Execution Plan image:
TABLE ACCESS indicates a table access operation.
Execution Plan image:
Table Access operation.
Indexes can also be partitioned. While it is possible to create a partitioned index on an unpartitioned table, partitioned indexes will more often be created on a table that is itself partitioned.
When an index on a partitioned table is unpartitioned, or is partitioned on different column range conditions than the source table, the index is known as a Global Index.
Note: In general, Local (partitioned) Indexes help release the maximum benefits of partitioning. Avoid using Global Indexes on partitioned tables.
Execution Plan image:
Table Access operation.
TABLE ACCESS BY INDEX ROWID is used to access records using a ROWID obtained through an index lookup.
Execution Plan image:
Table Access operation.
Indexes can also be partitioned. To take advantage of partition maintenance facilities such as the ability to quickly drop a partition, you should normally create Local Indexes, which are partitioned in the same manner as their source table. When the leading columns of the index are also the columns upon which the index is partitioned then the index is known as a local prefixed index.
Local indexes have some significant advantages over global indexes. When a partitioned table with a global index has a partition split, merge, or move, the corresponding index partition will automatically have the same maintenance operation applied.
The parallel query option is invoked when the SQL statement includes a PARALLEL hint or when the PARALLEL clause has been associated with the table definition. In addition, the table to which the PARALLEL clause has been applied must be accessed by using a full table scan or must be a partitioned table accessed using a local index.
Note: In general, Local (partitioned) Indexes help release the maximum benefits of partitioning. Avoid Global Indexes on partitioned tables.
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