From PostgreSQL wiki
When you visit our websites, our servers automatically log your IP address and/or host name.
We store information such as your email address, name and locality only if you decide to send us such information by completing a survey, or registering as a user on one of our sites. We collect this information to help us improve the content of our sites, customize the layout of our web pages and to contact people for technical and support purposes. We will not share your email address with other organizations unless required by law.
We may collect demographic and interest category information from people via surveys, volunteered information, suggestions from members, and other means. Our members may voluntarily provide information, including that regarding personal, interests, geography, and demographics. The purpose of this data collection is to ensure we continue to understand the needs and wants of the PostgreSQL community, and therefore can provide the most relevant information, guides, and content.