypothetical!
> 
> When installing gnucash, I opted to retain the automatically-created
> .log and .xac files for 5 days.
> 
> To date, I have never needed to use them.  Is there any documentation
> that shows when and how these files can be used?
> 
> Felix Karpfen
> 
I'm not sure there is much information on this, but here's a short intro:

* The .xac backup files are regular gnucash files. You can open them just like 
your main data file. GnuCash creates these at regular time intervals 
(configurable via Preferences), simply by executing the equivalent of a "Save 
As..." command. Should your main datafile become corrupted, you can replace it 
with one of these backup files (via a standard filesystem copy/paste) and 
continue from there. You will of course have to redo the work since the backup 
file was created.
* the .log files record (in real time) any transaction 
addition/modification/removal since the last time your data file was saved. It 
is meant as a last resort recovery method in case GnuCash quit unexpectedly, 
although in my opinion it's a bit limited in scope for that. If you happen to 
have a crash, you can open your last saved file and then "replay" the most 
recent log file via File->Import->Replay GnuCash .log file.
It's limited in scope because
a. In only logs transactions, and not anything else, like account 
creation/modification/removal, business objects, budgets,...
b. some transactions are locked (for example reconciled transactions or 
transactions related to invoices/bills), and the replay code doesn't deal very 
well with that.

Note that .log files are only relevant for the current (xml) data file format. 
2.4 will introduce 3 new formats (sqlite3 file, mysql database and postgres 
database) next to the current one. These three new formats will save each 
modification in real-time, so logging won't be needed anymore.

Geert