We approximate analytic queries on streaming data with a weighted reservoir sampling. For a stream of tuples of a Datawarehouse we show how to approximate some OLAP queries. For a stream of graph edges from a Social Network, we approximate the communities as the large connected components of the edges in the reservoir. We show that for a model of random graphs which follow a power law degree distribution, the community detection algorithm is a good approximation. Given two streams of graph edges from two Sources, we define the {\em Community Correlation} as the fraction of the nodes in communities in both streams. Although we do not store the edges of the streams, we can approximate the Community Correlation and define the {\em Integration of two streams}. We illustrate this approach with Twitter streams, associated with TV programs.