Files revNNNN.dat

[Frodek]

I am read and analyze blkNNNNN.dat files but the are old:
Bitcoin-qt is downloading blocks...
blk00746.dat above half hours ago
and new files:
rev00743.dat
rev00746.dat
rev00744.dat
rev00745.dat
revNNNNN have the same format as  blkNNNNN? I wanna read up to latest coming block.

In rev can be forks and in blk not?

[achow101]

The blk.dat files contain the blocks as they are received over the wire and written to the disk. The rev.dat files contain undo data. From what I understand, that means that it is a place for Bitcoin Core to write down which blocks should be ignored in the blockchain because those blocks are stale. The place to find the latest incoming blocks would be the blk.dat files, however you should not be reading from those files directly, but rather using the various RPCs and notifiers supplied by Bitcoin Core.

[elbandi]

how can i purge this rev data for old blocks?

i think bitcoin will not undo 2014,2015,2016 year's blocks, so old rev files are unnecessary.

i can save disk space about 10-12GB.

[Casy]

Don't know about the rev files, but the downloaded blockchain size can be reduced using the "-prune" option of the client.