A warehouse fact table in your Oracle 12c Database is range-partitioned by month and accessed frequently
with queries that span multiple partitions
The table has a local prefixed, range partitioned index.
Some of these queries access very few rows in some partitions and all the rows in other partitions, but these
queries still perform a full scan for all accessed partitions.
This commonly occurs when the range of dates begins at the end of a month or ends close to the start of a
month.
You want an execution plan to be generated that uses indexed access when only a few rows are accessed
from a segment, while still allowing full scans for segments where many rows are returned.
Which three methods could transparently help to achieve this result?
A.
Using a partial local Index on the warehouse fact table month column with indexing disabled to the table
partitions that return most of their rows to the queries.
B.
Using a partial local Index on the warehouse fact table month column with indexing disabled for the table
partitions that return a few rows to the queries.
C.
Using a partitioned view that does a UNION ALL query on the partitions of the warehouse fact table, which
retains the existing local partitioned column.
D.
Converting the partitioned table to a partitioned view that does a UNION ALL query on the monthly tables,
which retains the existing local partitioned column.
E.
Using a partial global index on the warehouse fact table month column with indexing disabling for the table
partitions that return most of their rows to the queries.
F.
Using a partial global index on the warehouse fact table month column with indexing disabled for the table
partitions that return a few rows to the queries.
Explanation:
Note:
* Oracle 12c now provides the ability to index a subset of partitions and to exclude the others.
Local and global indexes can now be created on a subset of the partitions of a table. Partial Global indexes
provide more flexibility in index creation for partitioned tables. For example, index segments can be omitted for
the most recent partitions to ensure maximum data ingest rates without impacting the overall data model and
access for the partitioned object.
Partial Global Indexes save space and improve performance during loads and queries. This feature supports
global indexes that include or index a certain subset of table partitions or subpartitions, and exclude the others.
This operation is supported using a default table indexing property. When a table is created or altered, a default
indexing property can be specified for the table or its partitions.