and periodically estimates operator selectivities. • The load shedder assigns a cost, ci, in cycles per tuple, and a selectivity, si, to each operator i. • The statistics manager collects metrics c=10 s=0.8 c=5 s=1.0 O1 c=10 s=0.9 L1=26.5 5 14 5 5 19 5 r1=10 r/s r2=20 r/s LT=640 cycles/s ??? Vasiliki Kalavri | Boston University 2020 Reacting to overload • Where in the query plan

vertex in V (no edges between vertices in the same part). A bipartite graph has no odd-length cycles (thus, no triangles). 39 Bipartite graph checking ??? Vasiliki Kalavri | Boston University 2020

operator must be available on a single host. • Avoid infinite recursion: caution if there exist cycles in the stream graph. Operator fusion A Avoid the overhead of serialization and transport B A