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Data virtualization is an approach to data management that allows an application to retrieve and manipulate data without requiring technical details about the data, such as how it is formatted at source, or where it is physically located, [1] and can provide a single customer view (or single view of any other entity) of the overall data.
A schema crosswalk is a table that shows equivalent elements (or "fields") in more than one database schema.It maps the elements in one schema to the equivalent elements in another.
A common source of problems in ETL is a big number of dependencies among ETL jobs. For example, job "B" cannot start while job "A" is not finished. One can usually achieve better performance by visualizing all processes on a graph, and trying to reduce the graph making maximum use of parallelism , and making "chains" of consecutive processing ...
Tool Supported data models (conceptual, logical, physical) Supported notations Forward engineering Reverse engineering Model/database comparison and synchronization
A staging area, or landing zone, is an intermediate storage area used for data processing during the extract, transform and load (ETL) process. The data staging area sits between the data source(s) and the data target(s), which are often data warehouses, data marts, or other data repositories.
The most significant difference between ISQL and the previous Informix product was the separation of the database access code into an engine process (sqlexec), rather than embedding it directly in the client — thus setting the stage for client-server computing, with the database running on a separate machine from the user's machine.
Operational systems maintain a snapshot of the business, while warehouses maintain historic data through ETL processes that periodically migrate data from the operational systems to the warehouse. Online analytical processing (OLAP) is characterized by a low rate of transactions and complex queries that involve aggregations. Response time is an ...
A query language, also known as data query language or database query language (DQL), is a computer language used to make queries in databases and information systems. In database systems, query languages rely on strict theory to retrieve information. [1] A well known example is the Structured Query Language (SQL).