Description of problem:
When doing e.g. "dnf upgrade", instead of reading one line of every checksum_data file in there, it could use a database instead.

# find /var/lib/dnf/yumdb -type f -name checksum_data|wc -l
19196

Version-Release number of selected component (if applicable):
1.1.3-1

How reproducible:


Steps to Reproduce:
1.
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Actual results:
waste 10 minutes waiting (if no SSD) for dnf to read 19196 files

Expected results:
waste 0.1 seconds for a similar operation if using database

Additional info: