При попытке выполнить

ALTER TABLE xxx SHRINK SPACE [COMPACT] [CASCADE]

получаю ошибку — ORA-10631: SHRINK clause should not be specified for this object.

Вот выдержка из документации shrink_clause, ограничения для выполнения команды. Эти ограничения могут служить причиной ошибки ORA-10631.

Restrictions on the shrink_clause The shrink_clause is subject to the following restrictions:

• You cannot combine this clause with any other clauses in the same ALTER TABLE statement.
• You cannot specify this clause for a cluster, a clustered table, or any object with a LONG column.
• Segment shrink is not supported for tables with function-based indexes, domain indexes, or bitmap join indexes.
• This clause does not shrink mapping tables of index-organized tables, even if you specify CASCADE.
• You cannot specify this clause for a compressed table.
• You cannot shrink a table that is the master table of an ON COMMIT materialized view. Rowid materialized views must be rebuilt after the shrink operation.