Import problem: What is the importance of the table 'importexport_importdata', can i truncate it and what is it good for anyhow?

Question

i have a problem with a clients Magento DB while trying to replicate it on my computer.

Needless to say that i was not able to export the DB via the Magento Backend (using 1.6 Community version), that crashed the customers page somehow blocking some DB tables (never figured out what exactly happened, gave me 1205 errors on the *log_visitor* table when trying to login, but after some DB maintenance it worked again). So i finally managed to export the whole db with the great Adminer script (in chunks, exporting the logs and product tables separately).

So the current situation:

Export via Adminer works like a charm.

Import gives me an error while trying to import the mentioned 'importexport_importdata' table which only has one entry but with a size of ~2.5 MB ! So while i was able to work around the huge size of the clients log and product tables (between ~250k and ~800k entries) by exporting them separatedly, i just can't import that table because its only entry is simply to big to import in one chunk.

I could cut the import of this entry to smaller pieces and simply append them to the entry, but i read on one page that this table could be truncated which i would prefer todo. The problem is that i haven't found much information about this table at all and am reluctant to truncate it without having more information about it.

QUESTION is it really save to truncate this table and what purpose does the data stored in it serve?

Answer 1

I my opinion it is safe to truncate this table as even the magento db backup system ignores it. See Mage_Backup_Model_Db as it has a list of data tables to ignore that the import data table is the only one in this.

protected $_ignoreDataTablesList = array(
    'importexport/importdata'
);

I would test this locally and as always make sure you have a full database backup (not via magento) before doing anything like this in the database.