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Data Warehousing Optimization which transforms Enterprises

Data warehousing is regarded as the dream of every business analyst. Here, all the information, relevant to the activities of a business is collected at a single place. It is considered to be the foundation of a successful Business intelligence program. Here is a list of few optimization techniques of Data Warehouse:

Use of Indexes in the Data Warehouses

Indexes play a vital role in the quick retrieval of data, which is present in the data warehouse. This section consists of different aspects of the use of indexes in the data warehouses. Bitmap indexes are used on an extensive scale in the environment, consisting of data warehousing. The Environment is known to consist of huge volume of data as well as ad hoc queries. It also comprises of a reduced level of concurrent DML transactions. For these applications, bitmap indexing offers lesser response time for the ad hoc queries of larger class. It also helps in the reduction of storage requirements, in comparison to different indexing processes. There may be a gain of dramatic performance on the hardware with a considerable amount of CPUs or the smaller amount of memory.

Bitmap indexes are meant for specific data warehousing applications in which the users make a query of the data, in place of updating it. It is not an ideal choice for OLTP applications where a wide array of concurrent transactions plays a vital role in modification of the data.

Parallel DML Work and Parallel query are known to work along with the bitmap indexes. In addition to this, bitmap indexing bestows support for the creation of concentrated indexes and indexes.

Bitmap Indexes and Cardinality

As bitmap indexes are used, they are beneficial for specific columns in which the ratio of the total count of unique values to the total count of rows, present in a certain table is small. It is also known to be the degree of the cardinality.

B-tree indexes are considered to be an efficient option for the high cardinality data. In the data warehouse solutions, the use of B-tree index is used for the specific columns, which involve high cardinalities. Most of the indexes, present in the data warehouse should be bitmap indexes. The bitmap indexes are useful in bringing an improvement in the query performance in the ad hoc queries as well as similar situations.

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Usage of bitmap join indexes in the data warehouse

In addition to the creation of bitmap index in the singular table, you can consider creating the bitmap join index. It is essentially a bitmap index to join more than two tables. A bitmap join index play a vital role in bringing an improvement in the performance by the magnitude order. By the storage of the results of the join, it is possible to avoid the join completely for the SQL statement with the aid of bitmap join index. In addition to this, it is known to have a smaller number of unique values for the bitmap join index in comparison to the regular bitmap index, present in the join column.

Usage of B-tree indexes

The B-tree index is considered to be organized in a similar way to the upside-down tree. You need to keep in mind that the bottom level of the index holds the real value of the data as well as pointers which are present in the corresponding rows.

It is recommended to make use of the B-tree indexes as the typical query indicates the indexed column and helps in the retrieval of specific rows. In similar queries, finding the row is really fast. B-tree indexes are used in the data warehouse on an extensive scale for enforcing the unique keys.

Usage of Index compression

The storage of Bitmap indexes is accomplished in the compressed and patented manner without the requirement of any kind of user intervention. A wide array of businesses firms go for storing these B-tree indexes in a compressed way as it saves an ample amount of space. Thus, it helps in the storage of more keys in each index block, which may lead to an effective performance.

Key compression enables the compression of B-tree index, that plays a vital role in the reduction of storage, present over the repeated values.

Global Indexes and local Indexes: Which one to select

B-tree indexes are primarily available on partitioned tables and they can be either global or local. Global indexes are not used in any data warehouse environment as the partition DDL statement will be validating the whole index. The rebuilding of index involves a huge cut off from the pocket. It is possible to maintain the global index without making the Oracle unusable after DDL, which is known to make global indexes really effective for specific data warehouse environment.

Also, local indexes are considered to be common, in comparison to global indexes. It is recommended to use global indexes in case a certain requirement cannot be met by the local indexes.

Usage of integrity constraints in the Data Warehouse

Integration constraints offer a mechanism for ensuring that the data is known to conform to the specific guidelines, which is specified by the data administrator. Few common kinds of constraints are inclusive of unique constraints which ensure that a specific column is unique. The NOT NULL constraints are effective in ensuring that none of the null values are allowed. Foreign key constraints are useful in ensuring that both the keys share a specific key for foreign key relationship.

It is possible to make use of constraints for several purposes in the data warehouse which includes data cleanliness as well as query optimization. Constraints are known to verify that the data, located in the data warehouse has a certain level of correctness and consistency. It is also useful in the prevention of the introduction of dirty data. The Oracle Database is known to make use of constraints during the optimization of SQL queries. Though constraints are considered to be useful in different aspects of the query optimization, they are used on an extensive scale for the query rewriting of different materialized views. If you’re making any drastic changes or improvements at your product or software, doesn’t it make sense to go with a company like Indium Software - Leading Data Warehouse Solution Provider.

Thanks and Regards,

Nikisha