Program 'defrag.pl' uses 5 main SQL statements to retrieve record sets which
  form the basis of generated DDL.  They are sometimes UNIONed, sometimes 
  MINUSed, etc., to refine the record sets.  The queries are:

  THE TABLESPACE -- the Tablspace named by the '--tablespace=<name>' argument.

  THE CONSTRAINTS -- provides a substitute for DBA_CONSTRAINTS, sans column
  SEARCH_CONDITION.

  THE TABLES -- provides a list of Owner/Table_name's which fully reside in
  THE TABLESPACE.  These are non-partitioned tables plus partitioned tables
  where every partition and subpartition reside in THE TABLESPACE.  This list 
  excludes IOT tables.

  THE IOTS -- provides a list of Owner/Table_name's which fully or partially
  reside in THE TABLESPACE.  In other words, if a partitioned IOT table has
  even one partition in THE TABLESPACE, it is included in this list.  Reasons
  these are in  a separate list from THE TABLES include the fact that their 
  Primary Key is part of the CREATE TABLE syntax, and there are never other 
  indexes on them,

  THE INDEXES -- provides a list of Owner/Index_name/Table_name's for indexes
  not belonging to THE TABLES but which fully or partially reside in THE
  TABLESPACE.  In other words, a partitioned index with even one partition in
  THE TABLESPACE is included in this list.

  The data in THE TABLES and THE IOTS will be exported, after which members of
  all 3 of the lists will be dropped before THE TABLESPACE is coalesced into
  as few as 1 extent per datafile.

  THE PARTITIONS -- provides Owner/Table_name/Partition_name/Segment_type's 
  for all partitions and subpartitions not belonging to THE TABLES nor to THE
  IOTS but which are located in THE TABLESPACE.  If any of these exist, the
  first step will be to perform a 'safety' export of their data directly from
  THE PARTITIONS.  Under normal circumstances, this export is not used.
  Rather, for each partition a corresponding 'temp' table is built matching
  the partition in structure, indexes and Primary Key.  The temp table is then
  EXCHANGED with the partition; this results in the temp table holding the
  data and the partition becoming empty.  The empty partition is moved to the
  alternate tablespace before the coalescing takes place.  The temp table is
  then treated like a member of THE TABLES (i.e., exported, dropped,
  recreated, indexed, imported, etc.).  After the temp table has its data
  imported, it is again EXCHANGED with its original partition, and thus the
  data once again becomes part of the table in its new, properly sized 
  segment.

  Note that nothing is done with indexes on the tables of THE PARTITIONS.  In
  the event that such an index or a partition thereof happens to reside in THE
  TABLESPACE, it will still be there after all other objects have been dropped 
  or moved eleehwhere.  Likewise, unless an alternate tablespace other than
  THE TABLESPACE is given (or if the named alternate tablespace does not
  exist), then the empty partition segments will also remain in THE TABLESPACE.
  If either of these conditions occurs, the THE TABLESPACE will not be
  completely empty when it is coalesced.  This is not necessarily a big
  problem, it is just not as clean as when THE TABLESPACE becomes completely
  empty before it is coalesced.

  The following descriptions of the 'Statement Groups' show the sequence of
  statments used to defragment THE TABLESPACE.  These DDL statements are in
  3 to 5 files.  Shell scripts are provided which perform the statements in
  the correct sequence, intermingled with the exports and imports.  The user
  should check the execution of each shell script for errors before continuing
  with the next step.  Within the SQL files, each group of statements is
  delineated by a header record which refers to a 'Statement Group Number'.
  These groups are defined below.
  
  EXPORT the data from THE PARTITIONS. (If all goes well, we won't use this.)
  
   1.  For each member of THE PARTITIONS:
         a.  Create a Temp table.
         b.  Add appropriate indexes.
         c.  Add a PK, if any.
         d.  EXCHANGE the Temp table with the partition.
         e.  MOVE the [now empty] Temp table to the alternate tablespace.
  
  EXPORT the data from THE TABLES, THE IOTS and the Temp tables.
  
   2.  DROP the Temp tables created in Group #1.
  
   3.  DROP all Foreign Keys referencing THE TABLES, THE IOTS or the tables
       of THE INDEXES.
  
   4.  DROP members of THE TABLES and THE IOTS.  Note: this DROPs all
       constrints on these tables.

   5.  DROP Primary Keys, Unique Constraints and Check Constraints on the
       tables of THE INDEXES. 

   6.  DROP members of THE INDEXES unless they enforce a Primay Key or Unique
       Constraint of the same name -- those that do disappeared in Group #5.
       Note: this will generate DROP INDEX statements for PK/UK's if the 
       Constraint name differs from the Index name (e.g., system generated
       names).  It won't cause any harm, but it will show an error in the log
       file spooled in SQL*Plus; these should be ignored.  Maybe we'll fix
       this someday.

   7.  CREATE the Temp tables.
  
   8.  CREATE members of THE TABLES and THE IOTS.

  IMPORT the data for THE TABLES, THE IOTS and the Temp tables.
  
   9.  CREATE indexes and PK's on the Temp tables.  EXCHANGE them with their
       corresponding partition, and DROP the now empty Temp tables.
  
  10.  CREATE indexes on THE TABLES, plus THE INDEXES themselves.

  11.  CREATE all Constraints on THE TABLES.

  12.  CREATE Check Cosntraints on THE IOTS.

  13.  CREATE Foreign Keys referencing THE TABLES, THE IOTS or the tables
       of THE INDEXES.

  14.  REBUILD non-partitioned or Global partitioned indexes on THE PARTITIONS
       (these were marked UNUSABLE during the partition EXCHANGE).

  ONLY IF PROBLEMS OCCURED DURING EXECUTION OF GROUP #1:

  15.  DROP the Temp tables.

  IMPORT the data for THE PARTITIONS.

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