Release 1 (9.0.1)
Part Number A90125-01
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| Oracle9i SQL Reference Release 1 (9.0.1) Part Number A90125-01 |
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SQL Statements:
ALTER CLUSTER to ALTER SEQUENCE, 6 of 18
Use the ALTER INDEX statement to change or rebuild an existing index.
The index must be in your own schema or you must have ALTER ANY INDEX system privilege.
To execute the MONITORING USAGE clause, the index must be in your own schema.
To modify a domain index, you must have EXECUTE object privilege on the indextype of the index.
Schema object privileges are granted on the parent index, not on individual index partitions or subpartitions.
You must have tablespace quota to modify, rebuild, or split an index partition or to modify or rebuild an index subpartition.
alter_index::=
alter_index
deallocate_unused_clause
allocate_extent_clause
parallel_clause
physical_attributes_clause
storage_clause: See storage_clause.
rebuild_clause
compression_clauses::=
compression_clauses
alter_index_partitioning
modify_index_default_attrs
modify_index_partition
rename_index_partition
drop_index_partition
split_index_partition
index_partition_description::=
index_partition_description
modify_index_subpartition
Specify the schema containing the index. If you omit schema, Oracle assumes the index is in your own schema.
Specify the name of the index to be altered.
Restrictions:
index is a domain index, you can specify only the PARAMETERS clause, the RENAME clause, or the rebuild_clause (with or without the PARAMETERS clause). No other clauses are valid.
LOADING or FAILED. If an index is marked FAILED, the only clause you can specify is REBUILD.
The deallocate_unused_clause lets you explicitly deallocate unused space at the end of the index and makes the freed space available for other segments in the tablespace. Only unused space above the high water mark can be freed.
If index is range-partitioned or hash-partitioned, Oracle deallocates unused space from each index partition. If index is a local index on a composite-partitioned table, Oracle deallocates unused space from each index subpartition.
Restrictions:
rebuild_clause.
The KEEP clause lets you specify the number of bytes above the high water mark that the index will have after deallocation. If the number of remaining extents are less than MINEXTENTS, then MINEXTENTS is set to the current number of extents. If the initial extent becomes smaller than INITIAL, then INITIAL is set to the value of the current initial extent. If you omit KEEP, all unused space is freed.
The allocate_extent_clause lets you explicitly allocate a new extent for the index. For a local index on a hash-partitioned table, Oracle allocates a new extent for each partition of the index.
Restriction: You cannot specify this clause for an index on a temporary table or for a range-partitioned or composite-partitioned index.
Specify the size of the extent in bytes. Use K or M to specify the extent size in kilobytes or megabytes. If you omit SIZE, Oracle determines the size based on the values of the index's storage parameters.
Specify one of the datafiles in the index's tablespace to contain the new extent. If you omit DATAFILE, Oracle chooses the datafile.
Use the INSTANCE clause to make the new extent available to the specified instance. An instance is identified by the value of its initialization parameter INSTANCE_NUMBER. If you omit this parameter, the extent is available to all instances. Use this parameter only if you are using Oracle with Real Application Clusters.
Explicitly allocating an extent with this clause does not change the values of the NEXT and PCTINCREASE storage parameters, so does not affect the size of the next extent to be allocated.
Use the PARALLEL clause to change the default degree of parallelism for queries and DML on the index.
Restriction: You cannot specify this clause for an index on a temporary table.
Specify NOPARALLEL for serial execution. This is the default.
Specify PARALLEL if you want Oracle to select a degree of parallelism equal to the number of CPUs available on all participating instances times the value of the PARALLEL_THREADS_PER_CPU initialization parameter.
Specification of integer indicates the degree of parallelism, which is the number of parallel threads used in the parallel operation. Each parallel thread may use one or two parallel execution servers. Normally Oracle calculates the optimum degree of parallelism, so it is not necessary for you to specify integer.
Use the physical_attributes_clause to change the values of parameters for a nonpartitioned index, all partitions and subpartitions of a partitioned index, a specified partition, or all subpartitions of a specified partition.
Restrictions:
PCTUSED parameter at all when altering an index.
PCTFREE parameter only as part of the rebuild_clause, the modify_index_default_attrs clause, or the split_partition_clause.
Use the storage_clause to change the storage parameters for a nonpartitioned index, index partition, or all partitions of a partitioned index, or default values of these parameters for a partitioned index.
Use LOGGING or NOLOGGING to specify whether subsequent Direct Loader (SQL*Loader) and direct-path INSERT operations against a nonpartitioned index, a range or hash index partition, or all partitions or subpartitions of a composite-partitioned index will be logged (LOGGING) or not logged (NOLOGGING) in the redo log file.
In NOLOGGING mode, data is modified with minimal logging (to mark new extents invalid and to record dictionary changes). When applied during media recovery, the extent invalidation records mark a range of blocks as logically corrupt, because the redo data is not logged. Therefore, if you cannot afford to lose this index, you must take a backup after the operation in NOLOGGING mode.
If the database is run in ARCHIVELOG mode, media recovery from a backup taken before an operation in LOGGING mode will re-create the index. However, media recovery from a backup taken before an operation in NOLOGGING mode will not re-create the index.
An index segment can have logging attributes different from those of the base table and different from those of other index segments for the same base table.
Restriction: You cannot specify this clause for an index on a temporary table.
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See Also:
Oracle9i Database Concepts and the Oracle9i Data Warehousing Guide for more information about |
These keywords are deprecated and have been replaced with LOGGING and NOLOGGING, respectively. Although RECOVERABLE and UNRECOVERABLE are supported for backward compatibility, Oracle Corporation strongly recommends that you use the LOGGING and NOLOGGING keywords.
RECOVERABLE is not a valid keyword for creating partitioned tables or LOB storage characteristics. UNRECOVERABLE is not a valid keyword for creating partitioned or index-organized tables. Also, it can be specified only with the AS subquery clause of CREATE INDEX.
Use the rebuild_clause to re-create an existing index or one of its partitions or subpartitions. If index is marked UNUSABLE, a successful rebuild will mark it USABLE. For a function-based index, this clause also enables the index. If the function on which the index is based does not exist, the rebuild statement will fail.
Restrictions:
INVALID. Instead, you must drop and then re-create it.
deallocate_unused_clause in this statement.
PCTFREE parameter for the index as a whole (ALTER INDEX) or for a partition (ALTER INDEX ... MODIFY PARTITION). You can specify PCTFREE in all other forms of the ALTER INDEX statement.
PARAMETERS clause (either for the index or for a partition of the index). No other rebuild clauses are valid.
ALTER INDEX ... REBUILD PARTITION).
Use the PARTITION clause to rebuild one partition of an index. You can also use this clause to move an index partition to another tablespace or to change a create-time physical attribute.
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Note: The storage of partitioned database entities in tablespaces of different block sizes is subject to several restrictions. Please refer to Oracle9i Database Administrator's Guide for a discussion of these restrictions. |
Restriction: You cannot specify this clause for a local index on a composite-partitioned table. Instead, use the REBUILD SUBPARTITION clause.
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See Also:
Oracle9i Database Administrator's Guide for more information about partition maintenance operations |
Use the SUBPARTITION clause to rebuild one subpartition of an index. You can also use this clause to move an index subpartition to another tablespace. If you do not specify TABLESPACE, the subpartition is rebuilt in the same tablespace.
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Note: The storage of partitioned database entities in tablespaces of different block sizes is subject to several restrictions. Please refer to Oracle9i Database Administrator's Guide for a discussion of these restrictions. |
Restrictions:
TABLESPACE and the parallel_clause.
Indicate whether the bytes of the index block are stored in reverse order:
REVERSE stores the bytes of the index block in reverse order and excludes the rowid when the index is rebuilt.
NOREVERSE stores the bytes of the index block without reversing the order when the index is rebuilt. Rebuilding a REVERSE index without the NOREVERSE keyword produces a rebuilt, reverse-keyed index.
Restrictions:
REVERSE or NOREVERSE for a partition or subpartition.
Specify the tablespace where the rebuilt index, index partition, or index subpartition will be stored. The default is the default tablespace where the index or partition resided before you rebuilt it.
Specify COMPRESS to enable key compression, which eliminates repeated occurrence of key column values. Use integer to specify the prefix length (number of prefix columns to compress).
Oracle compresses only nonpartitioned indexes that are nonunique or unique indexes of at least two columns.
Restriction: You cannot specify COMPRESS for a bitmap index.
Specify NOCOMPRESS to disable key compression. This is the default.
Specify ONLINE to allow DML operations on the table or partition during rebuilding of the index.
Restrictions:
ONLINE and then issue parallel DML statements, Oracle returns an error.
ONLINE for a bitmap index or a cluster index.
ONLINE when rebuilding an index that enforces a referential integrity constraint.
Specify COMPUTE STATISTICS if you want to collect statistics at relatively little cost during the rebuilding of an index. These statistics are stored in the data dictionary for ongoing use by the optimizer in choosing a plan of execution for SQL statements.
The types of statistics collected depend on the type of index you are rebuilding.
Additional methods of collecting statistics are available in PL/SQL packages and procedures
Specify whether the ALTER INDEX ... REBUILD operation will be logged.
The PARAMETERS clause applies only to domain indexes. This clause specifies the parameter string for altering or rebuilding a domain index or a partition of a domain index. If index is marked UNUSABLE, modifying the parameters alone does not make it USABLE. You must also rebuild the UNUSABLE index to make it usable.
The maximum length of the parameter string is 1000 characters. This string is passed uninterpreted to the appropriate indextype routine.
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Note: If you have installed Oracle Text, you can rebuild your Oracle Text domain indexes using parameters specific to that product. For more information on those parameters, please refer to Oracle Text Reference. |
Restrictions:
index is not marked IN_PROGRESS or FAILED, no index partitions are marked IN_PROGRESS, and the partition being modified is not marked FAILED.
index is not marked IN_PROGRESS.
index is not marked IN_PROGRESS or FAILED and partition is not marked IN_PROGRESS.
ENABLE applies only to a function-based index that has been disabled because a user-defined function used by the index was dropped or replaced. This clause enables such an index if these conditions are true:
DETERMINISTIC
Restriction: You cannot specify any other clauses of ALTER INDEX in the same statement with ENABLE.
DISABLE applies only to a function-based index. This clause enables you to disable the use of a function-based index. You might want to do so, for example, while working on the body of the function. Afterward you can either rebuild the index or specify another ALTER INDEX statement with the ENABLE keyword.
Specify UNUSABLE to mark the index or index partition(s) or index subpartition(s) UNUSABLE. An unusable index must be rebuilt, or dropped and re-created, before it can be used. While one partition is marked UNUSABLE, the other partitions of the index are still valid. You can execute statements that require the index if the statements do not access the unusable partition. You can also split or rename the unusable partition before rebuilding it.
Restriction: You cannot specify this clause for an index on a temporary table.
Specify RENAME TO to rename an index or a partition of an index. The new_index_name is a single identifier and does not include the schema name.
Restrictions:
index and any partitions of index must not be marked IN_PROGRESS or FAILED.
index must not be marked IN_PROGRESS or FAILED, none of the partitions can be marked IN_PROGRESS, and the partition you are renaming must not be marked FAILED.
Specify COALESCE to instruct Oracle to merge the contents of index blocks where possible to free blocks for reuse.
Restriction:
COALESCE clause of ALTER TABLE.
See Also:
COALESCE for information on coalescing space of an index-organized table
Use this clause to begin or end the collection of statistics on index usage. This clause is useful in determining whether an index is being used.
Specify MONITORING USAGE to begin statistics collection. Oracle first clears existing statistics on index and then begins to collect statistics on index usage. Statistics collection continues until a subsequent ALTER INDEX ... NOMONITORING USAGE statement is executed.
To terminate collection of statistics on index, specify NOMONITORING USAGE.
To see the statistics collected, query the ALL_, USER_, or DBA_INDEXES data dictionary views. To determine when the statistics collection began and ended, query the V$OBJECT_USAGE dynamic performance view.
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See Also:
Oracle9i Database Reference for information on the data dictionary and dynamic performance views |
The UPDATE BLOCK REFERENCES clause is valid only for normal and domain indexes on index-organized tables. Specify this clause to update all the stale "guess" data block addresses stored as part of the index row with the correct database address for the corresponding block identified by the primary key.
Restriction: You cannot combine this clause with any other clause of ALTER INDEX.
The partitioning clauses of the ALTER INDEX statement are valid only for partitioned indexes.
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Note: The storage of partitioned database entities in tablespaces of different block sizes is subject to several restrictions. Please refer to Oracle9i Database Administrator's Guide for a discussion of these restrictions. |
Restrictions:
ALTER INDEX statement (except RENAME and REBUILD), but you cannot combine partition operations with other partition operations or with operations on the base index.
Specify new values for the default attributes of a partitioned index.
Restriction: The only attribute you can specify for an index on a hash-partitioned or composite-partitioned table is TABLESPACE.
Specify the default tablespace for new partitions of an index or subpartitions of an index partition.
Specify the default logging attribute of a partitioned index or an index partition.
Use the FOR PARTITION clause to specify the default attributes for the subpartitions of a partition of a local index on a composite-partitioned table.
Restriction: You cannot specify FOR PARTITION for a list partition.
Use the modify_index_partition clause to modify the real physical attributes, logging attribute, or storage characteristics of index partition partition or its subpartitions.
The UPDATE BLOCK REFERENCES clause is valid only for normal indexes on index-organized tables. Use this clause to update all stale "guess" data block addresses stored in the secondary index partition.
Restrictions:
physical_attributes_clause for an index on a hash-partitioned table.
UPDATE BLOCK REFERENCES with any other clause in ALTER INDEX.
Use the rename_index_partition clauses to rename index partition or subpartition to new_name.
Restriction: You cannot rename the subpartition of a list partition.
Use the drop_index_partition clause to remove a partition and the data in it from a partitioned global index. When you drop a partition of a global index, Oracle marks the index's next partition UNUSABLE. You cannot drop the highest partition of a global index.
Use the split_index_partition clause to split a partition of a global partitioned index into two partitions, adding a new partition to the index.
Splitting a partition marked UNUSABLE results in two partitions, both marked UNUSABLE. You must rebuild the partitions before you can use them.
Splitting a usable partition results in two partitions populated with index data. Both new partitions are usable.
Specify the new noninclusive upper bound for split_partition_1. The value_list must evaluate to less than the presplit partition bound for partition_name_old and greater than the partition bound for the next lowest partition (if there is one).
Specify (optionally) the name and physical attributes of each of the two partitions resulting from the split.
Use the modify_index_subpartition clause to mark UNUSABLE or allocate or deallocate storage for a subpartition of a local index on a composite-partitioned table. All other attributes of such a subpartition are inherited from partition-level default attributes.
Restriction: You cannot modify the subpartition of a list partition.
The following statement alters the oe.cust_lname_ix index so that future data blocks within this index use 5 initial transaction entries and an incremental extent of 100 kilobytes:
ALTER INDEX oe.cust_lname_ix INITRANS 5 STORAGE (NEXT 100K);
If the oe.cust_lname_ix index were partitioned, this statement would also alter the default attributes of future partitions of the index. New partitions added in the future would then use 5 initial transaction entries and an incremental extent of 100K.
The following statement drops index partition ix_antarctica:
ALTER INDEX sales_area_ix DROP PARTITION ix_antarctica;
The following statement alters the default attributes of local partitioned index sales_ix3. New partitions added in the future will use 5 initial transaction entries and an incremental extent of 100K:
ALTER INDEX sales_ix3 MODIFY DEFAULT ATTRIBUTES INITRANS 5 STORAGE ( NEXT 100K );
The following statement marks the idx_acctno index as UNUSABLE:
ALTER INDEX idx_acctno UNUSABLE;
The following statement marks partition idx_feb96 of index idx_acctno as UNUSABLE:
ALTER INDEX idx_acctno MODIFY PARTITION idx_feb96 UNUSABLE;
The following statement changes the maximum number of extents for partition brix_ny and changes the logging attribute:
ALTER INDEX branch_ix MODIFY PARTITION brix_ny STORAGE( MAXEXTENTS 30 ) LOGGING;
The following statement sets the parallel attributes for index artist_ix so that scans on the index will not be parallelized:
ALTER INDEX artist_ix NOPARALLEL;
The following statement rebuilds partition p063 in index artist_ix. The rebuilding of the index partition will not be logged:
ALTER INDEX artist_ix REBUILD PARTITION p063 NOLOGGING;
The following statement renames an index:
ALTER INDEX emp_ix1 RENAME TO employee_ix1;
The following statement renames an index partition:
ALTER INDEX employee_ix1 RENAME PARTITION emp_ix1_p3 TO employee_ix1_p3;
The following statement splits partition partnum_ix_p6 in partitioned index partnum_ix into partnum_ix_p5 and partnum_ix_p6:
ALTER INDEX partnum_ix SPLIT PARTITION partnum_ix_p6 AT ( 5001 ) INTO ( PARTITION partnum_ix_p5 TABLESPACE ts017 LOGGING, PARTITION partnum_ix_p6 TABLESPACE ts004 );
The second partition retains the name of the old partition.
The following statement rebuilds index emp_ix so that the bytes of the index block are stored in reverse order:
ALTER INDEX emp_ix REBUILD REVERSE;
The following statement collects statistics on the nonpartitioned emp_indx index:
ALTER INDEX emp_indx REBUILD COMPUTE STATISTICS;
The type of statistics collected depends on the type of index you are rebuilding.
The following statement causes the index to be rebuilt from the existing index by using parallel execution processes to scan the old and to build the new index:
ALTER INDEX emp_idx REBUILD PARALLEL;
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