Name
ALTER CLUSTER
Synopsis
ALTER CLUSTER [schema.]cluster_name[PCTFREEinteger] [PCTUSEDinteger] [SIZEinteger[K | M]] [INITRANSinteger] [MAXTRANSinteger] [STORAGE ( [NEXTinteger[K | M] ] [MAXEXTENTS {integer| UNLIMITED} ] [PCTINCREASEinteger] [FREELISTSinteger] [FREELIST GROUPSinteger] ) ] [ALLOCATE EXTENT (SIZEinteger[K | M] [DATAFILE 'filename'] [INSTANCEinteger])] [DEALLOCATE UNUSED [KEEPinteger[K | M]] [PARALLEL ( {DEGREE {integer| DEFAULT} | INSTANCES {integer| DEFAULT} } ) ] [NOPARALLEL]
Redefines future storage allocations or allocates an extent for a cluster (cluster_name).
Keywords
- PCTFREE
Changes the percentage of space that will be kept free for future updates to the rows contained in this cluster. The value may be in the range - 99 and defaults to 10.
- PCTUSED
Changes the minimum percentage of used space that Oracle will maintain in each block. The value may be in the range - 99 and defaults to 40.
- SIZE
Determines how many cluster keys will be stored in each data block of this cluster. The value should be a divisor of the Oracle blocksize, and will be rounded up to the next larger divisor if necessary.
- INITRANS
Changes the number of transaction entries allocated to each block in the cluster. The value may be in the range 1-255 and should not normally be changed from the default of 2.
- MAXTRANS
Changes the maximum number of concurrent transactions that can update blocks of the cluster. The value may be in the range 1-255 and should not normally be changed from the default, which is a function of the Oracle blocksize.
- STORAGE
Specifies the physical characteristics of the cluster as follows:
- NEXT
Specifies the size of the next extent in bytes, kilobytes, or megabytes. If the value is not a multiple of the database blocksize, it will be rounded up to a multiple of the database blocksize.
- MAXEXTENTS
Specifies the maximum number of extents that may be allocated for this cluster. The default will vary according to the database blocksize. Specify UNLIMITED for unlimited expansion.
- PCTINCREASE
Specifies the percentage by which each extent will grow over the previous extent. The default is 50, which means that each extent will be one- and-one-half times larger than the previous extent.
- FREELISTS
Specifies the number of free lists contained in each freelist group in this cluster. The default is 1 and the maximum depends on the database blocksize.
- FREELIST GROUPS
Specifies the number of groups of free lists for this cluster. The default is 1. This parameter should be used only with the Parallel Server option running in parallel mode.
- ALLOCATE EXTENT
Forces the immediate allocation of the next extent.
- SIZE
Specifies the size of the new extent in bytes, kilobytes, or megabytes.
- DATAFILE
Specifies the name of the operating system datafile ( filename) in the tablespace in which this cluster resides to hold the new extent. If this value is omitted, Oracle will select a datafile.
- INSTANCE
Makes the new extent available to the specified instance, which is identified by the initialization parameter INSTANCE_NUMBER. This parameter can only be used when running in parallel mode.
- DEALLOCATE UNUSED
Releases storage above the highwater mark.
- PARALLEL
Specifies the level of parallelism to be supported, based on the following parameters:
- DEGREE
Specifies the degree of parallelism. An integer value specifies how many slave processes can be used. Specify DEFAULT to use the default value specified for the tablespace.
- INSTANCES
Specifies the number of instances that can be used to execute slave processes. Specify DEFAULT to use the default value specified for the tablespace.
- NOPARALLEL