I worked for a small company where everything was open source. We used a Postgres database, etc. The tool was used for some minor reporting as it was hard to get the users of this small company to make a change.
Of all the open source tools we looked at Pentaho was the only one with a full suite of tools (i.e. ETL, reporting, dashboards, etc). A lot of the open source tools were either ETL (Talend) or reporting (Jaspersoft).