[GNC-dev] Bug 797463 - CSV Import of transactions into a new file hangs

[Christian Gruber]

I have some questions related to Bug 797463 
<https://bugs.gnucash.org/show_bug.cgi?id=797463>, which I have analyzed.

The author wrote, that "Gnu Cash hangs", when importing (only two) 
transactions into a Gnu Cash file with standard accounts list SKR04.

My analysis showed, that actually Gnu Cash does not hang, but needs 
really long time for import (several minutes). The problem is, that the 
author has bayesian matching enabled in his preferences, but the Gnu 
Cash file is not prepared for bayesian matching (feature 
GNC_FEATURE_GUID_FLAT_BAYESIAN is not set in the Gnu Cash file). 
Moreover the Gnu Cash file contains a lot of accounts (approx. 1000).

Most time is spent in function check_import_map_data(), which is called 
from gnc_account_imap_find_account_bayes() (Account.cpp). In this 
function imap_convert_bayes_to_flat() is called, which AFAICS prepares 
all accounts for bayesian matching.

I'm not familiar with that conversion step and therefore have several 
questions:

Why does the conversion need so much CPU time?

If the conversion needs so much CPU time, why is it done only 
temporarily? The conversion is done for each of the two transactions again.

Why is the conversion even not persistent after the import is done? The 
feature GNC_FEATURE_GUID_FLAT_BAYESIAN is not set in the Gnu Cash file, 
even not after the import is finished.

Regards,
Christian