View Full Version : Merge

02-12-2004, 12:18 AM
I'm investigating the suitability of using PhpDig as part of the eLearning platform for the Ghent University (Belgium).

If I were to give each professor his/her own PhpDig environment and database, which would give the professor full control on what to index for the course and when, how difficult would it be to merge several course-specific PhpDig database tables into big ones, allowing to perform searches across courses?

02-13-2004, 11:37 AM
Hi. The following link outlines some problems with merging tables:


02-16-2004, 02:42 AM
Thanks. I wasn't aware of the existence of MERGE tables yet.

If, in the situation sketched above, I created MERGE tables, they would be ReadOnly, as I only want to provide a global Search. Indexing would only be done in the subtables.

Correct me where I'm wrong. A Search is roughly done as follows: the query words entered by the user are looked up in the keywords table, giving key_ids that the engine table can translate in spider_ids, which correspond to URLs of pages where the query words occur.

For this to work correctly with MERGE tables, there should not be overlaps between the values used for key_id in the merged subtables, similarly for spider_id values etc.

These are AUTO_INCREMENT fields and there is a user comment in the MySQL manual stating how to set an initial value for an AUTO_INCREMENT field:

So it would seem to me that if we define the subtables with widely separated start values for these id fields, a global Search on MERGE tables might function!

What do you think?

02-16-2004, 01:49 PM
Hi. My thought is to try it on a demo and see how it works.