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# Reader side of the native Delta round-trip test. Reads the Delta table
# (dimensions discovered from the transaction log) and the text reference,
# both genuine HDFS reads in a fresh process, and reports the elementwise
# reconstruction error together with the discovered dimensions.

Y    = read($1, format="delta")
Xref = read($2, format="text")

R = matrix(0, rows=1, cols=3)
R[1,1] = sum(abs(Xref - Y))   # 0 if ReaderDelta reconstructed the matrix exactly
R[1,2] = nrow(Y)              # discovered row count
R[1,3] = ncol(Y)              # discovered column count
write(R, $3)
