compression of tables

From: slim <sfar_Selim_at_excite.com>
Date: 23 Apr 2002 08:25:59 -0700
Message-ID: <16e3a9da.0204230725.251c0139@posting.google.com>

Hi,

suppose that we have 4 tables:

--> t1 : t1_id (pk), t1_info
--> t2 : t2_id (pk), t2_info, t2_t1_id (foreign key)
--> t3 : t3_id (pk), t3_info, t3_t1_id (foreign key)

Suppose that we have 1 millions of records in t1,

                     5 millions of records in t2,
                     4 millions of records in t3

the goal is to compress these data in this case we process like this

If n ( n > 1) records in t1 have the same t1_info, and the same set of info in both tables

            t2 and t3 then we will delete cascade (n-1) rows from t1

e.g. :

 t1 :  t1_id           t1_info
         1             'car'
         2             'car'
         3             'car' 
         4             'van'
 t2 : t2_id           t2_info      t2_t1_id
        1              'tyre'         1
        2              'brake'        1  
        3              'tyre'         2
        4              'brake'        2
        5              'tyre'         3
        6              'brake'        3
        7              'capacity'     4

 t3 : t3_id           t3_info      t2_t1_id
        1              'price'        1
        2              'power'        1  
        3              'price'        2
        4              'power'        2
        5              'price         3
        6              'power'        3
        7              'power'        4

  In this case we delete on cascade only t1_id = 2 and t1_id = 3 from t1

  I am writing the function and I have a big problem of performance,   You are helpful for each idea you give to me!

     thanks .. Received on Tue Apr 23 2002 - 10:25:59 CDT