Storage indexes build on the smart scan functionality by dividing the physical table data into storage regions and tracking the highest and lowest values for each storage region. When a SELECT query is run on the table, the smart scan code can compare the saved high and low values with the where clause from the […]
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Solving the performance problems in each of nine web application process steps requires different approaches, depending upon the location of the problem. Solving Client Machine Performance Problems (Steps 1 and 9) Performance degradations in the client machine are usually caused by page bloat burdening the client with rich UI components that could be eliminated. Determine […]
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Poorly written server-side code and a badly designed database will make any application run slower, but improving the performance of a slow running web application requires examination of the entire system, not just the database. A typical three-tier web application structure is shown in Figure 1. FIGURE 1. Web application process flow As shown in […]
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There are important tools found within the database realm that can be used to determine what is happening with the database. These tools are well documented, free, and reasonably easy to learn to use. Gaining familiarity with these tools is not only the responsibility of the DBA, but also database developers, user interface developers, application […]
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In the first article we considered the issue of managing small data volumes when working with Oracle LOBS and thinking about I/O tuning, and in the second, we considered buffer cache alternatives. If your database is running in ARCHIVELOG mode (as are the majority of databases), the problem of generating too many logs becomes a real headache […]
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In the previous article we considered the issue of managing small data volumes when working with Oracle LOBS and thinking about I/O tuning. Another critical performance question is how all operations with such large data volumes will impact the buffer cache. Oracle provides enough flexibility to adjust the caching option in a number of ways: […]
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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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