Question: What is the "freepools" parameter
of the LOB definitions of the alter table command?
alter table [tablename] modify lob ([clob
name]) (freepools [n]);
Answer: Oracle
notes that the freepools defines the number of
freelists for LOB segments attached to the table. Just
as freelists are used to manage free data blocks (and bitmap
freelists if using Automatic segment space management
(ASSM)), the freepools.
Oracle notes that the LOB segment freepools is
related to the
automatic undo mode and you can specify freepools
only if the database is running in automatic undo mode.
The default value for freepools is 1, except for RAC where
the freepools will equal the number of RAC instances.
In this sense, freepools is analogous to the
freelist_groups parameter, set at one per instance.
Consequently, you cannot specify both freepools and
the freelist groups parameter of the table
"storage" clause.
For details on optimizing the freepools parameter for LOB
segments, see MISC note 365156.1 "Rebuilding LOB freepools".
Also beware of
Bug 4450606 before making any changes to the
freepools parameters as this might cause serious LOB
corruption.
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