Oracle Table Fragmentation

If only insert data into the table, table fragmentation will never happen. But if insert, update and delete are executed on a table frequently, table fragmentation will come out. If a table takes more disk space than its size, it is called table fragmentation. We could know this by querying USER_SEGMENTS and USER_TABLES.

Yesterday, customers complained that the disk is full. We found that one tablespace becomes very large, about 30G. Actually, no more than 10G data is contained in this tablespace. And I found one table uses approximate 20G, actually this table only has
2G data. Then I realize it is table fragmentation. We could avoid this kind of problem if using partition table.


How to handle table fragmentation? Refer to the links below.

http://www.orafaq.com/node/1936
http://oracle-online-help.blogspot.com/2007/02/identify-and-fix-table-fragmentation-in.html