tempfile() uses a random hex to generate an unlikely existing file name

[dchiu911]

Instead of using tempdir() here, another robust alternative can be done using tempfile()

tempfile(pattern = "ocv-temp", fileext = ".sqlite")
#> [1] "/var/folders/7m/vs2l36sd0yl0d7p7mddnhc280000gp/T//Rtmp9hBCOI/ocv-temp67e27dca8d6f.sqlite"
tempfile(pattern = "ocv-temp", fileext = ".sqlite")
#> [1] "/var/folders/7m/vs2l36sd0yl0d7p7mddnhc280000gp/T//Rtmp9hBCOI/ocv-temp67e27d0bb2ed.sqlite"
tempfile(pattern = "ocv-temp", fileext = ".sqlite")
#> [1] "/var/folders/7m/vs2l36sd0yl0d7p7mddnhc280000gp/T//Rtmp9hBCOI/ocv-temp67e2b1025be.sqlite"

^{Created on 2021-12-21 by the reprex package (v2.0.1)}