  Hardware acceleration of database query processing can be done with the help
of FPGAs. In particular, they are partially reconfigurable during runtime,
which allows for the runtime adaption of the hardware to a variety of queries.
Reconfiguration itself, however, takes some time. As the affected area of the
FPGA is not available for computations during the reconfiguration, avoiding
some of the reconfigurations can improve overall performance. This paper
presents optimizations based on query sequences, which reduces the impact of
the reconfigurations. Knowledge of coming queries is used to (I) speculatively
start reconfiguration already when a query is still running and (II) avoid
overwriting of reconfigurable regions that will be used again in subsequent
queries. We evaluate our optimizations with a calibrated model and measurements
for various parameter values. Improvements in execution time of up to 21% can
be obtained even with sequences of only two queries
