The attached patch makes an optimization to pg_checksums which prevents rewriting the block if the checksum is already what we expect. This can lead to much faster runs in cases where it is already set (e.g. enabled -> disabled -> enable, external helper process, interrupted runs, future parallel processes). There is also an effort to not sync the data directory if no changes were written. Finally, added a bit more output on how many files were actually changed, e.g.:
Checksum operation completed
Files scanned: 1236
Blocks scanned: 23283
Files modified: 38
Blocks modified: 19194
pg_checksums: syncing data directory
pg_checksums: updating control file
Checksums enabled in cluster
Cheers,
Greg
