aximum of 10K-50K times! With a 35M sample input file and 12K keys that I created for testing, I found this solution to be about <strong>200</strong> times faster.<pre class=language-awk data-lang=awk style=background-color:#f5f5f5;color:#1f1f1f;><code class=language-awk data-lang=awk><span style=color:#5597d6;>FNR</span><span style=color:#72ab00;>==</span><span style=color:#5597d6;>NR</span><span>{ </span><span style=color:#5597d6;>arr</span><span style=color:#72ab00;>[</span><span style=color:#5597d6;>$0<