Strange result of select

Hi,
i do this select joined in 2 tables for have number of block and byte from user_tables and user_segment.

SELECT A.BYTES,A.BLOCKS,B.BLOCKS

     FROM USER_EXTENTS A, USER_TABLES B
     WHERE B.TABLE_NAME = 'PROVA'
     AND A.SEGMENT_NAME='PROVA';


BYTES     BLOCKS      BLOCKS
-----  ---------    --------
65536         16          13

the same table have 16 blocks in user_extents and 13 in user_tables, why??

THANKS!
andrew Received on Mon Apr 09 2007 - 11:54:24 CDT