  A compact group (CG) is a kind of special galaxy system where the galaxy
members are separated at the distances of the order of galaxy size. The strong
interaction between the galaxy members makes CGs ideal labs for studying the
environmental effects on galaxy evolution. The traditional photometric
selection algorithm biases against the CG candidates at low redshifts, while
the spectroscopic identification technique is affected by the spectroscopic
incompleteness of sample galaxies and typically biases against the high
redshift candidates. In this study, we combine these two methods and select CGs
in the main galaxy sample of the Sloan Digital Sky Survey, where we also have
taken the advantages of the complementary redshift measurements from the LAMOST
spectral and GAMA surveys. We have obtained the largest and most complete CG
samples to date. Our samples include 6,144 CGs and 8,022 CG candidates, which
are unique in the studies of the nature of the CGs and the evolution of the
galaxies inside.
