Ensuring no data movement when you attach a fragment

For example, you might create a fragmented table and index with the following SQL statements:

CREATE TABLE tb1(a int) 
   FRAGMENT BY EXPRESSION
      (a >=0 AND a < 5) IN db1,
      (a >=5 AND a <10) IN db2;

CREATE INDEX idx1 ON tb1(a);

Suppose you create another table that is not fragmented, and you subsequently decide to attach it to the fragmented table.

CREATE TABLE tb2 (a int, check (a >=10 and a<15)) 
   IN db3; 

CREATE INDEX idx2 ON tb2(a) 
   IN db3;         

ALTER FRAGMENT ON TABLE tb1 
   ATTACH 
      tb2 AS (a >= 10 AND a<15) AFTER db2;

This ALTER FRAGMENT ATTACH operation takes advantage of the existing index idx2 because the following steps were performed in the example to prevent data movement between the existing and the new table fragment:

• The check constraint expression in the CREATE TABLE tb2 statement is identical to the fragment expression for table tb2 in the ALTER FRAGMENT ATTACH statement.
• The fragment expressions specified in the CREATE TABLE tb1 and the ALTER FRAGMENT ATTACH statements are not overlapping.