![]() ![]() Another major player is Microsoft SQL Server, but only for Windows platforms. Both are popular and support just about any type of database. Tier 1 represents the largest vendors having the most heavily implemented and supported products on the market. When choosing a DBMS, it is wise to select a product from a tier-1 vendor as listed in Table 2.1. When choosing a DBMS, select a product from a tier-1 vendor. So, exercise caution before deciding to choose a DBMS based solely on its ability to support a specific feature. Most of the major DBMS products have similar features, and if the feature or functionality does not exist today, it probably will within 18 to 24 months. Discourage deviation from the default unless a compelling business case exists-a business case that passes the technical inspection of the DBA group. For a shop with multiple operating systems and multiple types of hardware, choose a default DBMS for the platform. Whenever possible, the policy should minimize the number of different DBMS products. The DBA group should set a policy regarding the DBMS products to be supported within the organization. ![]() Business politics often work against the DBA group because it frequently possesses less organizational power than other business executives. This is a difficult provision to implement and even more difficult to enforce. No business unit should be allowed to purchase a DBMS without the permission of the DBA group. So what should be done? Well, the DBA group should be empowered to make the DBMS decisions for the organization. The DBA group should be empowered to make the DBMS decisions for the organization. The old DBMS remains and must continue to be supported. Furthermore, when a new DBMS is installed, old applications and databases are usually not migrated to it. Once a DBMS is installed, removal can be difficult because of incompatibilities among the different DBMSs and the necessity of converting application code. Then, when client/server computing became popular, additional DBMSs were implemented on UNIX, Linux, and Windows servers. For example, many mainframe shops moving from a hierarchic (IMS) or CODASYL (IDMS) database model to the relational model deployed DB2, resulting in an additional DBMS to learn and support. Sometimes the decision to buy a new DBMS is driven by the desire to support the latest and greatest technology. Perhaps the company purchased a commercial off-the-shelf application package that does not run on any of the current DBMS platforms. There are other reasons for the existence of multiple DBMS platforms in a single organization. Or, more likely, the DBAs know the application can be implemented using an existing DBMS but lack the organizational power or support to reject a new DBMS proposal. Sometimes a new DBMS product is purchased and installed without first examining if the application could be successfully implemented using an existing DBMS. Regardless of whether a DBMS exists on-site, a new DBMS is often viewed as a requirement for a new application. This is reasonable if your organization has no DBMS and must purchase one for the first time. ![]() Sometimes the decision to purchase and install a new DBMS is driven by a business need or a new application. Unfortunately, often the answer is that not much thought and planning went into the decision-making process. Who chose to install all these DBMSs and why? For example, it is not uncommon for a large company to use IMS or IDMS and DB2 on the mainframe, Oracle and MySQL on several different UNIX servers, Microsoft SQL Server on Windows servers, as well as pockets of other DBMS products such as Sybase, Ingres, Adabas, and PostgreSQL on various platforms, not to mention single-user PC DBMS products such as Microsoft Access, Paradox, and FileMaker. Yet, large and medium-size organizations typically run multiple DBMS products, from as few as two to as many as ten. The number of major DBMS vendors has dwindled due to industry consolidation and domination of the sector by a few very large players. The process of choosing a suitable DBMS for enterprise database management is not as difficult as it used to be. Choosing a suitable DBMS for enterprise database management is not as difficult as it used to be. ![]()
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