Activate/deactivate/verify PostgreSQL data checksums (Documentation)

 Data checksums allow the PostgreSQL database server to identify I/O failures
 when reading data from storage. The checksums stored in the page header of
 each data page are compared to the computed checksum of the read data.
 .
 Data checksums need to be activated at instance creation time, all current
 versions of PostgreSQL including v11 do not allow activating (or deactivating)
 checksums afterwards.
 .
 pg_checksums_ext can activate or deactivate data checksums as long at the
 database cluster is shutdown cleanly. Activating checksums requires all
 database blocks to be read and all page headers to be updated, so can take a
 long time on a large database. Deactivating checksums only requires the
 cluster control file to be updated so is quick.
 .
 In addition, pg_checksums_ext can verify the checksums in an online cluster.
 .
 This package contains the manpage.