INITIAL
Specify the size of the first extent of the object. Oracle allocates space for this extent when you create the schema object. Please refer to size_clause for information on that clause.
The default value is the size of 5 data blocks. In tablespaces with manual segment-space management, the minimum value is the size of 2 data blocks plus one data block for each free list group you specify. In tablespaces with automatic segment-space management, the minimum value is 5 data blocks. The maximum value depends on your operating system. Please refer to FREELIST GROUPS for information on freelist groups for more information.
In dictionary-managed tablespaces, if MINIMUM EXTENT was specified for the tablespace when it was created, then Oracle rounds the value of INITIAL up to the specified MINIMUM EXTENT size if necessary. If MINIMUM EXTENT was not specified, then Oracle rounds the INITIAL extent size for segments created in that tablespace up to the minimum value (see preceding paragraph), or to multiples of 5 blocks if the requested size is greater than 5 blocks.
In locally managed tablespaces, Oracle uses the value of INITIAL in conjunction with the size of extents specified for the tablespace to determine the first extent of the object. For example, in a uniform locally managed tablespace with 5M extents, if you specify an INITIAL value of 1M, then Oracle creates five 1M extents.
Restriction on INITIAL You cannot specify INITIAL in an ALTER statement.
NEXT
Specify in bytes the size of the next extent to be allocated to the object. Please refer to size_clause for information on that clause.
The default value is the size of 5 data blocks. The minimum value is the size of 1 data block. The maximum value depends on your operating system. Oracle rounds values up to the next multiple of the data block size for values less than 5 data blocks. For values greater than 5 data blocks, Oracle rounds up to a value that minimizes fragmentation, as described in Oracle Database Administrator's Guide.
If you change the value of the NEXT parameter (that is, if you specify it in an ALTER statement), then the next allocated extent will have the specified size, regardless of the size of the most recently allocated extent and the value of the PCTINCREASE parameter.
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