1Z0-515 Online Practice Questions and Answers

Correct Answer: A

Explanation:

Bitmap indexes are a highly compressed index type that tends to be used primarily for data warehouses.

Characteristic of Bitmap Indexes

*

For columns with very few unique values (low cardinality)

*

Columns that have low cardinality are good candidates (if the cardinality of a column is <= 0.1 % that the column is ideal candidate, consider also 0.2% 1%)

*

Tables that have no or little insert/update are good candidates (static data in warehouse)

*

Stream of bits: each bit relates to a column value in a single row of table

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Correct Answer: A

Explanation:

Partition-wise joins reduce query response time by minimizing the amount of data exchanged among

parallel execution servers when joins execute in parallel. This significantly reduces response time and

improves the use of both CPU and memory resources. In Oracle Real Application Clusters (RAC)

environments, partition-wise joins also avoid or at least limit the data traffic over the interconnect, which is

the key to achieving good scalability for massive join operations.

Partition-wise joins can be full or partial. Oracle decides which type of join to use.

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Correct Answer: A

Explanation: Oracle OLAP is a world class multidimensional analytic engine embedded in Oracle Database 11g. Oracle OLAP cubes deliver sophisticated calculations using simple SQL queries - producing results with speed of thought response times. This outstanding query performance may be leveraged transparently when deploying OLAP cubes as materialized views enhancing the performance of summary queries against detail relational tables. Because Oracle OLAP is embedded in Oracle Database 11g, it allows centralized management of data and business rules in a secure, scalable and enterprise-ready platform.

Correct Answer: A

Explanation: If your priority is manageability, use a local index. Local partitioned indexes are easier to manage than other types of partitioned indexes. They also offer greater availability and are common in DSS environments. The reason for this is equipartitioning: each partition of a local index is associated with exactly one partition of the table. This enables Oracle to automatically keep the index partitions in sync with the table partitions, and makes each table-index pair independent. Any actions that make one partition's data invalid or unavailable only affect a single partition.

Local partitioned indexes support more availability when there are partition or subpartition maintenance operations on the table. A type of index called a local nonprefixed index is very useful for historical databases. In this type of index, the partitioning is not on the left prefix of the index columns. References:

Correct Answer: B

Explanation: In a data warehouse, a dimension is a data element that categorizes each item in a data set into non-overlapping regions. A data warehouse dimension provides the means to "slice and dice" data in a data warehouse. Dimensions provide structured labeling information to otherwise unordered numeric measures. For example, "Customer", "Date", and "Product" are all dimensions that could be applied meaningfully to a sales receipt. A dimensional data element is similar to a categorical variable in statistics. The primary function of dimensions is threefold: to provide filtering, grouping and labeling. For example, in a data warehouse where each person is categorized as having a gender of male, female or unknown, a user of the data warehouse would then be able to filter or categorize each presentation or report by either filtering based on the gender dimension or displaying results broken out by the gender.

Correct Answer: D

Explanation:

Correct Answer: C

Explanation:

A Physical standby database replicates the exact contents of its primary database across the Oracle Net

network layer. While the physical storage locations can be different, the data in the database will be

exactly the same as the primary database.

Incorrect answer:

A, B: Logical standby databases convert the redo generated at the Primary database into data and SQL

and then re-apply those SQL transactions on the Logical standby, thus physical structures and

organization will be different from the Primary database. Users can read from logical standby databases

while the changes are being applied and, if the GUARD is set to STANDBY (ALTER DATABASE GUARD

STANDBY;), write to tables in the Logical standby database that are not being maintained by SQL Apply.

Unfortunately there are a number of unsupported objects (ie: tables or sequences owned by SYS, tables

that use table compression, tables that underlie a materialized view or Global temporary tables (GTTs))

and unsupported data types (ie: Datatypes BFILE, ROWID, and UROWID, user-defined TYPEs,

Multimedia data types like Oracle Spatial, ORDDICOM, and Oracle Text Collections (e.g. nested tables,

VARRAYs), SecureFile LOBs, OBJECT RELATIONAL XMLTypes and BINARY XML).[2] Physical standby

may be appropriate in such a case.

Correct Answer: D

Explanation:

Correct Answer: B

Explanation:

Correct Answer: B

Explanation:

ASM is a management tool, not a RAW performance tool.

Note:

Automatic Storage Management (ASM) is a new feature that has be introduced in Oracle 10g to simplify

the storage of Oracle datafiles, controlfiles and logfiles.

Automatic Storage Management (ASM) simplifies administration of Oracle related files by allowing the

administrator to reference disk groups rather than individual disks and files, which are managed by ASM.

The ASM functionality is an extention of the Oracle Managed Files (OMF) functionality that also includes

striping and mirroring to provide balanced and secure storage. The new ASM functionality can be used in

combination with existing raw and cooked file systems, along with OMF and manually managed files.

The ASM functionality is controlled by an ASM instance. This is not a full database instance, just the

memory structures and as such is very small and lightweight.

The main components of ASM are disk groups, each of which comprise of several physical disks that are

controlled as a single unit. The physical disks are known as ASM disks, while the files that reside on the

disks are known as ASM files. The locations and names for the files are controlled by ASM, but user-

friendly aliases and directory structures can be defined for ease of reference. The level of redundancy and

the granularity of the striping can be controlled using templates. Default templates are provided for each

file type stored by ASM, but additional templates can be defined as needed.

Failure groups are defined within a disk group to support the required level of redundancy. For two- way

mirroring you would expect a disk group to contain two failure groups so individual files are written to two

locations.

In summary ASM provides the following functionality:

*Manages groups of disks, called disk groups.

*Manages disk redundancy within a disk group.

*Provides near-optimal I/O balancing without any manual tuning. *Enables management of database

objects without specifying mount points and filenames.

*Supports large files.

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