in reply to matching datetimestamps and concatenating data where timestamps match from multiple large datafiles
I assume that your files must be already sorted as they're log files, then what you are trying to do is a type of Merge Sort
You can then process you files one line at a time. Read the current line for fileA and decide if you want to write the current lines for fileB and fileC, and when you write a line from a file get the next one. Keep going until you run out of lines.
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