Oracle to xml question

Question

hi friends
i have a oracle table for country,city,town.
this table is like a tree
and it has 5000+ rows and has relation with some other tables
this datas fill into dropdown(combobox)if user select county from combobox1 ,combobox2 fill with this country's city and go on like this........
if i try convert table's datas to xml file and do querry from xml file instead of oracle table
do fill comboboxes work faster? or is it bad idea?

Answer 1

Well since I don't have a clue how you access the XML files generated and don't know how you access the tables in Oracle I can't tell you anything about performance with that level of detailed information. Still your approach sounds strange to me.
But what I can tell you is that I have doubts if you're understanding the implications of your current approach: If you're going to write to files in triggers then you might end up with files that are not consistent with the database content.
What will happen if the transaction that modifies the table is going to be rolled back (for whatever reason, you're not in control of all possible eventualities)?
Then you've written content to your file that doesn't reflect your database properly.
Also note that DML operations in Oracle under certain circumstances perform a so called "restart", which means that triggers might fire several times for each row.
A possible workaround for these issues is performing your non-transactional operation (send a mail, write to a file etc.) in job that is submitted in the trigger, because the job submit procedure is transactional and therefore is rolled back if a rollback occurs and therefore the job is never going to be executed in that case.
You can find more information about that issue e.g. by Tom Kyte here:
http://www.oracle.com/technology/oramag/oracle/08-jul/o48asktom.html
Regards,
Randolf
Oracle related stuff blog:
http://oracle-randolf.blogspot.com/
SQLTools++ for Oracle:
http://www.sqltools-plusplus.org:7676/
http://sourceforge.net/projects/sqlt-pp/