Performance of UNION vs alternative

[James]

I have four tables.
These four tables save information from 4 different user 
activities...so they save 4 very different data sets.  (for example, 
one activity could be choosing different tracks to make a song, and 
another activity could be choosing different clipart to make a 
collage)

However, they have columns in common...such as 
'title_of_composition', 'date_saved', 'description', and 'approved'.
I need to first do a query to list these saved records and display 
their 'title' and the 'date_saved'.
Then when the user clicks on one of these records, I would do another 
query to display all of the saved data, including activity specific 
data.

I was wondering which method of querying these saved records would 
yield the best performance.

METHOD A:
I can stay with these 4 tables and use a UNION :
SELECT record_id, title_of_composition, date_saved, 'song' as 
data_table FROM song WHERE description like '%cat%'
UNION
SELECT record_id, title_of_composition, date_saved , 'collage' as 
data_table FROM collage WHERE description like '%cat%'
UNION
...etc.

Now I will get a list of all records from the 4 tables that mentions 
'cat' in the description.  I also have enough information 
(data_table, and record_id) so that I can grab all the details from 
the right table later.


METHOD B:
I create another table 'all_compositions' that will hold:
'title_of_composition', 'date_saved', 
'description'(...also,'data_table', and 'data_table_record_id')

For the other 4 tables, I remove these columns, so they only hold the 
specific details of the activity.

Now when I do the first query, all I have to do is:
SELECT record_id, title_of_composition, date_saved, data_table, 
data_table_record_id WHERE description like '%cat%;

Now I will have the necessary information to access the details of 
each activity when one of these records is selected.


PERFORMANCE-wise, which is better?  METHOD A using the UNION, or 
METHOD B, with a slight database modification.

DATABASE DESIGN-wise which is better?
Thanks!
--
-James
--
MySQL General Mailing List
For list archives: http://lists.mysql.com/mysql
To unsubscribe:    http://lists.mysql.com/[EMAIL PROTECTED]