In Oracle, each operation with a LOB chunk requires physical I/O. As a result, you may end up with a high number of I/O-related wait events in the system. That is why proper management of I/O-related parameters is extremely important. The slightest mistake could have significant repercussions across the whole system. In this article, we […]
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When performance issues arise in a web application, you should first validate that the problem is actually in the database before you start to tune the server code. Starting from the outermost round trip, you should add timers to code that will run in the client and on the application server. However, you should be […]
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When PL/SQL functions are being called in multi-table joins, it is very important to keep in mind that you are operating on the merged sets. The following is a basic example: Note the outer join between EMP and DEPT. This causes the query to return 15 rows: 14 rows represent employees with associated departments; the […]
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Storage offload is a key performance optimization found only in Exadata. The Exadata storage server software understands Oracle database file layouts, so you can use smart scans to perform part of the work database servers normally do. By doing data processing closer to the storage, Exadata storage servers reduce the amount of data transferred to […]
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To understand Exadata’s performance, it’s helpful to look at traditional enterprise storage. Traditional storage is dominated by large storage area networks (SANs) and network attached storage (NAS) devices. These storage architectures help to share and manage storage among multiple client devices, but their main building blocks are large banks of rotating hard drives and solid-state […]
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Another type of engineered system is Oracle’s Exadata series of machines, which has been originally designed from the ground up to provide “extreme” performance and scalability for large data-warehousing, transaction-processing, and database consolidation workloads. This capability is delivered through a series of components, carefully chosen to integrate well together. Figure 1 shows the relationship between these components. […]
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One of the more powerful data analysis features introduced in Oracle Database 12c is SQL models. SQL models allow a user to create multidimensional arrays from query results. Formulas, both simple and complex, can then be applied to the arrays to generate results in which the user is interested. SQL models allow inter-row calculations to […]
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In this article, we discuss a feature of the Oracle Database that you can include in your arsenal: materialized views. Originally called snapshots, materialized views were introduced in Oracle8i and are only available in the Enterprise Edition. Like a regular view, the data in a materialized view results from a query. However, the results of a […]
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The different modes of setup for Oracle 12c Data Guard allow for different configurations that are adaptive and that are dependent on available hardware, processes, and ultimately business needs. The modes for the Data Guard configuration include maximum protection, maximum availability, and maximum performance. The Data Guard configuration can also have more than one standby […]
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Improving performance (and by this we usually mean query performance) is always a hot item with database administrators and users. One of the best and easiest ways to boost performance is to take advantage of the parallel processing option offered by Oracle Database 12c (Enterprise Edition only). Using normal (that is, serial) processing, the data involved […]
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As user communities require more and more detailed information to remain competitive, it has fallen to database designers and administrators to help ensure that the information is managed effectively and can be retrieved for analysis efficiently. In this section, we discuss partitioning data and the reasons why it is so important when working with large […]
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Migrating an Oracle instance from regular storage to ASM is actually a simple task, but only if the ASM instance has already been created. Using Oracle Enterprise Manager is probably the most straightforward way to do this. Start by opening up Oracle Enterprise Manager and choosing the option to migrate to ASM. The screen shown […]
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