Oracle Database 11g The Complete Reference (Osborne ORACLE ...

Chapter 51: The Hitchhiker’s Guide to Database Administration 873
Next, have Oracle move rows within the table to compress the allocation of rows within blocks:
alter table BOOKSHELF_CHECKOUT shrink space compact;
The shrink space compact operation will reorganize the rows of the table so they are stored
more compactly. However, the high-water mark for the table—the highest block number to which
rows have ever been written—is unaffected. Since all full table scans will read all blocks up to the
high-water mark, you should adjust that value. You can adjust the high-water mark via the shrink
space clause of the alter table command. For example:
alter table BOOKSHELF_CHECKOUT shrink space;
You can cascade the effects of this change to the table’s indexes via the shrink space cascade
option.
To predict space usage, you can use the OBJECT_GROWTH_TREND function of the DBMS_
SPACE package. As parameters, pass the schema name, object name, and object type, as shown
in the following listing. You should run this as a SYSDBA-privileged user.
select * from
table(DBMS_SPACE.OBJECT_GROWTH_TREND
('PRACTICE','BOOKSHELF_CHECKOUT','TABLE'));
The output will show the past space usage for the object along with projected space
requirements for the object. The results are based on statistics gathered via the Automated Workload
Repository (AWR). Using the MMON background process, AWR collects and stores database
statistics that support administration and tuning on an hourly basis. The information gathered via
AWR allows Oracle to project your future space usage as well as identify tuning opportunities.
Transporting Tablespaces
A transportable tablespace is a tablespace that can be “unplugged” from one database and
“plugged into” another. To be transportable, a tablespace—or a set of tablespaces—must be
self-contained. The tablespace set cannot contain any objects that refer to objects in other
tablespaces. Thus, if you transport a tablespace containing indexes, you must move the tablespace
containing the indexes’ base tables as part of the same transportable tablespace set. The better
you have organized and distributed your objects among tablespaces, the easier it is to generate
a self-contained set of tablespaces to transport.
To transport tablespaces, you need to generate a tablespace set, copy or move that tablespace
set to the new database, and plug the set into the new database. The databases must be on the
same operating system, with the same version of Oracle and character set.
Generating a Transportable Tablespace Set
A transportable tablespace set contains all of the datafiles for the tablespaces being moved, along
with an export of the metadata for those tablespaces. You can optionally choose whether to include
referential integrity constraints as part of the transportable tablespace set. If you choose to use
referential integrity constraints, the transportable tablespace set will increase to include the tables
required to maintain the key relationships. Referential integrity is optional because you may have
the same code tables in multiple databases. For example, you may be planning to move a
tablespace from your test database to your production database. If you have a COUNTRY table
in the test database, then you may already have an identical COUNTRY table in the production