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Good idea, the OP could blank out a thousand at a time as they needed to, that way preserving the more recent ones until they would probably not pertinent.Are years-old check numbers really important? I would say "not really". Date, payee, amount, and category are important.
You could simply erase old check number ranges. You'd lose the numbers, but avoid future duplicates. The Edit > Find & Replace function allows you to find all checks with numbers less than a specified number. You can't replace them with sensible numbers like 0001, 0002, etc., but you can easily wipe them all out.
I've used this approach because my bank limits me from100 to 999 and I have about 24 yrs of data.If I understand your issue correctly, I might have an easy solution. I ran into this a long time ago and when entering items in the register, I simply precede my actual check number with the two digits of the current year (i.e. 171001, 171002, 171003, etc.). Then, when I download to clear/reconcile, I manually match the item in my register. In 2018, I will switch to placing an 18 in front of check numbers. A little manual, but has worked well for me for multiple years.
To each his own, but no way would I recommend this option. Archiving is not a recommended way to go by most longtime Quicken user's.Another option would be do a "File>File Operations>Year-End-Copy" keeping only the most recent 2-3-4 or 5 years data in the current file. It keeps the historical data in a file and compacts file size of the current file.
Agree with Rhinecliff, my current data file dates back to 1996 and I would never delete any of it, history is too important and separating it into two or more files is throwing it away because there is no way to get a report of the combined data files from Quicken in the future.Another option would be do a "File>File Operations>Year-End-Copy" keeping only the most recent 2-3-4 or 5 years data in the current file. It keeps the historical data in a file and compacts file size of the current file.