From the passage provided, extract the acquisition details of Tableau.
Tableau Software (/tæbˈloʊ/ tab-LOH) is an American interactive data visualization software company focused on business intelligence. It was founded in 2003 in Mountain View, California, and is currently headquartered in Seattle, Washington. In 2019 the company was acquired by Salesforce for $15.7 billion. At the time, this was the largest acquisition by Salesforce (a leader in the CRM field) since its foundation. It was later surpassed by Salesforce's acquisition of Slack.

The company's founders, Christian Chabot, Pat Hanrahan and Chris Stolte, were researchers at the Department of Computer Science at Stanford University. They specialized in visualization techniques for exploring and analyzing relational databases and data cubes, and started the company as a commercial outlet for research at Stanford from 1999 to 2002.

Tableau products query relational databases, online analytical processing cubes, cloud databases, and spreadsheets to generate graph-type data visualizations. The software can also extract, store, and retrieve data from an in-memory data engine.
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Tableau was acquired in 2019 by Salesforce for $15.7 billion.
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