There are many myths and incorrect information shared online about the SQL Server table variable, and it would be easy for a SQL Server developer to assume that, based on the misinformation, using a table variable instead of a temporary table was a good idea. Using table variable is in fact easy, but there are things a developer should […]
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Before we dig into the lesser known but important facts, I want to provide little background about the SQL Server Columnstore index. This feature was introduced in SQL Server 2012, but remains largely unknown. As the name suggests, a data page will store values only for the given column to which that page is allocated. Generally, […]
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When asked about common errors encountered in a SQL Server environment, you might expect to hear about high CPU issues, but in reality, these are rare and few. In fact, many DBAs report connectivity issues with SQL Server as among the most frequently encountered errors. These errors can further be classified into two sub-categories: Login request not reaching SQL Server. Login request reaching SQL […]
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Relations between countries, or between departments in a company, or between users and developers, are usually the product of particular historical circumstances, which may define current relations even though the circumstances have long since passed. The result of this can be abnormal relations, or, in current parlance, dysfunctional relations. History and circumstance often have the […]
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All of the Oracle databases, whether physical or logical, must be created as a physical standby first. The tools used to create the standby are RMAN, Data Guard Broker, or Oracle Grid Control. Steps must be completed on both primary and standby servers. However, the steps on the primary database need to be done only […]
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To improve the performance of an application, you can make local copies of remote tables that use distributed data or create summary tables based on GROUP BY operations. Oracle provides materialized views to store copies of data or aggregations. Materialized views can be used to replicate all or part of a single table or to […]
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The ORDER BY clause is executed after the WHERE, GROUP BY, and HAVING clauses. It can employ group functions, or columns from the GROUP BY, or a combination. If it uses a group function, that function operates on the groups and then the ORDER BY sorts the results of the function in order. If the […]
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Let’s take a moment to discuss the real power of a relational database. Once you’ve created a view with the count by category, and a second view displaying the count for the entire table, you can join them together to reveal information never before apparent. For instance, what percentage of the books are in each category? […]
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You can create a table that exists solely for your session or whose data persists for the duration of your transaction. You can use temporary tables to support specialized rollups or specific application-processing requirements whose results will not persist beyond the session or even past a COMMIT statement. To create a temporary table, use the […]
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Views can build on each other. You can easily join views to other views and tables to produce additional views to simplify the tasks of querying and reporting. As your groupings grow more complex, you will find that views are invaluable to your coding efforts; they simplify the representation of data at different grouping levels […]
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Scaling of existing software solutions is never a linear process. Contemporary database systems consume different kinds of resources (CPU time, memory, I/O channels) and behave differently when some of these resources become sparse. Considering that hardware is always limited by available budgets and technologies, it is critical to understand potential bottlenecks. Typically, this is accomplished […]
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The ASM instance can now be set up as a local ASM instance on the database server or as an ASM cluster. An ASM instance can manage the following files for all of the instances on each cluster node: control files, data files, tempfiles, spfiles, redo logs, archive logs, RMAN backups, Data Pump dumpsets, and […]
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