Self-service BI and data marts can lead to some quick wins for business units, but as data marts grow and the data changes, business users must spend increasing amounts of time managing them. Eventually, if the data grows big enough, the business users that once sought a way to bypass IT may need to go to IT for help, and dump a gnarly mess in IT's lap.
"Basically, we're asking our business users to become data engineers," Mariani explains. "That's less efficient; it's definitely not the best way of accomplishing the goal. The business units may have some early success with standing up new visualizations or dashboards, but when the data changes, they have to fill that role that IT has been filling historically, and they're not able to do it. They then have to call in IT to bail them out, and IT is not prepared or happy to bail them out."
Some organizations have tried to address this problem by embedding business users in IT, or deploying IT pros to individual business units, where they act as brokers between the lines of business and IT.
"That was the model we had at Yahoo," Mariani says. "Each business unit had their own IT and data teams. That's where we saw the proliferation of different tools, platforms, ways of storing the data. It was too costly and created an enormous amount of complexity."
In response, Mariani says, Yahoo's analytics team created a single data service that the business units could access via their BI tools.
"The single data service created tremendous value for the business as opposed to the distributed model," he says.
3. Data security suffers
With business units owning and managing their own data marts, the overall business loses control of the security of its data. The data tends to proliferate throughout the organization. Sensitive business data may end up sitting in spreadsheets and other BI tools on laptops and other devices, and it can become impossible for the organization to keep track of where copies of the data exist. Data origination and data lineage can become highly problematic.
"A loss of control of the data means also a loss of security," Mariani says. "You've got TDEs [Transparent Data Encryption files] sitting on laptops, core data assets are now being distributed through the organization with no way to secure it."
4. Self-service doesn’t scale
Self-service BI has arisen, in part, to achieve greater agility for lines of business. It has traditionally taken IT a long time to provide the data and insights that lines of business need to capitalize on business opportunities. Self-service BI offers the promise of giving business units access to the data and insights they need, when they need them. And in many ways, it has delivered on that promise. But as soon as you need to scale your BI efforts, the challenges become apparent.
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