To quickly move big tables between schemas
I use EXCHANGE PARTITION feature of Oracle 8i.

for example:

SQL> connect as user "A"

SQL> create table large_table
     (
       a number,
       b char,
       c date
     )

-- just for this example only. :)
SQL> grant ALL on large_table to "B";



SQL> connect as user "B"

SQL> create table large_table 
     (
       a number,  
       b char,    
       c date
     )
     partition by range (a)
     (
       partition dummy values less than (maxvalue)
     )





Then you can use the following command to quickly move 
"A.large_table" to "B.large_table"

SQL> connect as user "B";

SQL> alter table large_table exchange partition dummy
     with table A.large_table;

And return it back to schema A:

SQL> alter table large_table exchange partition dummy
     with table A.large_table;
-- of course, it is the same SQL command

 

The exchange partition idea by one of the readers was nice. But I didnt quite get

"Then you can use the following command to quickly move 
"A.large_table" to "B.large_table"

SQL> connect as user "B";

SQL> alter table large_table exchange partition dummy
     with table A.large_table;

And return it back to schema A:

SQL> alter table large_table exchange partition dummy
     with table A.large_table;
-- of course, it is the same SQL command"


The first one does what is needed i.e. put a.large_table into the dummy partition.

Why is the second alter table needed? 

How about using either of these two methods to exclude large tables during export.

Method 1: (Dangerous but still can be used with due care)
Modifying (After taking backup) View  SYS.EXU9TABU - Oracle 9i or SYS.EXU81TABU - Oracle 8i

create table t_small (a number);

create table t_large (a number);

insert into t_small select rownum from all_objects where rownum < 11;

10 rows created.

insert into t_large select rownum from all_objects;

36347 rows created.

SQL> commit;

Commit complete.

SQL> host exp test/test file=test.dmp log=test.log owner=test
Connected to: Oracle9i Enterprise Edition Release 9.2.0.5.0 - 64bit Production

About to export specified users ...
<output truncated>
 about to export TEST's tables via Conventional Path ...
. . exporting table                        T_LARGE      36347 rows exported
. . exporting table                        T_SMALL         10 rows exported
. . .
<output truncated>

Export terminated successfully without warnings.
---Now connect as SYS
SQL> conn / as sysdba
Connected.
SQL> create or replace VIEW SYS.EXU9TABU ( OBJID, DOBJID, NAME, OWNER, OWNERID, TABLESPACE, TSNO, FILENO, BLOCKNO, AUDIT$, COMMENT$, CLUSTERFLAG, MTIME, MODIFIED, TABNO, PCTFREE$, PCTUSED$, INITRANS, MAXTRANS, DEGREE, INSTANCES, CACHE, TEMPFLAGS, PROPERTY, DEFLOG, TSDEFLOG, ROID, RECPBLK, SECONDARYOBJ, ROWCNT, BLKCNT, AVGRLEN, TFLAGS, TRIGFLAG, OBJSTATUS ) AS
SELECT  "OBJID","DOBJID","NAME","OWNER","OWNERID","TABLESPACE","TSNO","FILENO","BLOCKNO","AUDIT$","COMMENT$","CLUSTERFLAG","MTIME","MODIFIED","TABNO","PCTFREE$","PCTUSED$","INITRANS","MAXTRANS","DEGREE","INSTANCES","CACHE","TEMPFLAGS","PROPERTY","DEFLOG","TSDEFLOG","ROID","RECPBLK","SECONDARYOBJ","ROWCNT","BLKCNT","AVGRLEN","TFLAGS","TRIGFLAG","OBJSTATUS"
FROM    sys.exu9tab
WHERE   ownerid = UID
and name not in('T_LARGE');  <<== To exclude Large table

View created.

SQL> host exp test/test file=test_one.dmp log=test_one.log owner=test

About to export specified users ...
. about to export TEST's tables via Conventional Path ...
<output truncated> 

. . exporting table                        T_SMALL         10 rows exported

<output truncated>
Export terminated successfully without warnings.

After the export recreate the view without 
" and name not in('T_LARGE') " condition

Method 2 : Using FGAC

CREATE OR REPLACE FUNCTION hide_table(p_schema varchar2, p_table varchar2) RETURN varchar2 is
user_context varchar2(1000);
BEGIN
IF SYS_CONTEXT('USERENV','SESSION_USER')='TEST' THEN
 user_context := '1=2'
ELSE USER_CONTEXT := '';
END IF:
RETURN USER_CONTEXT;
END hide_table;

--Add Policies to hide the rows in table T_LARGE
execute dbms_rls.add_policy('TEST','T_LARGE',NO_EXPORT','TEST','HIDE_TABLE');

 Now if we export the schema TEST, zero rows for T_LARGE table is exported. After the export drop the policy

execute dbms_rls.drop_policy('TEST','T_LARGE','NO_EXPORT');


Do remember to change the view or drop the policy immediately after the export.

 

sql> create table source_partitioned
    ( a number,  b varchar2(1),    c date)
     partition by range (c)
    ( partition p1 values less than (date '2009-01-01')
    , partition pmax values less than (maxvalue)
    );
sql> create table target_partitioned
    ( a number,  b varchar2(1),    c date)
     partition by range (c)
    ( partition p1 values less than (date '2009-01-01')
    , partition pmax values less than (maxvalue)
    );
sql> create table partition_holder ( a number, b varchar2(1) , c date );
sql> insert into source_partitioned values ( 1, 1, date '1998-01-01');
sql> insert into source_partitioned values ( 2, 2, sysdate);
sql> alter table source_partitioned exchange partition p1 with table partition_holder;
sql> alter table target_partitioned exchange partition p1 with table partition_holder;
sql> select * from source_partitioned;

         A B C
---------- - -------------------
         2 2 2009-11-28 16:54:12
sql> select * from target_partitioned;

         A B C
---------- - -------------------
         1 1 1998-01-01 00:00:00
sql> alter table source_partitioned exchange partition pmax with table partition_holder;
sql> alter table target_partitioned exchange partition pmax with table partition_holder;
sql> select * from source_partitioned;
sql> select * from target_partitioned;

         A B C
---------- - -------------------
         1 1 1998-01-01 00:00:00
         2 2 2009-11-28 16:54:12

BEGIN
FOR REC IN (
  SELECT partitioN_name
    FROM dba_tab_partitions
   WHERE table_owner = 'SRC'
     AND Table_name = 'XCOVERAGE'
     AND partition_name between 'PAR_1998_02'
                            and 'PAR_2009_09'
   ORDER BY 1 ) LOOP
  -- move partition from source to temp
  EXECUTE IMMEDIATE
    ' alter table src.xcoverage exchange partition '
    ||rec.partition_name||'  with table dpg_cvg_tmp';
  -- move partition from temp to target
  EXECUTE IMMEDIATE
    ' alter table dpg_cvg_par exchange partition '
    ||rec.partition_name||' with table dpg_cvg_tmp';
END LOOP;
END;
/
Elapsed: 00:08:13.59
select count(*) from src.xcoverage;

       COUNT(*)
---------------
              0
Elapsed: 00:00:01.60
d1:cidw\cidwwrite> select count(*) from dpg_cvg_par;

       COUNT(*)
---------------
    167,074,754
Elapsed: 00:00:51.93